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Microchip LoRa™ technology wireless module enables IoT: First module for ultra long-range and low-power network standard

Microchip announces the first in a series of modules for the LoRa™ technology low-data-rate wireless networking standard, which enables Internet of Things (IoT) and Machine-to-Machine (M2M) wireless communication with a range of more than 10 miles (suburban), a battery life of greater than 10 years, and the ability to connect millions of wireless sensor nodes to LoRa technology gateways. The 433/868 MHz RN2483 is a European R&TTE Directive Assessed Radio Module, accelerating development time while ... Read more Read more
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The Latest HMI Solutions from 1D to 3D

Just a few years ago Touch revolutionized input: mechanical buttons, keyboards and sliders were replaced by static plastic or metal surfaces. It meant that operator interfaces could be incorporated into a device, and unobtrusive and modern design became increasingly common on the factory floor. The technology - capacitive touch - is based on a capacitor whereby the human finger acts as the actuator for the capacitor. Ingenious designs also enable proximity switches to be implemented as well. In this case the control system is only active shortly before it is activated, thus reducing energy consumption. This is known as “1D” input.
Then, with the arrival of projective touch and resistive touch technology, the Multi-Touch was born. Here, users touch a touchscreen fitted in front of the monitor screen. Touch screen controllers calculate the touch point coordinates and transmit the data for processing. This is how “2D” input technology works.



Touchless control


Now there is “3D” input - gesture control “Our customers often ask for this,” reports Ileana Keges, Product Sales Manager for Microcontrollers at Rutronik Elektronische Bauelemente GmbH. “It has quite a few advantages over
standard touch technologies. Sensitive surfaces last longer, sterile surfaces remain sterile. Operators no longer need to wear gloves to operate machines from which oil or corrosive liquids might flow. Microchip has developed a solution for the purpose which we are pleased to recommend - the GesticIC MGC3130
.”

The near-field 3D tracking and motion controller is based on patented GestIC® technology from Microchip, which offers highly sensitive detection without blind spots and with a range of up to 15 cm. The input field is created from an electrode field, the e-field sensor, and the MGC3130 microcontroller analyses the signals.
The sensor panel consists of at least four electrodes, positioned at right angles to one another. They develop an electrical field of 3V and maximum 100kHz, which is spread evenly. If changes occur in the field, caused by hand movements, the sensor will detect these tiny signal changes. The MGC3130 processes the results in real time thanks to its 32 bit digital signal processor. The four electrodes can register movement in X, Y and Z directions. From these the MGC3130 calculates the hand movements. “It could be not only simple movements such as up and down, right and left, but also circular movements and symbolic gestures, a total of eight different gestures,” explained Ileana Keges. This enables the machine operator, for example, to open or close a valve by turning an imaginary button or to increase or decrease a fill level by making up and down movements.
The distance of maximum 15 cm ensures that only the intended motions are processed. “Since a conductive object needs to change the electrical fields in order for gesture recognition to take place using this technology, ‘false inputs’ caused by light or sound cannot occur”, explained Keges. Automatic self-calibration eliminates potential errors in the system and ensures consistent precision throughout the product's entire life.
Any solid, conductive materials can be used for the electrodes, for example boards, PCBs or conductive film. “That makes GestIC technology from Microchip a very cost-effective solution,” said Ileana Keges. Thin materials allow the solution to be integrated invisibly behind a housing without affecting the entire design of the device. The sensor can be installed behind non-conductive materials, e.g. 1 cm thick glass, plastic or ceramic. The area of the sensor is minimun 25 × 25 cm, maximum 140 × 140 cm. This means it can adjust to existing applications and an upgrade from 1D or 2D to 3D is easy to do. “These different technologies can also be combined if the electrodes are installed as a frame around a display that is also used as a touch interface. A practical application for this is a control panel with a display and buttons,” continued Ileana Keges.
Power uptake in active detection mode and continuous operation is just 150µW.
Moreover the MGC3130 is fitted with a few energy-saving features. The ‘approach detection’ facility provides a proximity switch. ‘Self-wake-up from sleep’ keeps the chip in self-wake up mode until the proximity sensor recognizes a movement by the user. Whereupon the system automatically switches into full sensor mode. If the user’s hand leaves the detection area, it switches back to energy-saving mode.
The sensor’s electrode design requires a certain amount of care, otherwise gestures will not be clearly recognized. To make developers’ work easier, Microchip supplies the Hillstar Development Kit as a reference,” explained Ileana Keges.
The Hillstar contains not only the GestIC® technology but also the Colibri Suite. The latter is used to set customer-specific parameters. This provides high-resolution X/Y/Z hand position tracking data such as stroke, circular and symbolic gestures at the digital output of the MCG3130.
At entry level Microchip offers a number of demo-kits, such as a light control system. In stand-alone mode the MGC3130 controls a bar of LEDs by hand movement.
The individual LEDs can be switched on and off in sequence. A circular hand movement controls light intensity. This is made possible with feature-rich ‘Aurea’ GUI software. Not only does this enable the MGC3130’s parameters to be set; it also simplifies the updating and saving process.

Customers to whom we have presented this system were very enthusiastic. Particularly for applications where machine operators wear gloves, whether during a medical intervention or on the factory floor, it is the ideal solution,” said Keges.

Optical solutions


Aside from the GestIC® technology from Microchip, Rutronik also offers gesture control systems by Vishay and Osram. “However it is not possible to compare them because they are based on an entirely different principle”, clarified Ileana Keges. Vishay and Osram opted for an optical solution. The proximity sensor / gesture control board by Vishay is based on the VCNL4020 proximity and ambient light sensor. With a radiance intensity of typically 80mW/sr at 200mA, it enables hand gestures to be detected up to 15cm above the sensor board. The movement is recognized by comparing the infrared signals on every transmitter. If the infrared light transmitted from an object, such as a hand, reflects, the VCNL4020 proximity sensor captures the reflection. To enable the signals from the different transmitters to be identified, they are multiplexed, i.e. they are cycled in rapid succession, one after the other. The proximity signal is output via the I2C interface between pulses. If a hand is located close to the board, it throws back a stronger signal from the transmitter above which it is situated. If the hand moves over and along the board, the signals from the other transmitters rise accordingly. This time difference in signal strength can now be analyzed in order to detect a movement and its direction.

GestIC® technology by Microchip is a unit consisting of a sensor surface and the MGC3130 Gestic IC. The maximum distance at which a gesture is recognized is 15cm.
In comparison, the optical version also requires a microcontroller to analyze the outgoing signals via the I2C interface.

An advantage of the optical solution is the larger distance (25cm) at which hand movements can be detected.

Since gestures are the most natural movement, 3D control will start to be used in even more ways, from applications inside domestic living spaces, and inside the car, to care and residential homes, hospitals and many more.”■

Rutronik
www.rutronik.com
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Creating designs that measure impact

Inspired by element14’s ‘Sudden Impact’ Wearable Design Challenge, this is the second in a series of exclusive blog posts for MDT that will explore the challenges of creating wearable medical devices.



Author: Christian DeFeo, eSupplier and Innovation Manager, Newark element14

The Sudden Impact challenge is in full swing and our participants are continuing to support a multitude of different sports through a number of innovative device designs. Head injuries and internal trauma remain two of the most widely discussed topics amongst researchers and medical personnel, but how can design engineers measure the ‘impact’ of these injuries? How can ‘impact’ be defined and what are its limits? These are just some of the questions that our participants will need to answer before they even start trying to make their designs a reality.

Our Sudden Impact finalists come from all corners of the world and as such, one of their key tasks has been to ensure their designs meet their countries’ respective standards in defining and measuring injuries.
Challengers are quickly realising that before they can bring their ideas to life, their designs must be in line with scientific and medical regulations that ensure that all relayed diagnostics are accurate and unchanging – the latter being extremely important for the trainers and athletes who will be relying on the data from these handmade devices.
In other words, our design engineers need to make sure their solutions cannot provide users with false injury information; this information could lead to potentially serious consequences, particularly if an existing injury is not detected accurately.

