New 700-V HVICs Increases System Reliability, Shrink Board Space

Infineon Technologies recently launched a family of rugged, reliable 700-V High-Voltage ICs (HVICs) optimized for solar, power supply, uninterruptible power supplies (UPS), welding, and industrial drive applications. The 700-V offering enables designers of high-voltage power stages to simplify their designs while making them more robust.Infineon-700V-HVIC

The new IR7xxxS series of HVICs feature sink/source ratings from 60 to 2,300 mA and utilize PN junction technology. Available in half bridge and high- and low-side configurations, the new HVICs are optimized for 700-V MOSFETs and 650-V IGBTs and offer full driver capability with extremely fast switching speeds to reduce magnetics component count.

Other key features of the new devices include under-voltage lock-out protection for both channels, lower di/dt gate driver for better noise immunity. In addition, the HVICs are tolerant to negative transient voltage dv/dt, offer matched propagation delay for both channels and are 3.3- and 15-V input logic compatible.

The new IR7xxxS series is available in surface-mount (8-SOIC) packages in high volume. The lead-free devices are RoHS-compliant.

Source: Infineon

Power Monitoring IC for High-Accuracy Power Measurement

Microchip Technology recently expanded its power-monitoring IC portfolio with the addition of the MCP39F511. The highly integrated and accurate single-phase power-monitoring IC is designed for the real-time measurement of AC power. It combines the most popular power calculations with unique advanced features, making it well suited for use in high-performance commercial and industrial products (e.g., lighting systems, smart plugs, power meters, and AC/DC power supplies).

Source: Microchip Technology

Source: Microchip Technology

To address industry requirements for better accuracy across current loads, additional power calculations, and event monitoring of various power conditions, the MCP39F511 power-monitoring IC provides all of the popular standard power calculations combined with advanced features. The import and export of active energy accumulation, four-quadrant reactive energy accumulation, zero-crossing detection and dedicated PWM output have now been integrated on-chip, along with the ability to measure active, reactive and apparent power, RMS current and RMS voltage, line frequency, and power factor.

Allowing for more accurate power measurements, which is critical to higher-performance designs, this new device is capable of just 0.1 % error across a wide 4000:1 dynamic range. Additionally, its 512 bytes of EEPROM allow operating-condition storage. The MCP39F511 also includes two 24-bit delta-sigma ADCs with 94.5 dB of SINAD performance, a 16-bit calculation engine, and a flexible two-wire interface. A low-drift voltage reference, in addition to an internal oscillator, is integrated to reduce implementation costs. This unique combination of features and performance allows designers to add highly accurate power-monitoring functions to their end applications with minimal firmware development, speeding development time.

The MCP39F511 is supported by Microchip’s MCP39F511 Power Monitor Demonstration Board (ADM00667), which costs $150. The MCP39F511 is available now for sampling and volume production, in a 28-lead, 5 × 5 mm QFN package. It costs $1.82 each in 5,000-unit quantities.

Source: Microcchip Technology

Energy-Friendly IC and Evaluation Kit for iOS Accessory Development

Silicon Labs now offers a digital audio bridge chip and evaluation kit designed to simplify the development of accessories for iOS devices. Target applications include audio accessories such as guitar and microphone recording dongles, audio docks, and headphones. The CP2614 IC also provides built-in support for communication between iOS applications and accessory hardware, enabling a broad array of Internet of Things (IoT) accessories that operate with a companion iOS app.Silicon Labs CP2614

The CP2614 bridge chip and MFI-SL-CP2614-EK evaluation kit provide a cost-effective, comprehensive development platform for iOS accessory developers, enabling fast time to market through fixed-function MFi support. The CP2614 solution requires no firmware development, which helps developers get up and running quickly with their MFi accessory designs. Developers simply select their customization options with an easy-to-use GUI-based configuration tool.

The CP2614 bridge chip carefully manages and minimizes power consumption, achieving ultra-low power in both active and idle modes. The CP2614 IC’s energy efficiency makes it good choice for device-powered accessories. In addition, the CP2614 includes an integrated 5-V low drop-out (LDO) regulator, which reduces BOM cost and footprint for self-powered accessories. The CP2614 device operates without an external crystal or EEPROM, storing all configuration options on chip. The crystal-less architecture and integrated EEPROM further reduce BOM cost as well as PCB space, enabling developers to design smaller, more streamlined and cost-effective accessories.

 

The CP2614 audio bridge chip supports 24-bit unidirectional and 16-bit bidirectional digital audio streaming, enabling developers to create high-quality, high-performance “prosumer”-class audio accessories. The CP2614 can establish a communications channel with an iOS application, enabling the app to interact directly with the accessory hardware through general-purpose input/output (GPIO) read/writes and access to the UART for custom data flow. The GPIO can be configured for button input and LED output and accessed remotely from an iOS app or used to control audio playback.

