Saturday, August 24, 2013

Power resistors offer superior high frequency performance

Riedon's new family of non-inductive power resistors is designed to achieve superior performance in high frequency applications and high speed pulse circuits.

The PF family of TO-style resistors all use an advanced power film formed on a heat conducting alumina substrate that is metalised and soldered to a heat dissipating copper plate tab, enabling excellent thermal resistance.

The various package configurations, listed below, cover power ratings from a few Watts up to 600W in both through hole and surface mountings.

The PF1260 is available in an epoxy-moulded TO-126 leaded package, with resistances in the range of 0.01 to 51kO, tolerances from ±1%, a temperature coefficient from ±50ppm.

The PF2200 and PF2470 offer a similar specification but with dissipation up to 50 and 140W respectively in leaded TO-220 and TO-247 packages.

The PF2270 uses the screw-terminal TO227 style package to handle up to 300W, when attached to an appropriate heatsink and subject to temperature derating.

Finally, the PFS35 provides a solution for surface mounting, using a TO-263 housing (D-Pak) to provide 35W dissipation when used with a heatsink or 2W with a simple solder pad.

AMD pushes performance of R-Series cpus

AMD is expanding its Embedded R-Series to include a new range of dual and quad core cpus.

Scaling from 2.2 to 3.2GHz and with Thermal Design Power (TDP) ranging from 17 to 35W, the
devices are targeted at applications that require high performance x86 compute, such as network attached storage.

AMD claims they offer up to 2.5x greater performance per dollar compared to Intel i3 processors.

"There is a need for a greater variety of processor and graphics options in several market segments ranging from storage to digital signage and gaming to meet ever growing performance requirements," said Kamal Khouri, director of embedded products for AMD.

"These new choices offer higher compute and graphics throughput plus compelling total cost of ownership for the embedded market."

As well as the new cpus, AMD is launching a new discrete gpu promotional programme. This, it says, will provide customers with both a cpu and discrete gpu for savings of up to 20%.

Friday, August 23, 2013

Cree has GaN transistors for military applications

Cree has released two new gallium nitride (GaN) high electron mobility transistors (HEMTs), suitable for use in 1.2 to 1.4GHz L-Band radar amplifier systems.

The 250W CGHV14250 and the 500W CGHV14500 are said to feature the highest known L-Band efficiency performance at 85°C, as well as high power gain performance and wide bandwidth capabilities.

According to Cree, the transistors enhance the performance of band specific applications ranging from UHF to 1800MHz, including tactical air navigation systems and friend or foe systems.

Based on the company's 50V 0.4µ GaN on SiC foundry process, the GaN HEMTs are internally pre-matched on the input, and are available in ceramic/metal flange and pill packages that are said to be much smaller than competing gallium arsenide (GaA) or silicon (Si) rf technology, enabling enhanced design flexibility.

The CGHV14250 features 330W typical output power, 18dB power gain and 77% typical drain efficiency. The CGHV14500, meanwhile, features 500W typical output power, 17dB power gain and 70% typical drain efficiency.

Both of the devices feature 0.3dB pulsed amplitude droop.

2A µModule regulator configurable as a step down or an inverter

Linear Technology has unveiled the LTM8050, 2A µModule regulator that is protected against input surges up to 60V and can be configured as a step down or an inverting (i.e. negative output) converter.

With 60V input voltage protection, the LTM8050 can be used safely in applications where the main power bus may be susceptible to large voltage spikes or deviations. Examples include automotive, avionics, factory automation, heavy equipment, transportation, robotics and industrial systems.

The module's operating input voltage is from 3.6 to 58V (60Vmax) and the output is adjustable with one resistor from 0.8 to 24V. When configured as an inverter, the output is adjustable from -0.8 to -24V.

The LTM8050 also includes an inductor, dc/dc regulator, power FETs, and the compensation circuitry, all housed in a 9 x 15 x 4.92mm BGA package.

Thursday, August 22, 2013

Water Chip

Although various alternative technologies are being developed, the large-scale desalination of seawater typically involves forcing it through a membrane that allows the water to pass through, but that traps the salt. These membranes can be costly, they can get fouled, and powerful pumps are required to push the water through. Now, however, scientists from the University of Texas at Austin and Germany’s University of Marburg are taking another approach. They’ve developed a chip that separates salt from water.

The prototype plastic “water chip” contains a microchannel that branches in two, and utilizes a process known as electrochemically mediated seawater desalination.

That process begins with seawater being run into the microchannel, and a 3-volt electrical current being applied. This causes an electrode embedded at the branching point of the channel to neutralize some of the chloride ions in the water, which in turn increases the electrical field at that point in the channel. That area of increased current, called an ion depletion zone, diverts the salt to one branch in the channel while allowing the water to continue down another.

When the electrical current is applied, salt tagged with a fluorescent tracer flows up one branch in the channel (left) – when the current is shut off, the salt flows down both branches

In its present form, the system can run on so little energy that a store-bought battery is all that’s required as a power source. Two challenges still need to be overcome, however.

First of all, the chip currently only removes 25 percent of the salt from the water – 99 percent must be removed in order for seawater to be considered drinkable. Secondly, the system must be scaled up in order to be practical. It presently produces about 40 nanoliters of desalted water per minute. That said, the scientists are confident that with further research, they can rectify both issues.

The system is being developed through spin-off company Okeanos Technologies.