Head Injury Criterion: Footballers and Skiers


German-born Hendrik Lipka’s design is targeted at skiers and footballers and has two key functions: monitoring an athlete’s heart rate during training and acting as a helmet-mounted impact monitor during competitions. Hendrik’s research for the device focused on the biological and medical sciences, and this is where he discovered the ‘Head Injury Criterion’, or ‘HIC’ as it is more commonly known. HIC is used to detect the effect and duration of acceleration and deceleration at the moment of impact with the head, and has become a popular way to test the durability and security of sports equipment and safety gear.
The HIC formula uses an acceleration curve to calculate an average acceleration during a specific period of time – this is usually 15ms but can range from as little as 3ms, all the way up to 36ms. A maximum value is then calculated using the overall time frame, in order to determine the impact of the force of acceleration to the head. Interestingly, different variables can be substituted into the formula to make it applicable to other parts of the body too. An example of a real life situation where the HIC formula could be used is to detect the sharp drop in acceleration when a footballer collides with a team player on the pitch.
However, while the HIC formula seems like a perfect fit for his design, Hendrik has admitted some difficulties with the theory. Analog Devices’ ADXL series accelerometer only captures 800 or 1600 measurements per second, making his preferred accuracy much more difficult to obtain. Ideally these measurements would occur every millisecond to better calculate sum totals in a specific time frame through simple multiplication and division.

As such, Hendrik’s main challenge is in programming his helmet to calculate acceleration fast and efficiently enough, without compromising on battery life.

Cumulative concussions and contact sports


Kas Lewis from Canada is another one of element14’s Sudden Impact finalists and proposed the idea of a multi-sport helmet that can monitor for heat strokes, heart attacks and concussions. While many helmets were suggested throughout the challenge, Kas’ stood out because of its ability to measure repeat injuries to the head, or ‘cumulative concussions’.
Although single impact injuries are thought to have a long lasting effect on the brain, it is generally agreed that cumulative concussions are far more dangerous as they do not allow the brain enough time to recover from one impact, before another follows. As such, the helmet Kas has designed is best suited to contact sports such as football, where injuries are rife and can have significant long-term consequences for the player.

Kas’ design will incorporate a temperature sensor to detect abnormal body temperatures, as well as two separate accelerometers to monitor the severity of individual concussions with a high degree of accuracy. The device will also be fully equipped with monitoring and reporting capabilities, using the CC3100 in conjunction with the MSP430F5529 to collect and upload real-time information to a cloud-based system such as Plot.ly.
However, like Hendrik, Kas faces a number of challenges as it is ‘still not fully clear in the scientific community how [the impact of cumulative concussions] should be measured’. Medical professionals have acknowledged that research is still ongoing in to how these traumas should be diagnosed and monitored.
When dealing with traditional concussions, we are aware of the main symptoms - such as memory loss, headaches - and the tools that can aid diagnostic testing - such as MRIs and X-rays. But there is not as of yet a clear set of characteristics of a cumulative concussion, therefore Kas needs to carefully consider whether simply monitoring the injury is sufficient.

The need for flexible designs


Designing technologies to meet the medical and health sectors’ criteria for impact and injury is an ongoing discussion amongst professionals and has been for many years. The challenges that Hendrik and Kas face are real examples of how these discussions need to happen if we are to enable engineers to tackle real-life problems with new and innovative designs.
However, until a universal medical consensus on a condition is reached, engineers’ designs need to be flexible and fluid, anticipating changes to medical standards that are as of yet unconfirmed. This is one of the difficult challenges that our Sudden Impact finalists’ designs will need to address and, in the next blog post, we will be exploring just how much this compromise is affecting the functionality of their devices.
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Maxim Integrated Demonstrated Highly Integrated Analog Solutions at Embedded World 2015

Maxim Integrated Products, Inc. demonstrated highly integrated analog solutions for embedded applications at the Embedded World
2015 Exhibition and Conference in Nuremberg, Germany (February 24–26, 2015). Organized in three demo areas for Industrial Power, Industrial Interface, and Signal Chain, Maxim’s solutions showed systems engineers how to simplify designs and get to market faster.



Industrial Power


Step-down DC-DC converters eliminate external components and reduce total cost. A “demo in a box” features Maxim’s Himalaya series of highly efficient, 4.5V to 60V, synchronous DC-DC buck regulators from 25mA to 3.5A: MAX17552, MAX15062, and MAX17501 / MAX17502 / MAX17503 / MAX17504 / MAX17505.
Cooler, smaller, and simpler DC-DC step-down power modules reduce design complexity, manufacturing risks, and time to market. The Himalaya series pin-to-pin-compatible power modules, MAXM17503 / MAXM17504 / MAXM17505, integrate inductors, resistors, capacitors, and high-efficiency DC-DC step-down buck regulators. They operate over a 4.5V to 60V range. Customers can start with modules and migrate to ICs for volume production.

Industrial Interface


Symmetric key-based secure authenticator provides the most secure key storage possible. The MAX66242 DeepCover® SHA-256 secure authenticator configures and collects data from any embedded system through its NFC/RFID ISO/IEC 15693 and/or I²C (master/slave) interfaces.
Contactless communication secures sensitive data with the power of SHA-256 authentication. The MAX66300 is the industry's first HF RFID transceiver with integrated SHA-256 engine for secure challenge-and-response authentication.
Highly configurable IO-Link® transceiver ensures robust communications with IO-Link sensors and actuators. The MAX14826 IO-Link transceiver supports all specified IO-Link data rates, integrates multiple protection solutions, and is ideal for Industry 4.0 applications.

Signal Chain


Programmable analog offers more versatility for industrial control and automation, IoT, base-station RF controllers, and power-supply monitoring applications. The award-winning MAX11300 mixed-signal PIXI™ input/output (I/O) brings programmability to high-integration analog applications. It is the industry's first configurable, 20-channel, -10V to +10V high-voltage mixed-signal IC.
High 20-bit accuracy ensures confidence in measurement results. The MAX11905 is the fastest 20-bit, 1.6Msps successive approximation register (SAR) analog-to-digital converter (ADC). It saves up to 91% power and up to 50% space, with the best THD of -123dB at 10kHz.
Low-noise, low-distortion drivers optimize the high speed, high accuracy of SAR ADCs. The MAX44205/MAX44206 low-noise and low-power op amps drive high-speed SAR ADCs. Their wide supply range and wide bandwidth are ideal for low-power, high-performance data acquisition systems (DAS).
High resolution ADC is ideal for instrumentation applications that require ultra-low noise. The MAX11270 is an easy-to-use, 24-bit, 10mW, 64ksps delta-sigma ADC with integrated programmable gain amplifier (PGA); it offers the highest signal-to-noise ratio (SNR) and lowest power in its class.
Get high-resolution, 24-bit accuracy for weighing mass in a wide range of industrial applications. The MAXREFDES75#, a 24-bit weigh scale reference design, features the 24-bit MAX11270 delta-sigma ADC. The MAX11270 is ideal for process control, automatic test equipment (ATE), medical instrumentation, and battery-powered devices.
Ultra-robust, 5KVrms, 4-channel digital isolators transfer digital signals between circuits with different power and ground domains, where noise isolation, ground loop mitigation, and/or safety are of concern. Industry’s only 1.8V supply capable isolators, the MAX14930 /MAX14931/ MAX14932 / MAX14934 / MAX14935 / MAX14936 deliver best-in-class propagation delay of up to 30% better and pulse width distortion of up to 50% better than competitors.

Maxim Integrated
www.maximintegrated.com
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NEW PRODUCTS from Aurocon COMPEC

Aurocon Compec has a portfolio of over 500.000 products from over 2,500 trusted global brands and in every month it adds over 5.000 new products for the whole range. Choosing the right distributor is as important as choosing the right technical components for your business.
We offer you continuous improved services that can help you with your production facilities. An important part of our services refers to delivery. Now the lead time has become lower thus the delivery faster as in you can have now the products you need in 24 hours delivered directly to your door. No order is too small or less important for us!
You can find in the following a selection of new available products.


ELECTRONICS DESIGN ENGINEERS



Raspberry Pi 2 Model B
RS Stock No.: 832-6274

The Raspberry Pi 2 Model B represents a major performance increase over its single-core based predecessors: up to six times faster in fact. As well as a new quad-core Cortex-A7 processor, the Raspberry Pi 2 Model B now features 1GB of RAM memory. The operating system kernel has been upgraded to take full advantage of the latest ARM Cortex-A7 technology and is available with the new version 1.4 of NOOBS software (See Note below). Backward application hardware and software compatibility has been maintained with the Raspberry Pi 1 Model A+/B+.