 

The CP2614 audio bridge IC and MFI-SL-CP2614-EK evaluation kit are in full production and available to MFi licensees today. Available in a 5 mm x 5 mm QFN32 package, the CP2614 IC is priced at $2.51 (USD) in 10,000-unit quantities. The MFI-SL-CP2614-EK is priced at $59 (USD MSRP). MFi licensees can order the evaluation kit through the Apple MFi Procurement Portal.

Source: Silicon Labs

27-GHz Bandwidth Socket for Xilinx FLGA2577 BGA Package

Ironwood Electronics recently introduced a new high-performance BGA socket for 1-mm pitch, 2577 pin BGA ICs. The SG-BGA-6422 socket is designed for IC size 52.5 × 52.5 mm and operates at bandwidths up to 27 GHz with less than 1 dB of insertion loss. The sockets are designed to dissipate up to several watts without extra heat sinking and can handle up to 100 W with custom heat sink. The contact resistance is typically 20 mΩ per pin. The socket connects all pins with 27-GHz bandwidth on all connections. The socket is mounted on the target PCB with no soldering and uses industry’s smallest footprint. The socket is constructed with shoulder screw and swivel lid which incorporates a quick insertion method so that ICs can be changed out quickly. The socket comes with ball guide for the precise alignment of BGA balls to PCB pads.Ironwood C14363b

The SG-BGA-6422 socket is constructed with high performance and low inductance elastomer contactor. The temperature range is –35°C to 100°C. The pin self inductance is 0.15 nH and mutual inductance of 0.025 nH. Capacitance to ground is 0.01 pF. Current capacity is 2 A per pin. It works with ICs such as Xilinx BGA, 52.5-mm square package with 51 × 51 array and 1-mm pitch.

The SG-BGA-6422 is $1805, with reduced pricing available depending on the quantity required.

Source: Ironwood Electronics

H.264 Video I/O Companion Integrated Circuits

Microchip Technology has announced the availability of the OS85621 and OS85623, which are the world’s first H.264 video I/O companion integrated circuits (ICs) optimized for the Media Oriented Systems Transport (MOST) high-speed automotive infotainment and Advanced Driver Assistance Systems (ADAS) network technology. Microchip OS85621

Featuring a low-latency, high-quality H.264 codec and an on-chip Digital Transmission Content Protection (DTCP) coprocessor, the OS85621 enables automotive designers to quickly implement content-protected video transmission solutions. You can now transmit video streams with restricted access from devices (e.g., DIDs, digital media drives, and TV tuners) as encrypted H.264 over a MOST network.

The OS85621’s on-chip DTCP coprocessor accelerates the computation-intensive operations required for DTCP authentication and content protection. You can simultaneously route up to eight independent data streams through the DTCP coprocessor’s cipher engine for M6 or AES-128 encryption/decryption.

The ultra-low-latency mode of the H.264 codec enables single-digit millisecond latency from video input to video output, including encoding, transmission over a MOST network, and decoding. This real-time, high-speed video processing makes the OS85623—which has no DTCP coprocessor—an excellent option for camera-based ADAS applications that are designed to enhance vehicle safety.

The OS85621 and OS85623 H.264 video I/O companion ICs are now available in a BGA 196 package. Volume pricing starts at $8.

Source: Microchip Technology

Radiation-Hardened QDR-II+ SRAMs Achieve QML Class V Certification

Cypress Semiconductor Corp. recently announced its radiation-hardened (RadHard) 72-Mb Quad Data Rate II+ (QDR-II+) SRAMs and 4-Mb fast asynchronous SRAMs have achieved Qualified Manufacturers List Class V and Class Q requirements—the highest standards of quality and reliability for aerospace-grade ICs.CypressSRAM

The 72-Mbit QDR-II+ SRAMs deliver industry-leading throughput performance up to 36 Gbps by leveraging the ability to read and write data simultaneously. This throughput, combined with complete random access of data and free memory controllers for FPGAs, enables reconfigurable computing platforms that allow satellites to be reprogrammed while in space. The devices also feature the industry’s lowest latency and are ideal for radar and networking applications used in space

Both new SRAM families employ Cypress’s patented RadStop technology, which enables uncompromised functionality in the face of radiation up to 300 krads. The devices are manufactured in the Cypress’s fabrication facility in Bloomington, Minnesota, which is Microelectronics Trusted Category 1A accredited.

The radiation-hardened 4-Mbit devices deliver access times of 10 ns at 85°C and 12 ns at 125°C. They are also the first 90-nm, QML-V qualified devices of their kind and are ideal for a wide range of space and military applications.

Cypress’s RadStop technology combines manufacturing process hardening and proprietary design techniques. With RadStop technology, the SRAMs deliver single event latch-up immunity and single event functional interrupt immunity at temperatures as high as 125°C.

