Quarter-brick supply delivers big power, fast response
By Bill Schweber -- EDN, March 4, 2004
Vicor is expanding its extensive power-supply line with a family of IBC (intermediate-bus-converter) modules in quarter-brick format that incorporate BCMs (bus-converter modules) and offer high efficiency, low noise, and fast response. You can use these pin-compatible, industry-standard-format devices as single modules for ratings as high as 300W or parallel them to double the output. Designed for 38 to 55V-dc input, the isolated modules are available with nominal outputs in nine distinct voltage values from 3 to 48V dc (Picture).
The vendor says that these modules offer efficiency of at least 95% for the 3V output to better than 97% for the 48V output, partially a result of their zero-current/zero-voltage switching architecture. You can get full power without a heat sink; cooling requirement is just 200 ft/minute (60m/minute) with 55°C airflow. Output current ranges to 100A, so the package uses a special pin design to handle the high current level and IR drop.
The 3.5-MHz switching frequency reduces the size of all reactive components, and the supply needs no output inductor for its serial-path energy storage; further, the requisite transformer is a low-Q, low-cost unit. Despite this operating frequency, noise is just 12 mV. Response to a 100% step change in load is under 1 msec for overall supply-rail integrity. Vicor has priced these IBC modules at about 11 cents per watt (OEM quantities).
Vicor Corp, 1-800-735-6200 www.vicorpower.com.