Note: Previous versions of NOOBS software (1.3.x) are NOT compatible with Raspberry Pi 2 Model B. You may purchase a ready-programmed MicroSD memory card with NOOBS 1.4 software: 849-2012 or program your own after downloading NOOBS 1.4 from:
http://www.raspberrypi.org/downloads/
Few accessories: you can need for Raspberry Pi 2: approved power supply, RS Stock No: 822-6373, Raspberry Pi 2 Model B cases, RS Stock No: 819-3646, 819-3655 and 819-3658, Raspberry Pi 2 Model B is also available in boxes of 150, RS Stock No: 847-2816

Analog Devices: ADSP-BF707 Blackfin® Processor Evaluation EZ- Kit
RS Stock No.: 836-8733

Analog Devices offer the evaluation hardware Kit ADZS-BF707-EZLITE. This EZ KIT is for use with the BlackFin®ADSP-BF70x Digital Signal Processor series and it is supplied with an ICE-1000 emulator.
The Evaluation Board/Kit will provide a solution for evaluating the ADSP-BF70x Blackfin Digital Signal Processor (DSP) product family. The hardware is for use with the CrossCore® Embedded Studio (CCES) software and this development tool will test the ability of the ADSP-BF70x Blackfin Processors. It will support applications where you may need to debug and develop your design. The ADSP-BF707 Board Design Database contains all the necessary information for the design, layout, fabrication and assembly of the ADSP-BF707 EZ-Board.

ST Microelectronics: TSX634IPT
RS Stock No.: 829-1620

STMicroelectronics offer a range of Quad Operational Amplifiers (Op Amp). The amplifiers cover a span of types such as general purpose, enhanced, low power, low noise, high speed to CMOS versions. They can be operated in single or dual power supply that has several voltage ranges. The four Independent op amps are designed to suit Industrial control systems and automotive applications.
Ultra low current consumption makes ideal for designing into end devices such as power metering, electrochemical/gas sensors, medical instrumentation among others.

ELECTRONICS DESIGN ENGINEERS



Eaton: DE1 Variable Speed Starters
RS Stock No.: 820-3550

Offering precise control of AC motors with a simple initial setup, Fit & Forget design makes this starter perfect for less complicated installations.
For use in any manufacturing industry requiring speed control of AC motors
- Pre-wired as a motor starter for out of the box commissioning, no specialist drive knowledge required. Keeps installation errors to a minimum and saves cost
- Ideal for fan speed control, conveyor speed control, packaging machinery, centrifuges / mixers, automatic barriers.

RS Brand: Pressure Transducers and Transmitters
RS Stock No.: 828-5729

Pressure sensors for oil/water or alternatively for grey water. Offer a high-performance, value alternative to pressure sensors from more established brands, such as Druck or Gems. Ideal for flow control in Food and Beverage / Pharmaceutical / Paper Industry or Utilities.

Telemecanique: Preventa XY2CJ Grab Wire Switches and Rope Pull Kits
RS Stock No.: 837-1161

The Preventa XY2CJ emergency stop rope pull switches from Telemecanique are designed to prevent injury to people or damage to machinery when a normal emergency stop function is not available. They are easy to install and offer a quick visual check of the switch status for machine restart. Typical applications include woodworking machines, shears, conveyor systems, printing machines, textile machines, rolling mills, test laboratories, paint shops and surface treatment works.

MAINTENANCE AND INSTALLATION ENGINEERS



HellermannTyton: HEGWS Burst Protection Braided Sleeving
RS Stock No.: 829-9905

HEGWS range of sleeving can be used to protect hydraulic hoses, preventing injuries due to leaks emitting high pressure liquid jets. Also excellent tear resistance, abrasion protection, hydraulic hose optimum protection, liquid jet injuries minimised.
Meets EN ISO 3457 standard for Earth Moving Machinery and EN 1299 for Mechanical Vibration and Shock, making them ideal for protecting exposed pipework heavy-duty moving equipment (earth-moving), conveyors, large machinery.

Motorola T80 Two-Way Radio with LCD Display
RS Stock No.: 819-9127

Ultimate specification, rugged and all-weather proof, the TLKR T80Extreme is ready for adventures in the harshest of environments. A tough water resistant design and essential accessories, the TLKR T80Extreme will keep you in touch on the wildest tracks and highest peaks.

For more information about the products please access http://ro.rsdelivers.com

Aurocon Compec
www.compec.ro
www.designspark.com
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Power Modules Win Out, but Choose Wisely

Power modules are the way to go when it comes to leveraging the expertise of power experts and getting your design to market quickly, but choose wisely. Power-module architecture choices can greatly affect your power supply’s performance.



By Jian Yin, Intersil Corporation

Introduction


Whether evaluating step-down switching regulators at the silicon-level (controller with FET), or power modules where the integration, and ease of use of a more complete power supply subsystem may be preferred, system designers everywhere are under enormous pressure. They’re being tasked with integrating more power and features in ever-shrinking form factors, and thus adversely affecting the system’s electrical and thermal characteristics.
There are various obstacles system designers must overcome on the path to integration nirvana. These include the increased likelihood of noise coupling as components are in closer proximity, as well as heat dissipation, given that the power-handling capabilities continue to increase along with smaller footprint areas.
Fortunately, power module designers continue to innovate to meet these demanding requirements through various architectural and topological design approaches that extract the maximum performance from the smallest package. Yet, these innovations put the burden upon system designers in need of the optimum power module to be careful in their choice of solutions. The techniques used by different power module solutions can greatly affect overall system cost, as well as key performance parameters such as heat dissipation, transient response, ripple voltage, and even ease of use. It’s very much a case of ‘buyer beware’.

Figure 1:Highly integrated power modules require only input and output capacitors, and maybe a few additional external components to meet a system designer’s needs

The Case for Modular versus Discrete


For system designers, there are many reasons to opt for a power module versus designing a power converter from the component level, not least of which are ease of use and time-to-market. By adding only input and output capacitors, these power customers can finish their designs relatively easily and quickly, with confidence that their basic performance and space requirements have been met. The power module is a complete power converter system in an encapsulated package that includes a PWM controller, synchronous switching MOSFETs, inductors and passive components, see Figure 1.
For example, Intersil’s ISL8203M power module has an extremely low profile package at 1.83mm, which is similar to a 1206 capacitor’s height. Also, it delivers the excellent electrical and thermal performance to meet all customer requirements. Normally that knowledge would be sufficient, but how that module was designed can greatly affect more nuanced parameters, features and capabilities.

ISL8203M Deep Dive


ISL8203M is a complete DC-DC power module that has been optimized to generate low

Figure 2: The ISL8203M power-module package measures 6.5mm × 9mm × 1.85mm

Table 1: The ISL8203M is the industry’s most compact 6A encapsulated power module
output voltages ranging from 0.8V to 5V, making it ideal for any low-power, low-voltage applications. The supply voltage input range is from 2.85V to 6V. The two channels are 180° out-of-phase for input RMS current and EMI reductions. Each channel is capable of 3A output current. These channels can be combined to form a single 6A output in current-sharing mode. While in current-sharing mode, the interleaving of the two channels reduces input and output voltage ripple.
ISL8203M is only 1.83mm thick with a footprint of 6.5mm × 9mm, as shown in Figure

Figure 3: Efficiency of ISL8203M under various output voltage and current conditions a) One 3A output at 5Vin b). Paralleled 6A output at 5Vin
2. It has the most compact package profile for a given input and output voltage/current range, see Table 1, and its overall package volume is only 106mm3, which is dramatically smaller than all other power module solutions. Although the ISL8203M package is very compact, it is still delivers very good efficiency, as shown in Figure 3.

Small Module Package Offers Excellent Thermal Performance


The ISL8203M uses a QFN (quad-flat, no-leads) copper lead-frame package, where the internal component is soldered directly to the copper lead frame, see Figure 4.

Figure 4: ISL8203M internal structure

Figure 5: In a worst-case scenario, converting 5Vin to 3.3Vout at 6A -- with no air flow and an ambient temperature of 25°C -- the ISL8203M reached a maximum temperature of only 66.8°C
Also, the wire bonds can be applied to the top of the internal component for electrical connections to the lead-frame. Then the molding can be filled in to form a complete encapsulated package.
This structure allows the heat generated by the internal components to be dissipated directly by the copper in the lead frame which has a thermal conductivity of ~385 W/mK. This is about 1000 times the thermal conductivity of the printed circuit board (PCB) which has a typical thermal conductivity of ~0.343 W/mK.
As a result, the copper-based lead frame can help the heat dissipate much more efficiently than a PCB-based module.
Also, since the copper lead frame can be six times thicker than the 1oz copper on a typical PCB, the module lead frame can help spread the heat over a large area, thus accelerating the effective heat transfer area to the system board.
Overall, the module’s thermal performance can be better than a discrete solution where the component is soldered directly to the PCB system board.
It’s important to note that the molding material in the structure can have a similar heat-spreading effect to the copper lead frame. Although the molding material has a lower thermal conductivity, the heat can still transfer through the molding horizontally and then dissipate into the copper lead frame. The molding also increases the effective heat transfer area from the internal power component, and thus decreases the thermal resistance from the internal part to ambient. This is another important comparison benefit of power modules – the ability to handle high power in a small package versus discrete solutions.
Let’s take a closer look at the thermal performance of an ISL8203M mounted on a standard four-layer evaluation board with 2oz. copper on the top and bottom layers, and 1oz. copper in the middle layers, see Figure 5. Running a worst-case scenario of 5Vin to 3.3Vout/6A with no airflow and an ambient temperature of 25°C, the module’s maximum temperature is only 66.8°C.