The Rad-Hard 72-Mb QDR-II+ SRAMs are available in a 165-column grid array (CGA) package. The devices come in the following four part numbers and configurations with equivalent Defense Supply Center Columbus (DSCC) part numbers:

  • CYRS1542AV18-250GCMB (x18 bus width, burst of 2); Class V part number: 5962F1120101VXA
  • CYRS1543AV18-250GCMB (x18 bus width, burst of 4); Class V part number: 5962F1120102VXA
  • CYRS1544AV18-250GCMB (x36 bus width, burst of 2); Class V part number: 5962F1120201VXA
  • CYRS1545AV18-250GCMB  (x36 bus width, burst of 4); Class V part number: 5962F1120202VXA

The CYRS1049DV33-12FZMB (5962F1123501VXA) 4-Mb fast asynchronous SRAMs are available in a 36-pin ceramic flat package.

Source: Cypress Semiconductor

GestIC Controller Enables One-step Design-in of 3-D Gesture Recognition

Microchip Technology recently announced a new addition to its patented GestIC family. The new MGC3030 3-D gesture controller features simplified user-interface options focused on gesture detection, enabling true one-step design-in of 3-D gesture recognition in consumer and embedded devices. Housed in an easy-to-manufacture SSOP28 package, the MGC3030 expands the use of 3-D gesture control features to high-volume, cost-sensitive applications such as audio, lighting, and toys.GestIC

The simplicity of gesture-detection integration offered by the MGC3030 is also achieved through Microchip’s free, downloadable AUREA graphical user interface (GUI) and easily configurable general-purpose IO ports that even allow for host MCU/processor-free usage. The MGC3030’s on-chip 32-bit digital signal processor executes real-time gesture processing, which eliminates the need for external cameras or controllers for host processing and allows for faster and more natural user interaction with devices.

The MGC3030 makes full use of the GestIC family development tools, such as Microchip’s Colibri Gesture Suite, which is an on-chip software library of gesture features. Intuitive and natural movements of the human hand are recognized, making the operation of a device functional, intuitive, and fun. Without the need to touch the device, features such as Flick Gestures, the Air Wheel, or the proximity detection perform commands such as changing audio tracks, adjusting volume control or backlighting, and many others. All gestures are processed on-chip, allowing manufacturers to realize powerful user interfaces with very low development effort.

Unique to GestIC technology, the programmable Auto Wake-Up On Approach feature begins operating in the range of 100-µW power consumption, enabling always-on gesture sensing in power-constrained applications. If real user interaction is detected, the system automatically switches into full sensing mode and alternates back to auto wake-up mode once the user leaves the sensing area. These combined features and capabilities provide designers with the ability to quickly integrate gesture detection features at price points that are ideal for high-volume devices.

Also available is Microchip’s Woodstar MGC3030 Development Kit (DM160226). The $139 kit is available via any Microchip sales representative, authorized worldwide distributor, or microchipDIRECT (www.microchip.com/Dev-Kit-012015a). The kit comes with the AUREA GUI, the central tool to parameterize the MGC3030 and the Colibri Suite to suit the needs of any design. AUREA is available via a free download at www.microchip.com/AUREA-GUI-012015a. The Colibri Gesture Suite is an extensive library of proven and natural 3-D gestures for hands and fingers that is preprogrammed into the MGC3030.

The MGC3030 featuring GestIC technology is available in a 28-pin SSOP package. Each unit costs under $2 each in high volumes.

Source: Microchip Technology

12-W Receiver IC for Wireless Mobile Device Charging

At CES 2015, Toshiba America Electronic Components introduced its newest IC enabling wireless mobile device charging. The TC7765WBG wireless power receiver controller IC can manage the 12-W power transfer required for the wireless charging of tablet devices. The TC7765WBG is compatible with the Qi low-power specification version 1.1 defined by the Wireless Power Consortium (WPC). It delivers a user experience comparable to that of conventional wired charging for tablets, as well as smartphones and other portable devices.Toshiba TC7765WBG

The TC7765WBG was built with Toshiba’s mixed-signal process using a high-performance MOSFET design that maximizes power efficiency and thermal performance. The IC combines modulation and control circuitry with a rectifier power pickup, I2C interface, and circuit protection functions. Compliance with the “Foreign Object Detection” (FOD) aspect of the Qi specification prevents heating of any metal objects in the path of wireless power transfer between the receiver and the transmitter.

The 12-W TC7765WBG is designed in a compact WCSP-28 2.4 mm × 3.67 mm × 0.5 mm package. This further facilitates design-in and contributes to the new chipset’s backward compatibility with the lower-power receiver IC. Combining the TC7765WBG with a copper coil, charging IC, and peripheral components creates a wireless power receiver. Joining the receiver with a Qi-compliant wireless power transmitter containing a Toshiba wireless power transmitter IC (e.g., TB6865AFG Enhanced version) forms a complete wireless power charging solution.

