Supertex Class-D driver for high power audio amplifiers

Californian high voltage chip firm Supertex has introduced a Class-D driver for high power audio amplifiers.

"The MD7120 has been optimised for parameters critical to Class-D audio performance such as high efficiency and low EMI," said marketing v-p Ahmed Masood.

"Additionally, this Mosfet driver provides up to a 3.A peak driving current with matched output resistance and channel-to-channel propagation delay for lower total harmonic distortion and noise."

Powered from between 200V and 12V, amplifiers can be built with over 100W output with 90 per cent efficiency.

Dead time matching is ±5ns with rise or fall times under 30ns into a typical 1nF load. Four N-channel output mosfets are required, driven from normal logic level inputs by directly coupled internal level translators.

On-chip is control logic, level translators, a bootstrap-powered high side gate driver and over-temperature, under-voltage and current protection circuits.

"The thresholds of the current protection for both the high and low sides are resistor-programmable," said Supertex.

An associated application note AN-H61 (PDF) describes demo board with a self-oscillating 750kHz second-order modulator using the driver. The board delivers 50W into 8Ω with 0.01 per cent THD+noise from ±35V. Claimed efficiency of the power stage is over 80 per cent at 10 to 20W.

See http://www.supertex.com

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Nanoscale Lithographic Technology: Finer Lines For Microchip

MIT graduate student Chih-Hao Chang of the Department of Mechanical Engineering demonstrates the absence of light diffraction from a frequency-doubled grating on a 100 mm-diameter silicon wafer. The wafer is immersed in water to enable blue-light optical diffraction from the 200 nm-period 'master' grating at the periphery of the wafer, whilst the center of the wafer, where the grating has a 100 nm pitch, exhibits no optical diffraction. Mr. Chang is standing in front of the MIT nanoruler tool which produced the patterns. (Credit: Image courtesy of Massachusetts Institute of Technology)

Their new technique could pave the way for next-generation computer memory and integrated-circuit chips, as well as advanced solar cells and other devices.

The team has created lines about 25 nanometers (billionths of a meter) wide separated by 25 nm spaces. For comparison, the most advanced commercially available computer chips today have a minimum feature size of 65 nm. Intel recently announced that it will start manufacturing at the 32 nm minimum line-width scale in 2009, and the industry roadmap calls for 25 nm features in the 2013-2015 time frame.

The MIT technique could also be economically attractive because it works without the chemically amplified resists, immersion lithography techniques and expensive lithography tools that are widely considered essential to work at this scale with optical lithography. Periodic patterns at the nanoscale, while having many important scientific and commercial applications, are notoriously difficult to produce with low cost and high yield. The new method could make possible the commercialization of many new nanotechnology inventions that have languished in laboratories due to the lack of a viable manufacturing method.

The MIT team includes Mark Schattenburg and Ralf Heilmann of the MIT Kavli Institute of Astrophysics and Space Research and graduate students Chih-Hao Chang and Yong Zhao of the Department of Mechanical Engineering. Their results have been accepted for publication in the journal Optics Letters and were recently presented at the 52nd International Conference on Electron, Ion and Photon Beam Technology and Nanofabrication in Portland, Ore.

Schattenburg and colleagues used a technique known as interference lithography (IL) to generate the patterns, but they did so using a tool called the nanoruler--built by MIT graduate students--that is designed to perform a particularly high precision variant of IL called scanning-beam interference lithography, or SBIL. This recently developed technique uses 100 MHz sound waves, controlled by custom high-speed electronics, to diffract and frequency-shift the laser light, resulting in rapid patterning of large areas with unprecedented control over feature geometry.

While IL has been around for a long time, the SBIL technique has enabled, for the first time, the precise and repeatable pattern registration and overlay over large areas, thanks to a new high-precision phase detection algorithm developed by Zhao and a novel image reversal process developed by Chang.

According to Schattenburg, "What we're finding is that control of the lithographic imaging process is no longer the limiting step. Material issues such as line sidewall roughness are now a major barrier to still-finer length scales. However, there are several new technologies on the horizon that have the potential for alleviating these problems. These results demonstrate that there's still a lot of room left for scale shrinkage in optical lithography. We don't see any insurmountable roadblocks just yet."

The MIT team performed the research in the Space Nanotechnology Laboratory of the MIT Kavli Institute of Astrophysics and Space Research, with financial support from NASA and NSF.

Adapted from materials provided by Massachusetts Institute of Technology.

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Silicon Storage 8051-based MCU with two system management buses

Silicon Storage Technology has added to its FlashFlex family of 8-bit microcontrollers with its first 8051-based MCU to feature two system management buses (SMBus), each supporting up to 400kbit/s data throughput, in a 6x6mm QFN package.