For Transients, Current-Mode Power Module Achieves Better Performance


There are generally two types of control schemes used in module applications: current-mode and voltage-mode. To ensure a fast transient response under various load conditions, the ISL8203M uses a current-mode control scheme to regulate the output voltage, see Figure 6. The scheme’s current-sensing signal is derived from the voltage across the top FET’s conducting resistance (Rdson) of the synchronized buck converter. This is then fed into the current amplifier, the output of which undergoes slope compensation before being compared to the output error amplifier to generate what now becomes the pulse-width modulation (PWM) signal. Through the driver, the PWM signal can control the synchronized buck converter to achieve the required voltage regulation. The compensation on the error amplifier is needed to boost the loop gain and phase margin to achieve better performance and stability.

Figure 6: Current- and voltage-mode control diagram (a) ISL8203 Simplified current-mode control diagram (b) A typical voltage-mode control diagram
The structure of the voltage-mode control is simpler than current-mode control. It replaces the dashed block area in Figure 6 (a) with a saw-tooth ramp at a fixed frequency shown in (b). This saw-tooth ramp, instead of the current-mode design’s current-sensing signal, is then compared with the error amplifier’s output to generate the required PWM signal.
The voltage mode control is also easy to understand. As shown in the figure 7, its open-loop system is a two-order system, with the inductor and output cap forming the complex poles. Clearly, its normalized phase Tv(s), shown in Figure 7 (b) drops very fast by 180° across the 20kHz resonant frequency of the complex poles. This system depends upon the compensation components to improve the phase margin to achieve stability. Otherwise, it only has 10° phase margin with the crossover frequency at 50kHz, as shown in Figure 7 (b). Large phase margin (typically higher than 40°) is a necessity for the loop stability.

Figure 7: Open-loop Bode plots of voltage- and current-mode controls (a) Open-loop gain of voltage and current modes (b) Open-loop phase of voltage and current modes
If we use this same voltage-mode control system in (a) and modify it to the current loop shown in Figure 6 (a), it becomes a current-mode control system. The system open-loop Bode plot is shown in Figure 7 as Tc(s). This system is close to a single-order system at the low frequency range, so the phase is boosted dramatically from 20kHz to 500KHz, shown in Figure 7 (b).
Even without the compensation components, this is still a stable system. If a simple type II compensation is added to improve the low-frequency gain and push the crossover frequency to about 50KHz, the current-mode control phase margin can still be about 80°, which is sufficient for stability. So, for current-mode control, the compensation is relatively simple, versus voltage mode, and can cover a wide range of different output capacitors due to the large phase boost in open loop.
For power-module applications, the compensation is fixed inside the package, so if the output capacitors are changed with different customers’ applications, the complex poles in the voltage-mode control can be shifted significantly. The fixed compensation may not cover the wide range of output-capacitor changes since its open-loop phase is too low once over the LC resonant frequency. So in many cases, it can cause insufficient phase margins if the load conditions are changed. To avoid this, the voltage-mode module must lower the loop bandwidth (cross-over frequency) to ensure enough phase margin for stability at various load conditions compared to current-mode control. The penalty for lowering this bandwidth is poor transient response performance. To show this critical difference in transient performance, we selected one competitor’s 4A power module with voltage-mode control to compare with ISL8203M. The final loop Bode plots of these two power modules are shown in Figure 8.

Figure 8: Closed-loop Bode plots of current-mode and voltage-mode controls on module applications (5Vin to 1Vout/3A, with the same COUT=2×10µF ceramic + 47µF tantalum capacitor) (a) One 3A output of ISL8203M (b) A competitor’s voltage-mode module
If we select the same output capacitors for the test, with the phase margins both at ~60°, the ISL8203M loop bandwidth of one 3A output was much higher than the voltage-mode module, leading to the ISL8203M having much better transient performance, see Figure 9.

Figure 9: Output load transient response with the same output capacitors (5Vin to 1Vout 0 to 3A, COUT= 2×10µF ceramic + 47µF tantalum capacitor; load-current step slew rate at 1A/µs) (a) One 3A output of ISL8203M (b) A competitor’s voltage mode control power module
Under the same testing conditions, the ISL8203M has a peak-to-peak variation of 240mV and a recovery time of only 25µS, while the voltage-mode module has a peak-to-peak variation at 275mV and large recovery time of 70µS.

Paralleled Operation Provides Low Output Ripple


Finally, the ISL8203M can operate with dual 3A outputs or a single 6A output. When it runs at 6A, the two 3A outputs can be paralleled as shown in Figure 10. With the

Figure 10: ISL8203M can be quickly and easily programmed to parallel operation.
phase interleaving between two outputs at 180°, the input and output ripples can be reduced dramatically. As shown in Figure 11, the paralleled output ripple is only 11mV, while the competitor’s single-phase module ripple goes as high as 36mV, under the same test conditions.

Figure 11: Output ripple performance with the same output capacitors (5Vin to 1Vout 4A, COUT= 2×4.7µF ceramic + 68µF POSCAP capacitor; load-current step slew rate of 1A/µs) (a) ISL8203M ripple at 4A with two outputs in parallel (b) Ripple for a competitor’s 4A single-output module
More importantly, for a given output ripple, the ISL8203M needs less than half of the output capacitors compared to the single-phase module, thus providing significant cost savings.

Conclusion


The ISL8203M comes in a compact package yet still meets customers’ electrical and thermal performance requirements. The module’s standard evaluation requires no heat sink and no airflow, delivers a total power of 20W to the load, with the module reaching a maximum temperature of only 66.8°C.
Its current-mode control scheme allows the ISL8203M to achieve good transient performance with excellent peak-to-peak variation and a recovery time that is one-third that of competitive power modules. The ISL8203M’s special parallel mode also enables it to deliver 6A, with extremely low output ripple, and two outputs interleaved at 180°. This feature also comes with significant component cost savings for a given ripple limit. With all of these superior performance characteristics, the ISL8203M is a good candidate for any low-power, low-voltage application, such as test and measurement, communication infrastructure and industrial control systems, all requiring high density and good performance.
To meet the challenges of designing the power subsystem for these systems, many designers are using power modules instead of traditional discrete point-of-load designs, when time-to-market, size constraints, reliability and design capabilities are the motivating factors. Find out more about Intersil’s ISL203M power module at the web page: www.intersil.com/products/ISL8203M

About the Author:
Jian Yin is the Applications Engineering Manager for Industrial and Infrastructure Products at Intersil Corporation. He is responsible for analog and digital power module design and development, and all power module related customer applications support. Mr. Yin is the recipient of eight U.S. patents (including pending patents), and has published over 50 journal articles and technical papers. Prior to joining Intersil, Mr. Yin was a Senior Engineer at Monolithic Power Systems and a Module Design Engineer at Linear Technology Corporation, where he designed and released more than nine power module products. Mr. Yin holds a Ph.D. in Electrical Engineering from Virginia Polytechnic Institute and State University.

Intersil Corporation
www.intersil.com
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Light color control and management made easy

MAZeT GmbH presents their newest JENCOLOR® products for measurement tasks in the fields of color measurement and LED light.



The new products include the True Color sensor MTCSiCF for color and light measurement, the sensor signal amplifier MCDC04 with I²C interface as well as the sensor board MTCS-INT-AB4 and the Evaluation Kit MTCS-C3 (Colorimeter 3) for lighting applications. The JENCOLOR® sensors in combination with the signal ICs are an ideal match for applications with high requirement of temperature and long-term stability - such as LED lighting, color measurement tasks, industrial, medical or beauty applications as well as metrology.