Toshiba announced that samples of the TC7765WBG wireless power receiver IC will be available at the end of January, with mass production set to begin in Q2 2015.

Small, Sixth-Generation Silicon TV Tuners

Silicon Labs recently launched the sixth generation of its high-performance TV tuner ICs. The Si2151 and Si2141 TV tuners are intended for the global hybrid TV and digital TV markets. Both support digital and analog video broadcasts, and they comply with all worldwide terrestrial/cable TV standards.SiliconLabs-TV-Tuner

  • The Si2151/41 tuners fully comply with the China GB/T 26686-2011 general specification for digital terrestrial television receivers.
  •  The Si2151/41 tuners deliver a large margin to this specification for the VHF-Low, VHF-High and UHF frequency bands.
  • At just 3 mm x 3 mm QFN, the Si2151/41 devices are the smallest TV tuner ICs available today.
  • The Si2151/41 devices require no balun on the RF input, and they integrate all tracking filter inductors, which dramatically reduces system cost and complexity.
  • The Si2151/41 tuners require no external power transistor for single-supply operation and eliminate the need for external inductive power supply filtering, resulting in the most cost-effective, highest performance on-board TV tuner designs
  • The Si2151/41 family shares a common API with Silicon Labs’ entire TV tuner portfolio.

Samples and production quantities of the Si2151/41 TV tuners are available now in a 3 mm x 3 mm 24-QFN package. The Si2151 worldwide hybrid TV tuner costs $0.72 in 10,000-unit quantities. The Si2141 worldwide digital TV tuner is priced at $0.70 in 10,000-unit quantities. Si2151-A-EVB and the Si2141-A-EVB evaluation boards are also available for $395.

Source: Silicon Labs

 

Long-Range, Memory Jewelry-Tagging Solution

EMThe EM4126 EPC radio-frequency identification (RFID) IC is designed to provide RFID tagging on small and/or high-value products (e.g., jewelry and watches). The IC’s high sensitivity enables long read ranges. EM4126-based tags can achieve –21-dBm read sensitivities. The ICs are designed for supply chain management, tracking and tracing, container identification, and access and asset control applications.

The EM4126’s 224 bits of nonvolatile memory support International Organization for Standardization (ISO) or Electronic Product Code (EPC) data structures and enable SGTIN-198 encoding, which uses alphanumeric serialization represented as a string of up to 20 7-bit characters. The EM4126’s additional features include ISO 18000-63 and EPC Class-1 Generation-2 compliance, 32-bit short-tag identification, 40-to-160 Kbps forward- and return-link data rates, and a –40°C-to-85°C extended temperature range.

Contact EM Microelectronic for pricing.

EM Microelectronic
www.emmicroelectronic.com

Battery Charger Design (EE Tip #130)

It’s easy to design a good, inexpensive charger. There is no justification for selling cheap, inadequate contraptions. Many companies (e.g., Linear Technology, Maxim, Semtech, and Texas Instruments) supply inexpensive battery management ICs. With a few external parts, you can build a perfect charger for just about any battery.

Texas Instruments’s UC2906 is an older (Unitrode) IC designed to build an excellent sealed lead-acid battery charger with a sophisticated charging profile. Figure 1 shows the recommended charger circuit.

Figure 1: This lead-acid battery charger uses Texas Instruments’s UC2906 IC.

Figure 1: This lead-acid battery charger uses Texas Instruments’s UC2906 IC.

In addition to the IC, only a handful of resistors and a PNP power transistor Q1 are needed to build it. Q1 must be rated for the maximum charging current and fitted with a heatsink.

An LED with its current-limiting resistor R can be connected to pin 7, which is an open-collector NPN transistor, to indicate the presence of power. Similarly, an LED with a series resistor could be connected to pin 9, which is also an open-collector NPN transistor to indicate overcharge (it is not used in Figure 1). The UC2906 datasheet and the Application Note provide tables and equations for selection of resistors Rs, Rt, RA, RB, RC, and RD and suggestions for adding various features.

Editor’s Note: This is an excerpt from an article written by George Novacek, “Battery Basics (Part 3): Battery Management ICs,” Circuit Cellar 280, 2013.

“No Opto” Synchronous Forward Controller

LinearThe LT3752/LT3752-1 is a high-input voltage-capable synchronous forward controller with an active clamp transformer reset. A controlled VOUT start-up and shut-down is maintained with an integrated housekeeping controller to bias the primary and secondary ICs. The internal bias generation also reduces the main power transformer’s complexity and size by avoiding the need for extra windings to create bias supplies.

The LT3752 operates over a 6.5-to-100-V input voltage range. The LT3752-1 is well suited for hybrid vehicle (HV) and hybrid electric vehicle (HEV) applications. For up to 400-V inputs and greater, it enables RC start-up from the input voltage with the maximum voltage limited only by the choice of external components.

