The Best of SemiApps

The Ultimate Resource for Building Next-Generation Systems

SemiApps allows electronic design engineers to easily and quickly find product vendors. Each month we bring you our best on-line postings (www.semiapps.com/thismonth).

Readers Choice: The best new application-specific ICs

Among the most popular devices viewed this past month is Fairchild Semiconductor’s Green FPS Power Switch. The device is claimed to be able to simplify design and increases efficiency up to 97% in half-bridge resonant converters of up to 450 W.

Offering a “system-in-a-package” approach that includes everything necessary to build efficient resonant converters, this power switch integrates a pulse-frequency-modulation (PFM) controller with a high-voltage gate driver circuit and two fast-recovery MOSFETs (FRFET). Fairchild also offers soft-start, burst operation, and important protection features into a thermally efficient 9-SIP package.

Aimed at printers, vendor machines, and small appliances are three new motor controller chips from Toshiba’s Electronic Components operation.

Engineering blogs of the month

In one of our most popular blogs, “Nonvolatile Memory Goes Green,” Ramtron International’s Duncan Bennett focuses on the increasingly popular environmental issues that are now hot buttons in our industry.

According to Bennett, strategic marketing manager at Ramton, “Design engineers are consistently trying to lower their products’ power consumption so that they only require one battery throughout their entire lifetime (for instance 25 years).” In what Bennett describes as “a developing trend,” ultra-low-power capabilities are giving way to a new breed of products that do not require a battery at all and are based on the concept of “energy harvesting” (deriving energy from the environment to power the product).

The key to both such categories is the products’ ability to sleep at very low power, so low that the device is essentially shut down because leaving it in sleep mode consumes too much power. Shutting down works as long as the product can remember its state when it reboots. For this, a nonvolatile memory with low operating currents and high write endurance is required.

A memory with these features enables the production of devices that never need to be plugged in and never need new batteries, said Bennett.

Power management is also the focus of another attention-grabbing blog at the site during this past month. In his blog, George A. Hall, staff engineer at Summit Microelectronics, discusses how digital control continues its takeover of power management.

He says there are now new requirements for power management in consumer as well as other applications. With these new requirements, our blogger believes simple analog power conversion is inadequate to address issues related to performance, efficiency and functionality. “I believe merging power management in the analog domain with digital control is the most cost effective way to accomplish system goals, without compromising performance. Typical implementations and system needs can certainly benefit from this versatile technology.”

Hall believes other mandatory functions have evolved out of necessity, referring to the standby mode and the sleep mode that are now required by off-line powered devices to reduce power consumption to a minimum while systems are experiencing limited use or have not been used for a predetermined amount of time. Both functions are similar but entirely different in their impact on the system, and each demands digital monitoring and control to be properly implemented for longer battery use and a “greener world.”

Design Classics Library: Application notes of note and moreAmong the interesting application notes posted on the site come from Maxim Integrated Products. Maxim controls a variable-voltage power supply using its DS1809 pushbutton control device.

Many linear and switched-mode power supplies and voltage regulators use a resistor network as feedback into the regulator to adjust the voltage output. This is typically done either by varying the values of the individual resistors or using a mechanical potentiometer.

This application note discusses controlling a voltage regulator using a digital potentiometer with pushbutton controls. The DS1809 uses a “human interface” to control the voltage regulator.

Marty Gold