True Color Sensor MTCSiCF



True Color Sensor IC MTCSiCF with CIE 1931 filter function in a QFN16
The JENCOLOR® MTCSiCF color sensor with space-saving QFN16 housing (4 x 4 x 0.9 mm) is the latest addition to the range of True Color sensors with XYZ filters. Thanks to their defined filter characteristics (standard spectral value function), these are ideal for ‘eye precise’ absolute color measurement, and can be used to accurately measure the colors of materials, liquids or light based on the CIE 1931/DIN 5033 industry standard. This makes measurement systems possible which can replicate human color perception and produce results which represent XYZ points in the LAB (LUV) color space. The sensor is suitable for all applications that require an optimum balance between price, size and colorimetric precision. Quality standards for color measurement and identification precision are always defined by the human eye.

Signal Conditioner MCDC04



Digital current-to-charge converter MCDC04
Input signal levels for light measurement need a wide dynamic range capable of covering several sizes. With its internal signal processing concept, the MCDC04 fulfills these requirements.
The programmable signal processing IC allows an input signal resolution up to 16 Bit and ensures a high degree of channel synchronization across the operating temperature range. The MCDC04 digital 4-channel current-to-charge signal converter is specially adapted to the requirements of the tristimulus JENCOLOR® color sensors.
The MTCSiCF color sensor combined with the MCDC04 is ideally suited to a variety of light measurement and control applications.

OEM Sensor Board MTCS-INT-AB4



The OEM sensor board MTCS-INT-AB4 with I2C interface for color measurements based on CIE 1931 and direct integration into controller-based measurement or control systems.
The sensor board MTCS-INT-AB4 is based on two new IC solutions, which are specially developed to solve tasks in LED lighting control - for example: feedback color control of LED light sources. The True Color sensors IC in implemented on the board performs color measurements based on the standard CIE 1931 - the human eye perception.
The signal converter MCDC04 is an analog-digital-converter (16 bit) with current-input, high dynamic range (1:1,000,000) and I2C output for direct implementation into controller-based systems. The board is an ideal OEM color sensor solution within the Luv/Lab color space with simple implementation based on the two modules on the board and an I2C interface. Therefore the OEM sensor is an ideal addition to all applications that require a high accuracy and stability of colors, even in harsh environmental conditions like temperature shifts. Examples are the calibration of cabin lights in airplanes, or the color management of backlights in displays or video walls.

OEM Sensor Board MTCS-C3



The OEM sensor board MTCS-C3 with USB interface for color measurement based on CIE 1931. Can be directly implemented into a customer-specific casing and used as USB colorimeter for test systems. Customer-specific pre-calibration can be performed by MAZeT.
The sensor board MTCS-C3 includes the same basic components as the MTCS-INT-AB4 and furthermore includes a micro controller and USB interface. This allows the sensor board to be used as OEM sensor unit, which can directly be implemented into customer-applications - as USB plug-and-play color sensor. Example applications are calibration of displays or backlight systems, or applications such as LED tests or common light measurement tasks.

MAZeT
www.mazet.de
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Opportunities for device differentiation

What is the Internet of Things?


The Internet of Things (IoT) is an emerging market trend impacting semiconductor devices, system OEMs, cloud service providers, and internet infrastructure companies. The trade press, accompanied by the types of companies mentioned above, has spilled a lot of ink on the subject, but this is typical in an emerging market with evolving requirements. For the purpose of this white paper, an IoT device or related service applies to the following characteristics.
• The device is connected via LAN, WLAN or WPAN.
• The device communicates certain localized information or requests for service to a network hub or through the network hub to a cloud-based service.
• The cloud accumulates data from the networked device or provides a service or capability to the networked device.

An IoT device can cover a great deal of capabilities and be part of a wide range of vertical markets. To break down the market segments of the Internet of Things, one can look at the requirements of the device in terms of:
• Sustained transmit and receive data rate required for the IoT device
• Type of data the IoT device is handling; for example, the IoT device can be generating or receiving video, audio or other content/data
• The level of processing at the edge of the network; for example, an accelerometer can measure acceleration and velocity, but local sensor data processing may convert that data into distance or energy
• The type of transactions between the device and the cloud; for example, whether the device provides any type of proprietary or sensitive data such as medical information which needs to be protected by HIPAA (Health Insurance Portability and Accountability Act of 1996) laws in the United States

Most IoT applications will be supported by wireless LANs – Wi-Fi (802.11n or 802.11ac) by 802.15.4 (Zigbee) and by Bluetooth.

Classes of IoT devices


IoT devices can be classified based on the type of data handled. It is useful to view the requirements for IoT devices in this way as a way of determining the device requirements from a power, connectivity and security perspective. We can classify the devices as follows based on the types of data handled:
• Machine to machine data
• Audio
• Audio/video

Table 1: IoT device classification
Table 1 shows the requirements of the IoT device based on the type of data handled. This table is for illustrative purposes and specific IoT device requirements may vary.

Figure 1: IoT continuum of capabilities

Table 2: Valid power states

Figure 2: Power management control for IoT

A continuum of capabilities


An IoT device connects a physical device to the cloud for services or further data processing. The device requires certain functional capabilities, and these capabilities will vary based on the application. There are a set of requirements that are needed by IoT devices, but the scope and the performance of those features will vary based on the application requirements. These feature set requirements are shown in Figure 1.

Power management


Power management is most important for mobile and other battery backed up devices. In a battery powered device, optimizing dynamic as well as static power is imperative. Power optimization is addressed in three different ways:
• Power management control
• IP implemented for low power
• Power aware software
• Power requirements and power management
• Processing power – both CPU and GPU
• Connectivity requirements
• Security requirements
• Cloud interface

Power management control should address the inclusion of voltage and frequency scaling. In order to integrate power management control into an IoT device, the system designer needs to identify the known power states for each of the major functional blocks within the device. Table 2 provides an example of power states that the blocks within an SoC that are valid.
IP blocks for IoT should be designed to include power control wrappers for power and frequency scaling as shown in Figure 2. IP providers, such as Imagination Technologies, can provide power control wrappers that will enable a functional IP block to be set to a valid power state within the device.
To implement IP for low power, the system designer must first identify the power management objectives. In the case of an IoT device, where the device is turned off for significantly longer time periods than it is turned on, leakage power will dominate the power consumption of the device. In the example of leakage power domination process selection, ie., where choosing a process technology with low leakage is an imperative, leaking can be further reduced by implementing the chip with high Vt devices and using power gating where ever possible.
If the device is turned on for the majority of time, as in IoT devices such as sensor hubs, dynamic power will dominate. To reduce the dynamic power, voltage and frequency scaling should be implemented as a part of the power management function. In addition, choosing processes and memory IP that can operate over low voltages, such as operating in the 0.7 V to 0.8 V regime in a 40nm process is highly desirable. A useful scheme to reduce power for a CPU is to close timing based on reduced values of supply voltage. This is commonly referred to as voltage scaling. For example, by operating a MIPS M-Class processor such as the M5150 CPU through voltage scaling at 0.95 V as opposed to the minimum voltage of 1.08 V results in a power reduction of 23%.
However, a lot of the dynamic power savings would be lost if the wireless communications systems operate inefficiently. Bluetooth Smart (also known as Bluetooth Low Energy or BTLE) is positioned for very low power wireless communications, but the power reduction comes at the cost of reduced range point-to-point communications, and low data rates. For applications requiring higher data rates (see Figure 1), Wi-Fi would be a suitable solution.
Imagination has developed a low power Wi-Fi offering including baseband called Ensigma ‘Whisper’. Low-power Wi-Fi is possible in Whisper by exploiting the low-power aspects within the 802.11 specification. Whisper can operate 802.11n over a single 2.4GHz band radio.

Security


A key requirement for IoT applications is security. IoT opens up networks to a variety of threats as more and more devices are connected to a network and eventually to the cloud. Figure 3 shows an example of an IoT device being used for home automation that is connected to a home network with possible threats to the network security.

Figure 3: Threats to networked devices

1) For more information, see the article on www.forbes.com/sites/leoking/2014/07/09/smart-home-these-connected-led-light-bulbs-could-leak-your-wi-fi-password/
2) For more information, see http://www.cryptography.com/public/pdf/DPA.pdf

At the edge of the network, as multiple IoT devices are added, the potential threats are greatly increased. The threats to networks with connected devices are documented and are newsworthy. The LifX brand of connected LED bulbs have been reported as being able to leak wireless security information.1)
IoT devices must be capable of providing a robustly secure environment. Security is achieved in the following ways:
• Secure boot
• Secure code update
• Key protection
• Tamper resistance
• Access control of secure resources
• Secure DMA (Direct Memory Access) with data encryption for critical functions
• Session authentication

Secure boot


When the IoT device is powered up and begins execution, the system must start execution with trusted code at boot time. In an IoT system, the trusted execution can be accomplished by having a secure CPU run trusted code on-chip. This trusted code must have its credentials secured from the time the credentials leave the secured credentialled vault to the time the code is implemented on the IoT device. The secure boot code must not be capable of being tampered. Imagination has developed and licenses IP that provides the secure boot feature required in IoT systems.