A ±5% output voltage regulation can be attained without using an optocoupler. An optocoupler can be used to obtain ±1.5% output voltage regulation. The LT3752/-1 uses a pulse transformer to send a control signal to a secondary-side MOSFET driver for the synchronous rectification timing. It can also be used in self-driven applications the power transformer pulses control the secondary-side MOSFETs. With the LT3752/-1, secondary-side ICs no longer require start-up circuitry to operate when the output voltage is 0 V, which enables a controlled VOUT start-up.

The LT3752/-1 has a programmable 100-to-500-kHz operating switching frequency. It can be synchronized to an external clock, so a range of output inductor values and transformer sizes can be used.

The LT3752/-1 is available in a TSSOP-38 package with several pins removed for high-voltage spacing. The LT3752/-1 E- and I-grade versions function from a –40°C-to-125°C junction temperature. The LT3752/-1 H-grade functions from a –40°C-to-150°C operating junction temperature. The LT3752/-1 MP-grade functions from –55°C-to-150°C operating junction temperature.

The LT3752/LT3752-1 costs $3.39 in 1,000-piece quantities.

Linear Technology Corp.
www.linear.com

Q&A: Marilyn Wolf, Embedded Computing Expert

Marilyn Wolf has created embedded computing techniques, co-founded two companies, and received several Institute of Electrical and Electronics Engineers (IEEE) distinctions. She is currently teaching at Georgia Institute of Technology’s School of Electrical and Computer Engineering and researching smart-energy grids.—Nan Price, Associate Editor

NAN: Do you remember your first computer engineering project?

MARILYN: My dad is an inventor. One of his stories was about using copper sewer pipe as a drum memory. In elementary school, my friend and I tried to build a computer and bought a PCB fabrication kit from RadioShack. We carefully made the switch features using masking tape and etched the board. Then we tried to solder it and found that our patterning technology outpaced our soldering technology.

NAN: You have developed many embedded computing techniques—from hardware/software co-design algorithms and real-time scheduling algorithms to distributed smart cameras and code compression. Can you provide some information about these techniques?

Marilyn Wolf

Marilyn Wolf

MARILYN: I was inspired to work on co-design by my boss at Bell Labs, Al Dunlop. I was working on very-large-scale integration (VLSI) CAD at the time and he brought in someone who designed consumer telephones. Those designers didn’t care a bit about our fancy VLSI because it was too expensive. They wanted help designing software for microprocessors.

Microprocessors in the 1980s were pretty small, so I started on simple problems, such as partitioning a specification into software plus a hardware accelerator. Around the turn of the millennium, we started to see some very powerful processors (e.g., the Philips Trimedia). I decided to pick up on one of my earliest interests, photography, and look at smart cameras for real-time computer vision.

That work eventually led us to form Verificon, which developed smart camera systems. We closed the company because the market for surveillance systems is very competitive.
We have started a new company, SVT Analytics, to pursue customer analytics for retail using smart camera technologies. I also continued to look at methodologies and tools for bigger software systems, yet another interest I inherited from my dad.

NAN: Tell us a little more about SVT Analytics. What services does the company provide and how does it utilize smart-camera technology?

MARILYN: We started SVT Analytics to develop customer analytics for software. Our goal is to do for bricks-and-mortar retailers what web retailers can do to learn about their customers.

On the web, retailers can track the pages customers visit, how long they stay at a page, what page they visit next, and all sorts of other statistics. Retailers use that information to suggest other things to buy, for example.

Bricks-and-mortar stores know what sells but they don’t know why. Using computer vision, we can determine how long people stay in a particular area of the store, where they came from, where they go to, or whether employees are interacting with customers.

Our experience with embedded computer vision helps us develop algorithms that are accurate but also run on inexpensive platforms. Bad data leads to bad decisions, but these systems need to be inexpensive enough to be sprinkled all around the store so they can capture a lot of data.

NAN: Can you provide a more detailed overview of the impact of IC technology on surveillance in recent years? What do you see as the most active areas for research and advancements in this field?

MARILYN: Moore’s law has advanced to the point that we can provide a huge amount of computational power on a single chip. We explored two different architectures: an FPGA accelerator with a CPU and a programmable video processor.

We were able to provide highly accurate computer vision on inexpensive platforms, about $500 per channel. Even so, we had to design our algorithms very carefully to make the best use of the compute horsepower available to us.

Computer vision can soak up as much computation as you can throw at it. Over the years, we have developed some secret sauce for reducing computational cost while maintaining sufficient accuracy.

NAN: You wrote several books, including Computers as Components: Principles of Embedded Computing System Design and Embedded Software Design and Programming of Multiprocessor System-on-Chip: Simulink and System C Case Studies. What can readers expect to gain from reading your books?