The SST89C58RC supports operating voltages from 2.7V to 5.5V.

According to the supplier, the dual hardware SMBus interfaces let the SST89C58RC act as an intermediary between a host processor and a complex multi-chip A/V subsystem.

The MCU is suitable for bundled applications, shielding the host from low-level interrupts while providing it with a 'virtual' register interface for simplified control and status access.

The SST89C58RC comes with 1kbyte of on-chip RAM and up to 34kbyte of embedded SuperFlash memory.

See http://www.sst.com

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Fairchild Semiconductor FOD07xx Series high speed logic gate Optocoupler

Fairchild Semiconductor brings designers optocoupler devices that deliver a fast and robust isolation interface to ensure low transmission error rates and proven reliability for noisy industrial environments.

The FOD0721, FOD0720 and FOD0710 are logic gate optocouplers that isolate the logic control circuitry from the transceiver at the bus interface level. Since industrial systems are susceptible to noise transients, FOD07xx's high noise immunity coupled with its high speed (25Mbps) minimises the chance of transmission errors or system failures. These products meet high reliability requirements and are qualified according to the UL1577 standard. The FOD07xx series is ideal for industrial communication standards such as Profibus, DeviceNet, CAN and RS485.

The FOD07xx series are packaged in Fairchild's patented Optoplanar co-planar packaging, which claims to reduce package capacitance by more than 30 per cent compared to other products. This low capacitance package leads to a guaranteed 20kV/µs minimum Common Mode Noise Rejection rating that is double that of alternative products, allowing the FOD07xx series to operate in noisy industrial environments. 

The FOD07xx series is part of Fairchild's optoelectronic portfolio that includes high-speed optocouplers, gate drive optocouplers, snubberless triac driver, photo transistors, and infrared components. The FOD0721, FOD0720 and FOD0710 use lead-free (Pb-free) terminals and have been characterised for moisture sensitivity in accordance with the Pb-free reflow requirements of the joint IPC/JEDEC standard J-STD-020.

All Fairchild's products are designed to meet the requirements of the EU's directive on the restriction of the use of certain substances (RoHS).

Price (each 1000pcs):

• $2.67 for FOD0721
• $2.44 for FOD0720
• $2.21 for FOD0710

Availability:

Samples are available now with delivery 6 weeks ARO

More information: http://www.fairchildsemi.com.

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Renesas Technology high-frequency power MOSFETS

Renesas Technology's latest high-frequency power Mosfets, designed for use in the transmitter power amplifier of handheld wireless equipment, the devices achieve 60% added power efficiency in the RQA0010 at 3.6V and 55% in the RQA0014.

In particular, when a two-stage amplifier is implemented by driving the RQA0010 with the output of the RQA0014, the circuit achieves the industry's highest level of performance: a 1.2W output at 3.6V.

With high ESD immunity, the devices maintain their high-efficiency characteristics at 20kV and over and achieve ESD immunity level 4. 

The ESD immunity level is measured with a test that verifies that a static aerial discharge applied to the antenna of a wireless device does not affect that device and that simulates the discharges that actually could occur from a person or metal object as required by the IEC61000-4-2 standard.

The following levels are stipulated by this standard. Level 1: 2kV, level 2: 4kV, level 3: 8kV, level 4: 15kV.

The RQA0014 is mainly for use as a transmitter power amplifier driver and the RQA0010 is suitable for use as a power amplifier.

See http://www.renesas.eu

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Graphene Used To Create World's Smallest Transistor

Dr Ponomarenko, who carried out this work, shows his research sample: graphene quantum dots on a chip. (Credit: Image courtesy of University of Manchester)

Reporting their peer-reviewed findings in the journal Science, Dr Kostya Novoselov and Professor Andre Geim from The School of Physics and Astronomy at The University of Manchester show that graphene can be carved into tiny electronic circuits with individual transistors having a size not much larger than that of a molecule.

The smaller the size of their transistors the better they perform, say the Manchester researchers.

In recent decades, manufacturers have crammed more and more components onto integrated circuits. As a result, the number of transistors and the power of these circuits have roughly doubled every two years. This has become known as Moore's Law.

But the speed of cramming is now noticeably decreasing, and further miniaturisation of electronics is to experience its most fundamental challenge in the next 10 to 20 years, according to the semiconductor industry roadmap.

At the heart of the problem is the poor stability of materials if shaped in elements smaller than 10 nanometres*  in size. At this spatial scale, all semiconductors -- including silicon -- oxidise, decompose and uncontrollably migrate along surfaces like water droplets on a hot plate.