Figure 4: Benefi ts of virtualization

Secure code update


An IoT device can be hacked by corrupting the embedded software with malware. To protect against this type of attack requires the firmware to be properly credentialled and downloaded to the IoT device in a secure manner. The secure update, which is available as an intellectual property block from Imagination, is accomplished by means of including the hardware required on the IoT device to be encapsulated within a cryptographic boundary. The updated firmware is encrypted and downloaded to the IoT device where it is decrypted and the credentials are checked. This is an important use case in consumer devices where software updates are provided for bug fixes (including security improvements) as well as adding additional functional capabilities to the IoT device.

Key protection


Private keys consist of a set of addresses of OTP (One Time Programmable) memory which can be programmed with keys for encryption, authentication and device identifier. The memory needs to be configured on-chip so that:
• OTP is not accessible via external pins of the IoT SoC device
• OTP memory contents may be encrypted
• OTP memory contents are accessible only by ‘trusted processes’ running on the application processor

Tamper resistance


Simple Power Analysis (SPA), Differential Power Analysis 2) (DPA), and High Order Differential Power Analysis are techniques whereby analysis of the power and other electrical emissions from a semiconductor device can provide information about the encryption techniques and codes used. These emitted signals are a point of attack that require countermeasures. These attacks are addressed to the CPU and associated hardware that runs encryption and decryption. MIPS M-Class CPUs are tamper resistant by implementing the following countermeasures including user-defined scrambling of the cache memory address and data and injection of random pipeline stalls.

Table 3: Performance budgeting for a sensor hub application

Access control of secure resources


In an IoT system where a device is sending proprietary data or is engaged in commerce, the software processes running on the device are required to have secure access to peripherals and memory. This is needed to maintain security and to ensure malware cannot access the same information in memory or on peripherals as may be required by the secure processes. Consider the following example where a medical device may measure certain data on an individual, where such data is controlled by the HIPAA laws in the United States.
Also this example assumes that a second process is running that is communicating with a medical insurance company to validate insurance. In this case there may be multiple processes running on the CPU, but there are two processes running that are required to be secure and isolated. In this type of situation, virtualization is required in order to isolate the hardware resources committed to each of the secured processes running on the CPU, as illustrated in Figure 4. MIPS processors support hardware virtualization.

Secure DMA


DMA transfers to memory in a secure IoT device must be encrypted. The DMA engine and associated peripherals and memory should be encapsulated with in an encryption boundary so that any transfers into or out of the memory boundary will be encrypted or decrypted respectively.

CPU processing performance requirements


Architectural considerations for the CPU performance for an IoT device will depend on the scope of what the CPU needs to do, as well as hardware security provisions contained within the hardware of the CPU. For example, for an embedded controller IoT sensor hub system, the following performance requirements would be required.
In Table 3, a MIPS M5150 CPU, which includes hardware virtualization, is capable and provides 70 DMIPS/MHz to run the sensor interpretation code, the Wi-Fi stack, and internet communications with a clock speed of about 100 MHz. Most IoT devices will be designed with additional CPU capability to support additional features to be added via software upgrades. As a result, the performance of the CPU will need to be scalable, and may also include special pipeline stages to include special purpose processing that is deemed necessary in order to be done locally. The CPU chosen for a specific IoT application must not only support the security features as explained earlier, but must also be implemented in a way so that it is scalable in performance to support higher clock frequencies. For certain applications, it is also beneficial for the CPU to support hardware multi-threading, as in CPUs such as the MIPS I-Class processors.

Wireless communication


Typical wireless IoT devices will be enabled by specific standards. The standards deployed will depend on (1) the security requirements needed, (2) the type of network topology to be supported (eg., IP, mesh), and (3) the data rates to be supported. The diagram below provides a classification of IoT network requirements based on sustained data rates. Since Wi-Fi is pervasively deployed today, most IoT applications will support Wi-Fi.
Also, for LED lighting and applications that may span large geographic areas, ZigBee networks are used and may be present in IoT systems alongside Wi-Fi. Aside from HD video streaming applications such as those used in home entertainment or security video monitoring, 802.11n and 1x1 would provide sufficient bandwidth. The 802.11 networks will use dual band 2.4 GHz and 5.5 GHz frequencies.
For lower power and lower cost implementations, 802.11n can be supported by a single band 2.4 GHz radio. The lower frequency bands are more desirable since the RF transmission provides a greater range for a given power level output. By 2016, 802.11ah will become available for low data rate/low power IoT systems with Wi-Fi. This standard will be based on the 930 MHz frequency band.

Cloud interface


In an IoT system, the provision of services by the cloud will depend on several conditions. Security is a concern for device-to-cloud data transactions. An IoT device will need to support data encryption to the cloud via TLS or HTTPS. The software stack in the IoT device will need to support these security components.
In addition, cloud based communication can use more lightweight signalling such as COAP 3) (RFC-7252) and MQTT 4).

Figure 5: IoT applications vs. data rate requirements
Compared to HTTP, these lightweight signalling standards are desirable since they will (1) provide a reduced overhead for communicating to the cloud and (2) as the data communicated is reduced, data traffic on the internet will be reduced compared to using HTTP.
In addition, the different standards bodies have emerged to support IoT are aiming to develop software stacks that can be used across platforms.

Thread


The Thread Group ( www.threadgroup.org) has emerged in the development of a software stack that focuses on networks that are using 802.15.4 wireless mesh networks.
A key benefit of a mesh network is that if any device on the network fails, the network can continue to connect and communicate to other devices on the network.

Alljoyn


The Allseen Alliance ( www.allseenalliance.org) is a nonprofit consortium that is dedicated to driving the widespread adoption of products, systems and services that support the IoT with an open, universal development framework, initially based on the AllJoyn open source project.

Software requirements for IoT


Standards bodies, communications standards and security requirements all impact the elements that are needed for an IoT software stack contained in an IoT device SoC.
Cloud client software elements such as those supporting Imagination’s FlowCloud device-to-cloud technology, are added to the IoT device software stack. These elements support specific cloud communications requirements as may be required by the cloud service provider.
Figure 6 is an example of a software stack required to support an IoT device.

Figure 6: IoT software stack example

3) For more information, see http://coap.technology/
4) For more information, see http://mqtt.org/

Summary


As IoT devices become ubiquitous in networked systems, the SoC providers for these systems will differentiate their products based on security, power management, scalable computational performance and compliance to industry driven standards.
Wireless communications will become integrated into the main SoC not only to reduce cost, but also to reduce power consumption and improve system performance. The inclusion of wireless connectivity and its associated software stacks, integrated capabilities to do some local analytics, and security will increase the demand for computational power within the SoC device.
Security at the device and cloud level is required for IoT devices, especially those that are handling sensitive data such as medical data as these devices are communicating sensitive data to the cloud.
Power management is a significant issue for IoT devices that are mobile or are required to be powered by small batteries for an extended period of time. The IP used in such devices must be designed for low power and be easily integrated into SoC level power management schemes.
Imagination’s CPU, GPU, communications, video and imaging IPs are designed to meet the most aggressive requirements and opportunities for device differentiation in IoT applications ■

Imagination Technologies Limited
enquiries@imgtec.com
www.imgtec.com

UK t: +44 1923 260511
US t: +1 408 530 5000
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Wafer Level Chip Scale Package (WLCSP)

This document provides guidelines to use the Wafer Level Chip Scale Package (WLCSP) to ensure consistent Printed Circuit Board (PCB) assembly necessary to achieve high yield and reliability. However, variances in manufacturing equipment, processes, and circuit board design for a specific application may lead to a combination where other process parameters yield a superior performance. Guidelines for package performance information such as Moisture Sensitivity Level (MSL) rating, board level reliability, and thermal resistance data are included as reference.
This document contains generic information that encompasses Wafer Level Chip Scale Packages (WLCSP). It should be noted that device specific information is contained in Datasheet. This document serves only as a guideline to help develop a user specific solution. Actual experience and development efforts are still required to optimize the process per individual device requirements and practices.