MARILYN: Computers as Components is an undergraduate text. I tried to hit the fundamentals (e.g., real-time scheduling theory, software performance analysis, and low-power computing) but wrap around real-world examples and systems.

Embedded Software Design is a research monograph that primarily came out of Katalin Popovici’s work in Ahmed Jerraya’s group. Ahmed is an old friend and collaborator.

NAN: When did you transition from engineering to teaching? What prompted this change?

MARILYN: Actually, being a professor and teaching in a classroom have surprisingly little to do with each other. I spend a lot of time funding research, writing proposals, and dealing with students.

I spent five years at Bell Labs before moving to Princeton, NJ. I thought moving to a new environment would challenge me, which is always good. And although we were very well supported at Bell Labs, ultimately we had only one customer for our ideas. At a university, you can shop around to find someone interested in what you want to do.

NAN: How long have you been at Georgia Institute of Technology’s School of Electrical and Computer Engineering? What courses do you currently teach and what do you enjoy most about instructing?

MARILYN: I recently designed a new course, Physics of Computing, which is a very different take on an introduction to computer engineering. Instead of directly focusing on logic design and computer organization, we discuss the physical basis of delay and energy consumption.

You can talk about an amazingly large number of problems involving just inverters and RC circuits. We relate these basic physical phenomena to systems. For example, we figure out why dynamic RAM (DRAM) gets bigger but not faster, then see how that has driven computer architecture as DRAM has hit the memory wall.

NAN: As an engineering professor, you have some insight into what excites future engineers. With respect to electrical engineering and embedded design/programming, what are some “hot topics” your students are currently attracted to?

MARILYN: Embedded software—real-time, low-power—is everywhere. The more general term today is “cyber-physical systems,” which are systems that interact with the physical world. I am moving slowly into control-oriented software from signal/image processing. Closing the loop in a control system makes things very interesting.

My Georgia Tech colleague Eric Feron and I have a small project on jet engine control. His engine test room has a 6” thick blast window. You don’t get much more exciting than that.

NAN: That does sound exciting. Tell us more about the project and what you are exploring with it in terms of embedded software and closed-loop control systems.

MARILYN: Jet engine designers are under the same pressures now that have faced car engine designers for years: better fuel efficiency, lower emissions, lower maintenance cost, and lower noise. In the car world, CPU-based engine controllers were the critical factor that enabled car manufacturers to simultaneously improve fuel efficiency and reduce emissions.

Jet engines need to incorporate more sensors and more computers to use those sensors to crunch the data in real time and figure out how to control the engine. Jet engine designers are also looking at more complex engine designs with more flaps and controls to make the best use of that sensor data.

One challenge of jet engines is the high temperatures. Jet engines are so hot that some parts of the engine would melt without careful design. We need to provide more computational power while living with the restrictions of high-temperature electronics.

NAN: Your research interests include embedded computing, smart devices, VLSI systems, and biochips. What types of projects are you currently working on?

MARILYN: I’m working on with Santiago Grivalga of Georgia Tech on smart-energy grids, which are really huge systems that would span entire countries or continents. I continue to work on VLSI-related topics, such as the work on error-aware computing that I pursued with Saibal Mukopodhyay.

I also work with my friend Shuvra Bhattacharyya on architectures for signal-processing systems. As for more unusual things, I’m working on a medical device project that is at the early stages, so I can’t say too much specifically about it.

NAN: Can you provide more specifics about your research into smart energy grids?

MARILYN: Smart-energy grids are also driven by the push for greater efficiency. In addition, renewable energy sources have different characteristics than traditional coal-fired generators. For example, because winds are so variable, the energy produced by wind generators can quickly change.

The uses of electricity are also more complex, and we see increasing opportunities to shift demand to level out generation needs. For example, electric cars need to be recharged, but that can happen during off-peak hours. But energy systems are huge. A single grid covers the eastern US from Florida to Minnesota.

To make all these improvements requires sophisticated software and careful design to ensure that the grid is highly reliable. Smart-energy grids are a prime example of Internet-based control.

We have so many devices on the grid that need to coordinate that the Internet is the only way to connect them. But the Internet isn’t very good at real-time control, so we have to be careful.

We also have to worry about security Internet-enabled devices enable smart grid operations but they also provide opportunities for tampering.

NAN: You’ve earned several distinctions. You were the recipient of the Institute of Electrical and Electronics Engineers (IEEE) Circuits and Systems Society Education Award and the IEEE Computer Society Golden Core Award. Tell us about these experiences.

MARILYN: These awards are presented at conferences. The presentation is a very warm, happy experience. Everyone is happy. These things are time to celebrate the field and the many friends I’ve made through my work.