Four years ago, Geim and his colleagues discovered graphene, the first known one-atom-thick material which can be viewed as a plane of atoms pulled out from graphite. Graphene has rapidly become the hottest topic in physics and materials science.

Now the Manchester team has shown that it is possible to carve out nanometre-scale transistors from a single graphene crystal. Unlike all other known materials, graphene remains highly stable and conductive even when it is cut into devices one nanometre wide.

Graphene transistors start showing advantages and good performance at sizes below 10 nanometres - the miniaturization limit at which the Silicon technology is predicted to fail.

"Previously, researchers tried to use large molecules as individual transistors to create a new kind of electronic circuits. It is like a bit of chemistry added to computer engineering", says Novoselov. "Now one can think of designer molecules acting as transistors connected into designer computer architecture on the basis of the same material (graphene), and use the same fabrication approach that is currently used by semiconductor industry".

"It is too early to promise graphene supercomputers," adds Geim. "In our work, we relied on chance when making such small transistors. Unfortunately, no existing technology allows the cutting materials with true nanometre precision. But this is exactly the same challenge that all post-silicon electronics has to face. At least we now have a material that can meet such a challenge."

"Graphene is an exciting new material with unusual properties that are promising for nanoelectronics", comments Bob Westervelt, professor at Harvard University. "The future should be very interesting".

*One nanometre is one-millionth of a millimetre and a single human hair is around 100,000 nanometres in width.

A paper entitled "Chaotic Dirac Billiard in Graphene Quantum Dots" is published in April 17 issue of Science. It is accompanied by a Perspective article entitled "Graphene Nanoelectronics" by Westervelt. 

Adapted from materials provided by University of Manchester.

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Ramtron introduces first 2MB Serial F-RAM

Ramtron International Corporation, a developer and supplier of nonvolatile ferroelectric random access memory (F-RAM) and integrated semiconductor products, has unveiled the industry's first 2-megabit (Mb) serial F-RAM memory in an 8-lead TDFN (5.0 x 6.0 mm) package. 

Manufactured on an advanced 130 nanometer CMOS process, the FM25H20 is a high-density nonvolatile F-RAM memory that operates at low power and features a high-speed serial peripheral interface (SPI).  The 3-volt, 2Mb serial F-RAM writes at maximum bus speed with virtually unlimited endurance for greater data collection capacity in a tiny package, enabling system designers to reduce costs and board space in a range of advanced applications including meters and printers.

The FM25H20 is an ideal replacement for serial Flash in sophisticated electronic systems that require low power and minimal board space.  These include portable medical devices such as hearing aids, which are essentially mini data processors with limited space and low power budgets.  F-RAM benefits over Flash include significantly lower operating currents, faster writes, and write endurance that is orders of magnitude greater than Flash. 

"The 2Mb serial F-RAM is a natural extension for our metering and printer customers who want to increase data collection capacity in their next-generation applications without increasing board space.  The FM25H20 offers our half megabit serial F-RAM customers quadruple the memory in the same small footprint," explains Duncan Bennett, Ramtron Strategic Manager.  "In addition to enhancing existing systems, this technological development moves F-RAM into a range of new markets that require a low-power memory in a very constrained space, such as portable medical devices."

Product Features

The FM25H20 is organized as a 256K x 8 bit nonvolatile memory that reads and writes at bus speed up to 40MHz, with essentially unlimited endurance, 10-year data retention, and low operating currents.  The device incorporates an industry-standard SPI interface that optimizes F-RAM's high-speed write capability.  A hardware and software write protection feature is also included on the FM25H20 to prevent inadvertent writes and data corruption. 

The 2Mb serial F-RAM operates at low power, drawing less than 10 milliamps for reads/writes at 40MHz, 80 microamps (typical) in standby, and 3 microamps (typical) in ultra-low-current sleep mode.  Pin-compatible with equivalent serial Flash devices, but far superior because of its fast access time, high endurance and low operating current, the 2Mb F-RAM operates from 2.7 to 3.6 volts over the entire industrial temperature range (-40 degrees C to +85 degrees C). For more product information, visit '100">'www.ramtron.com/products/nonvolatile-memory/serial-product.aspx?id=100.

About the Advanced 130 Nanometer Process

The FM25H20 is based on Texas Instruments' proven 130 nanometer (nm) CMOS manufacturing process.  Only two additional mask steps have been used to embed the nonvolatile F-RAM module within the standard CMOS 130nm logic process.

Pricing and Availability

Samples of the FM25H20 are available in an 8-pin TDFN package that is RoHS-compliant and footprint-compatible with 8-pin SOICs.  Pricing starts at $10.20 for quantities of 10,000 units.

Further information

For more details, contact Ramtron International on +1 514 871 2447 or framinfo@ramtron.com.

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