Wafer Level Chip Scale Package (WLCSP)


Package Description
Wafer Level Chip Scale Package refers to the technology of packaging an integrated circuit at the wafer level, instead of the traditional process of assembling

Figure 1: WLCSP Packages Available from Freescale
individual units in packages after dicing them from a wafer. This process is an extension of the wafer Fab processes, where the device interconnects and protection are accomplished using the traditional fab processes and tools. In the final form, the device is a die with an array pattern of bumps or solder balls attached at an I/O pitch that is compatible with traditional circuit board assembly processes. WLCSP is a true chip-scale packaging (CSP) technology, since the resulting package is of the same size of the die (Figure 1). WLCSP technology differs from other ball-grid array (BGA) and laminate-based CSPs in that no bond wires or interposer connections are required. The key advantages of the WLCSP is the die to PCB inductance is minimized, reduced package size, and enhanced thermal conduction characteristics.

Typical WLCSP Configurations and Dimensions

Table 1: Die size for WLCSP Arrays at 0.40mm Pitch
Available WLCSP packages from Freescale range from 2.0 × 2.0 mm to 5.29 × 5.28 mm in size, with a standard pitch of 0.40mm and a standard solder ball diameter of 0.250mm. The physical outlines of WLCSP packages are dynamic since those depend on actual die size. Therefore, users of devices in these packages must exercise greater care in utilization than with more standardized packages. Refer to Table 1 for details regarding die sizes for standard solder ball arrays at 0.40mm pitch, which complies to JEDEC Publication 95, Design Guide 4.18 [1] and JEDEC Standard MO-211. [2]
The PCB layout and stencil designs are critical to ensure sufficient solder coverage between the package and the Printed Circuit Board (PCB). When designing the PCB layout, refer to the Freescale case outline drawing to obtain the package dimensions and tolerances.

WLCSP Construction

Figure 2: Typical Polymer-RDL WLCSP Construction
Refer to Figure 2 for a representation of a typical WLCSP package with a RDL layer between two dielectric layers. A WLCSP die has a first layer of dielectric, a Copper metal redistribution layer (RDL) to re-route the signal path from the die peripheral to a solder ball pad, and a second dielectric layer to cover the RDL metal, which in turn is patterned into the solder ball array. The solder ball is a lead-free alloy.

Process Flow
A typical WLCSP process flow is illustrated Figure 3. The illustration displays the process for a two-layer RDL process, with the RDL metal layer between two dielectric layers.

Figure 3: Typical WLCSP Process Flow

Printed Circuit Board (PCB) Level Guidelines


PCB Design Guideline

Table 2: Recommended PCB Pad and Stencil Parameters
PCB design requirements are based on IPC-A-600 [3] standards. For optimum electrical performance and highly reliable solder joints, Freescale recommends the PCB and stencil design guidelines listed in Table 2.

PCB Land Design Guidelines
Solder Mask Defined (SMD) pads are defined by the solder mask opening on the board pad as shown in Figure 4. The opening of the solder mask is smaller than the

Figure 4: NSMD and SMD Designs for WLCSP PCB Terminal
underlying copper area for soldering to the associated bump. A Non-Solder Mask Defined (NSMD) pad has a solder mask opening larger than the copper pad. There are many factors influencing whether the PCB designer uses SMD or NSMD pads. Either type can successfully be used with WLCSP packages. Freescale recommends using NSMD pads for thermal fatigue and SMD pads for drop test performance. Fillets where the trace connects to the Cu pad are recommended, especially with NSMD pads.

Via-In-Pad Structures
The need for via-in-pad structures will generally be determined by the design. Via-in-pad designs typically result in voids and inconsistent solder joints after reflow, leading to early failures. These voids are due to trapped air in the via. If via-in-pad structures must be used, it is recommended to use filled vias. As with any PCB, the quality and experience of the vendor is very important with via-in-pad designs.

Stencil Design Guideline
Due to the fine pitch and small terminal geometry used on WLCSP, particular attention must be paid to the paste printing process. In process inspection for paste height, percent pad coverage, and registration accuracy to solderable land patterns is highly recommended.

Solder Stencil Design and Fabrication
Stencils should be laser cut stainless steel with Nickel plating or electroformed Cobalt or Chromium hardened Nickel for repeatable solder paste deposition from ultra small apertures required by small pitch packages. It is recommended to inspect the stencil openings for burrs and other quality issues prior to use. Both square and round shaped apertures have been used successfully, however square shaped aperture openings provide more consistent paste printing and transfer efficiency when compared to round openings. Corners may be rounded to prevent clogging. 1:1 aperture to pad ratio is recommended for SnAgCu alloys.
For 0.40mm pitch WLCSP devices, use aperture aspect ratio of > = 0.66, with 0.25mm × 0.25mm square openings (25 micron corner radius) for improved solder paste deposition repeatability. Aperture aspect ratio is defined as the aperture opening area divided by the aperture side wall surface area.
A 0.100mm (4-mil) thick stainless steel stencil is recommended. When these stencil design requirements conflict with other required SMT components in a mixed technology PCB assembly, a step-down stencil process may be utilized in compliance with IPC-7525 [4] design standards.

PCB Assembly


Assembly Process Flow
A typical Surface Mount Technology (SMT) process flow is depicted in Figure 5.

Figure 5: SMT Process Flow

WLCSP PCB Assembly Guideline
Screen Printing: Solder Paste Material
Use of Type 4 (25 to 36 micron solder sphere particle size) or finer solder paste is recommended and a low halide (< 100ppm halides) No-Clean rosin/resin flux system be used to eliminate post-reflow assembly cleaning operations.

Component Placement
The WLCSP package is comparatively small in size. For better accuracy, it is recommended to use automated fine-pitch placement machines with vision alignment instead of chip-shooters to place the parts. Local fiducials are required on the board to support the vision systems.
Pick and Place systems using mechanical centering are not recommended due to the high potential for mechanical damage to the WLCSP device. Ensure minimal pick-and-place force is used to avoid damage, with all vertical compression forces controlled and monitored. Z-height control methods are recommended over force control. Freescale recommends the use of low-force nozzle options and compliant tip materials to further avoid any physical damage to the WLCSP device.
Use only vacuum pencil with compliant tip material whenever manual handling is required.
All assemblers of WLCSP components are encouraged to conduct placement accuracy studies to provide factual local knowledge about compensations needed for this package type. Freescale cannot anticipate the range of placement equipment and settings possible for package placement and therefore cannot make a generic recommendation on how to compensate for WLCSP interchangeability.

Reflow Soldering
Temperature profile is the most important control in reflow soldering and it must be fine tuned to establish a robust process. The actual profile depends on several factors, including complexity or products, oven type, solder type, temperature difference across the PCB, oven and thermocouple tolerances, etc. All of Freescale's WLCSP devices are qualified at Moisture Sensitivity Level 1 at 260°C. The maximum temperature at the component body should not exceed this level. Actual reflow temperature settings need to be determined by the end-user, based on thermal loading effects and on solder paste vendor recommendations.

Rework Procedure
WLCSP components removed during PCB rework should not be reused for final assemblies. Freescale follows standard component level qualifications for packages/components and these include three solder reflows survivability. A package that has been attached to a PCB and then removed has seen two solder reflows and if the PCB is double sided, the package has seen three solder reflows. Thus the package is at or near the end of the tested and qualified range of known survivability. These removed WLCSP components should be properly disposed of so that they will not mix in with known good WLCSP components.
The rework process for WLCSP devices is similar for typical BGA and CSP packages:

• To remove the faulty component from the board, hot air should be applied from the top and bottom heaters. An air nozzle of correct size should be used to conduct the heat to the WLCSP component such that the vacuum pick up tool can properly remove the component. It is recommended to apply top and bottom heaters simultaneously for 30 seconds at 300°C and 150°C, respectively. Many assembly sites have extensive in-house knowledge on rework and their experts should be consulted for further guidance.
• Once the WLCSP component is removed, the site is cleaned and dressed to prepare for the new component placement. A de-soldering station can be used for solder dressing. It should be noted that the applied temperature should not be > 245°C, otherwise the copper pad on the PCB may peel off.
• A mini-stencil with the same stencil thickness, aperture opening and pattern as the normal stencil should be used. Apply a gel or tacky flux using a mini-metal squeegee blade. The printed pads should be inspected to ensure even and sufficient solder paste before component placement.
• A vacuum nozzle is used to pick the new package up, and accurately place it using a vision alignment placement tool. A split light system that displays images of both the WLCSP leads and the footprint on the PCB is recommended.

The replaced component is then soldered to the PCB using a temperature profile similar to the normal reflow soldering process.

Moisture Sensitivity Level Rating


The Moisture Sensitivity Level (MSL) indicates the floor life of the component and its storage conditions after the original container has been opened. The lower the

Table 3: WLCSP MSL Capability
MSL value, the less care is needed to store the components. Table 3 depicts the best case MSL for each package size. All WLCSP devices at Freescale Semiconductor are MSL1, testing in accordance with IPC/JEDEC J-STD-020D. [5]
* Note: Please refer to Freescale Semiconductor web site for specific product MSL and package information, including JEDEC MSL.