A Look at Low-Noise Amplifiers

Maurizio Di Paolo Emilio, who has a PhD in Physics, is an Italian telecommunications engineer who works mainly as a software developer with a focus on data acquisition systems. Emilio has authored articles about electronic designs, data acquisition systems, power supplies, and photovoltaic systems. In this article, he provides an overview of what is generally available in low-noise amplifiers (LNAs) and some of the applications.

By Maurizio Di Paolo Emilio
An LNA, or preamplifier, is an electronic amplifier used to amplify sometimes very weak signals. To minimize signal power loss, it is usually located close to the signal source (antenna or sensor). An LNA is ideal for many applications including low-temperature measurements, optical detection, and audio engineering. This article presents LNA systems and ICs.

Signal amplifiers are electronic devices that can amplify a relatively small signal from a sensor (e.g., temperature sensors and magnetic-field sensors). The parameters that describe an amplifier’s quality are:

  • Gain: The ratio between output and input power or amplitude, usually measured in decibels
  • Bandwidth: The range of frequencies in which the amplifier works correctly
  • Noise: The noise level introduced in the amplification process
  • Slew rate: The maximum rate of voltage change per unit of time
  • Overshoot: The tendency of the output to swing beyond its final value before settling down

Feedback amplifiers combine the output and input so a negative feedback opposes the original signal (see Figure 1). Feedback in amplifiers provides better performance. In particular, it increases amplification stability, reduces distortion, and increases the amplifier’s bandwidth.

 Figure 1: A feedback amplifier model is shown here.


Figure 1: A feedback amplifier model is shown.

A preamplifier amplifies an analog signal, generally in the stage that precedes a higher-power amplifier.

IC LOW-NOISE PREAMPLIFIERS
Op-amps are widely used as AC amplifiers. Linear Technology’s LT1028 or LT1128 and Analog Devices’s ADA4898 or AD8597 are especially suitable ultra-low-noise amplifiers. The LT1128 is an ultra-low-noise, high-speed op-amp. Its main characteristics are:

  • Noise voltage: 0.85 nV/√Hz at 1 kHz
  • Bandwidth: 13 MHz
  • Slew rate: 5 V/µs
  • Offset voltage: 40 µV

Both the Linear Technology and Analog Devices amplifiers have voltage noise density at 1 kHz at around 1 nV/√Hz  and also offer excellent DC precision. Texas Instruments (TI)  offers some very low-noise amplifiers. They include the OPA211, which has 1.1 nV/√Hz  noise density at a  3.6 mA from 5 V supply current and the LME49990, which has very low distortion. Maxim Integrated offers the MAX9632 with noise below 1nV/√Hz.

The op-amp can be realized with a bipolar junction transistor (BJT), as in the case of the LT1128, or a MOSFET, which works at higher frequencies and with a higher input impedance and a lower energy consumption. The differential structure is used in applications where it is necessary to eliminate the undesired common components to the two inputs. Because of this, low-frequency and DC common-mode signals (e.g., thermal drift) are eliminated at the output. A differential gain can be defined as (Ad = A2 – A1) and a common-mode gain can be defined as (Ac = A1 + A2 = 2).

An important parameter is the common-mode rejection ratio (CMRR), which is the ratio of common-mode gain to the differential-mode gain. This parameter is used to measure the  differential amplifier’s performance.

Figure 2: The design of a simple preamplifier is shown. Its main components are the Linear Technology LT112 and the Interfet IF3602 junction field-effect transistor (JFET).

Figure 2: The design of a simple preamplifier is shown. Its main components are the Linear Technology LT1128 and the Interfet IF3602 junction field-effect transistor (JFET).

Figure 2 shows a simple preamplifier’s design with 0.8 nV/√Hz at 1 kHz background noise. Its main components are the LT1128 and the Interfet IF3602 junction field-effect transistor (JFET).  The IF3602 is a dual Nchannel JFET used as stage for the op-amp’s input. Figure 3 shows the gain and Figure 4 shows the noise response.

Figure 3: The gain of a low-noise preamplifier.

Figure 3: The is a low-noise preamplifier’s gain.

 

Figure 4: The noise response of a low-noise preamplifier

Figure 4: A low-noise preamplifier’s noise response is shown.

LOW NOISE PREAMPLIFIER SYSTEMS
The Stanford Research Systems SR560 low-noise voltage preamplifier has a differential front end with 4nV/√Hz input noise and a 100-MΩ input impedance (see Photo 1a). Input offset nulling is accomplished by a front-panel potentiometer, which is accessible with a small screwdriver. In addition to the signal inputs, a rear-panel TTL blanking input enables you to quickly turn the instrument’s gain on and off (see Photo 1b).

Photo 1a:The Stanford Research Systems SR560 low-noise voltage preamplifier

Photo 1a: The Stanford Research Systems SR560 low-noise voltage preamplifier. (Photo courtesy of Stanford Research Systems)

Photo 1 b: A rear-panel TTL blanking input enables you to quickly turn the Stanford Research Systems SR560 gain on and off.

Photo 1b: A rear-panel TTL blanking input enables you to quickly turn the Stanford Research Systems SR560 gain on and off. (Photo courtesy of Stanford Research Systems)

The Picotest J2180A low-noise preamplifier provides a fixed 20-dB gain while converting a 1-MΩ input impedance to a 50-Ω output impedance and 0.1-Hz to 100-MHz bandwidth (see Photo 2). The preamplifier is used to improve the sensitivity of oscilloscopes, network analyzers, and spectrum analyzers while reducing the effective noise floor and spurious response.

Photo 2: The Picotest J2180A low-noise preamplifier is shown.

Photo 2: The Picotest J2180A low-noise preamplifier is shown. (Photo courtesy of picotest.com)

Signal Recovery’s Model 5113 is among the best low-noise preamplifier systems. Its principal characteristics are:

  • Single-ended or differential input modes
  • DC to 1-MHz frequency response
  • Optional low-pass, band-pass, or high-pass signal channel filtering
  • Sleep mode to eliminate digital noise
  • Optically isolated RS-232 control interface
  • Battery or line power

The 5113 (see Photo 3 and Figure 5) is used in applications as diverse as radio astronomy, audiometry, test and measurement, process control, and general-purpose signal amplification. It’s also ideally suited to work with a range of lock-in amplifiers.

Photo 3: This is the Signal Recovery Model 5113 low-noise pre-amplifier.

Photo 3: This is the Signal Recovery Model 5113 low-noise preamplifier. (Photo courtesy of Signal Recovery)

Figure 5: Noise contour figures are shown for the Signal Recovery Model 5113.

Figure 5: Noise contour figures are shown for the Signal Recovery Model 5113.

WRAPPING UP
This article briefly introduced low-noise amplifiers, in particular IC system designs utilized in simple or more complex systems such as the Signal Recovery Model 5113, which is a classic amplifier able to obtain different frequency bands with relative gain. A similar device is the SR560, which is a high-performance, low-noise preamplifier that is ideal for a wide variety of applications including low-temperature measurements, optical detection, and audio engineering.

Moreover, the Krohn-Hite custom Models 7000 and 7008 low-noise differential preamplifiers provide a high gain amplification to 1 MHz with an AC output derived from a very-low-noise FET instrumentation amplifier.

One common LNA amplifier is a satellite communications system. The ground station receiving antenna will connect to an LNA, which is needed because the received signal is weak. The received signal is usually a little above background noise. Satellites have limited power, so they use low-power transmitters.

Telecommunications engineer Maurizio Di Paolo Emilio was born in Pescara, Italy. Working mainly as a software developer with a focus on data acquisition systems, he helped design the thermal compensation system (TCS) for the optical system used in the Virgo Experiment (an experiment for detecting gravitational waves). Maurizio currently collaborates with researchers at the University of L’Aquila on X-ray technology. He also develops data acquisition hardware and software for industrial applications and manages technical training courses. To learn more about Maurizio and his expertise, read his essay on “The Future of Data Acquisition Technology.”

High-Voltage Gate Driver IC

Allegro A4900 Gate Driver IC

Allegro A4900 Gate Driver IC

The A4900 is a high-voltage brushless DC (BLDC) MOSFET gate driver IC. It is designed for high-voltage motor control for hybrid, electric vehicle, and 48-V automotive battery systems (e.g., electronic power steering, A/C compressors, fans, pumps, and blowers).

The A4900’s six gate drives can drive a range of N-channel insulated-gate bipolar transistors (IGBTs) or power MOSFET switches. The gate drives are configured as three high-voltage high-side drives and three low-side drives. The high-side drives are isolated up to 600 V to enable operation with high-bridge (motor) supply voltages. The high-side drives use a bootstrap capacitor to provide the supply gate drive voltage required for N-channel FETs. A TTL logic-level input compatible with 3.3- or 5-V logic systems can be used to control each FET.

A single-supply input provides the gate drive supply and the bootstrap capacitor charge source. An internal regulator from the single supply provides the logic circuit’s lower internal voltage. The A4900’s internal monitors ensure that the high- and low-side external FET’s gate source voltage is above 9 V when active.

The control inputs to the A4900 offer a flexible solution for many motor control applications. Each driver can be driven with an independent PWM signal, which enables implementation of all motor excitation methods including trapezoidal and sinusoidal drive. The IC’s integrated diagnostics detect undervoltage, overtemperature, and power bridge faults that can be configured to protect the power switches under most short-circuit conditions. Detailed diagnostics are available as a serial data word.

The A4900 is supplied in a 44-lead QSOP package and costs $3.23 in 1,000-unit quantities.

Allegro MicroSystems, LLC
www.allegromicro.com