Board Level Reliability


The board level reliability is usually presented in terms of solder joint life. The solder joint results in this section utilized the board layout guidelines from Section (PCB Design Guideline).


Figure 6: Example WLCSP / PCB Daisy Chain Routing (Not to Scale)
Testing Details
Samples of WLCSP in daisy chain format were used to study the solder joint reliability. BGA pairs were routed together in the WLCSP RDL layer, with a complementary pattern designed on the test PCB to provide one electrical circuit (net) through the package when the package is attached to the test PCB, as illustrated in Figure 6.

Solder Joint Reliability (SJR) Results
Assembled PCBs can be temperature cycled at a variety of temperature ranges. The most common test condition for small devices such as these at Freescale is JEDEC Condition 'G' [6] (-40°C/+125°C), with 15 minute dwell times for a typical frequency of one cycle per hour.
Freescale has the capability of continuously monitoring the resistance through a daisy chain package and its complementary test PCB. Failure is defined as resistance through the daisy chain net of 300 Ohms or greater. Daisy chain nets are tested (time zero testing) prior to temperature cycling.

Freescale continues to work on understanding and improving the solder joint reliability of WLCSP packages. From the various experiments, the solder joint reliability performances for the different package size, lead count, die thickness, and solder material are shown in Table 4. All experiments were performed using similar size test boards.

Table 4: WLCSP Solder Joint Reliability (-40°C / +125°C)

Table 5: WLCSP Solder Joint Reliability (0 / 100 °C)
An alternate condition (0/100 °C) was also evaluated. This condition employed 10 min ramp and dwell times, providing 1.5 cycles per hour. Results for this condition are shown in Table 5.

Underfill

Figure 7: Underfill Selection
Data on underfill was collected on a 5.29 × 5.28mm die size with SAC1205 0.25mm diameter solder spheres. Careful selection of underfill material is critical for enhancing BLR performance of WLCSP packages. Selecting an underfill with too high a CTE can result in worse BLR performance than no underfill. Underfilling can significantly increase the solder joint reliability of WLCSP packages. A comparison of non-underfill vs underfilled results for a 5.29 × 5.28mm die size shows a 7X improvement in cycles to 1st failure (201 vs 1421).

Mechanical Drop Test
WLCSP parts were tested per JEDEC's JESD22-B111 Drop Test Specification [7]. The drop test set-up, board layout, fixtures, and criteria are all based on the JESD22-B111. All drops are carried out in the -Z direction (package down). The peak acceleration is 1500g for 0.5 ms (half-sine pulse). The resistance at time zero and still state after the drop are recorded. Resistance data was collected in-situ throughout the dropping process, with maximum resistance data recorded during the drop. The failure criteria is 100 Ohms for 200 nano-seconds, recorded 3 times during 5 consecutive drops.

Table 6: WLCSP Drop Test Results
From the various experiments, the drop test performances for the different package sizes and lead counts are shown in Table 6.

Package Thermal Resistances


The thermal performance of WLCSP is characterized using two thermal board types and three boundary conditions:

Board Types:

1. Single Signal Layer - 1s (designed per JEDEC EIA / JESD51-3 [8].
2. Two Signal Layers, Two Internal Planes - 2s2p (designed per JEDEC EIA / JESD51-5 [9] and JEDEC EIA / JESD51-7 [10]

Thermal Resistance Boundary Conditions:
1. Junction-to Ambient (Theta-JA)
2. Junction-to-Board (Theta-JB)
3. Junction-to-Case (Theta-JC)

These thermal resistances help bound the thermal problem under distinct environments.

Junction-to Ambient (Theta-JA)
Junction-to-ambient thermal resistance (Theta-JA JEDEC EIA/JESD51-2 [11]) is a one-dimensional value that measures the conduction of heat from the junction (hottest temperature on die) to the environment near the package. The heat that is generated on the die surface reaches the immediate environment along two paths: (1) convection and radiation off the exposed surface of the package and (2) conduction into and through the test board followed by convection and radiation off the exposed board surfaces. Theta-JA is reported with two parameters, depending on the board type used: R JA and R JMA. R JA and R JMA help bound the thermal performance of the WLCSP package in a customer's application.

• R JA measures the thermal performance of the package on a low conductivity test board (single signal layer - 1s) in a natural convection environment. The 1s test board is designed per JEDEC EIA/JESD51-3 and JEDEC EIA/JESD51-5. R JA helps estimate the thermal performance of the WLCSP when it is mounted in two distinct configurations: (1) a board with no internal thermal planes (i.e., low conductivity board) or (2) when a multi-layer board is tightly populated with similar components.
• R JMA measures the thermal performance of the package on a board with two signal layers and two internal planes (2s2p). The 2s2p test board is designed per JEDEC EIA/JESD51-5 and JEDEC EIA/JESD51-7. R JMA provides the thermal performance of the package when there are no nearby components dissipating significant amounts of heat on a multi-layer board.

Junction-to-Board (Theta-JB)
Junction-to-board thermal resistance (Theta-JB or R JB per JEDEC EIA/JESD51-8 [12]) is also provided for the WLCSP. R JB measures the horizontal spreading of heat between the junction and the board. The board temperature is taken 1 mm from the package on a board trace located on the top surface of the board.

Junction-to-Case (Theta-JC)

Table 7: WLCSP Thermal Performance
Another thermal resistance that is provided is junction-to-case thermal resistance (Theta-JC or R JC). The case is defined at the exposed pad surface. R JC can be used to estimate the thermal performance of the WLCSP package when the board is adhered to a metal housing or heat sink and a complete thermal analysis is done.
Table 7 has some thermal information for certain WLCSP packages [13]. All of the data was generated using Silicon (Si) die. There is an inverse relationship between the body size of the package and the thermal resistances. Large packages have lower R JMA values. The greater the body size the more PTH vias will fit under the package ■

Notes:
1. Junction temperature is a function of die size, on-chip power dissipation, package thermal resistance, mounting site (board) temperature, ambient temperature, power dissipation of other components on the board, and board thermal resistance.
2. JEDEC EIA/JESD51-2 with the single layer board horizontal. Board conforms to JEDEC EIA/JESD51-3 and JEDEC EIA/JESD51-5.
3. Per JEDEC JESD51-6 [14] with the board horizontal. Board conforms to JEDEC EIA/JESD51-5 and JEDEC EIA/JESD51-7.
4. Thermal resistance between the die and the printed circuit board per JEDEC EIA/JESD51-8. Board temperature is measured on the top surface of the board near the package.

References
[1] JEDEC Publication 95, Design Guide 4.18, Wafer Level Ball Grid Arrays (WLBGA), Issue. A, September, 20004.
[2] JEDEC MO211, “Die Size Ball Grid Array, Fine Pitch, Thin/Very Thin/Extremely Thin Profile”, June 2004.
[3] ANSI/IPC-A-600G, “Acceptability of Printed Boards”, July 2004.
[4] IPC-7525, “Stencil Design Guidelines”, May 2007.
[5] IPC/JEDEC J-STD-020D.1, “Moisture/Reflow Sensitivity Classification for Nonhermetic Solid State Surface Mount Devices”, May 2008.
[6] JEDEC JESD-A104C, “Temperature Cycling”, May 2005.
[7] JEDEC JESD-B111, “Board Level Drop Test Method of Components For Handheld Electronic Products”, July 2003.
[8] EIA/JESD51-3, “Low Effective Thermal Conductivity Test Board for Leaded Surface Mount Packages,” August 1996.
[9] EIA/JESD51-5, “Extension of Thermal Test Board Standards for Packages with Direct Thermal Attachment Mechanisms,” February 1999.
[10] EIA/JESD51-7, “High Effective Thermal Conductivity Test Board for Leaded Surface Mount Packages,” February 1999.
[11] EIA/JESD51-2, “Integrated Circuits Thermal Test Method Environment Conditions - Natural Convection (Still Air)”, December 1995.
[12] EIA/JESD51-8, “Integrated Circuit Thermal Test Method Environmental Conditions - Junction-to-Board”, October 1999.
[13] V. Chiriac, “Wafer Level CSP Thermal Performance Evaluation”, Freescale Semiconductor, August 2008.
[14] EIA/JESD 51-6, “Integrated Circuits Thermal Test Method Environment Conditions - Forced Convection (Moving Air),” March 1999.

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