Intermediate-bus power distribution ups cost-effectiveness

In a distributed power architecture, argues power-supply-manufacturer Lambda, you can achieve considerable cost and efficiency savings by using an intermediate-bus architecture. The company sketches a comparison between two ways of achieving 5, 3.3, 2.5, and 1.8V from a 48V main distribution bus. If you use isolated one-eighth-size "brick" converters for each of the voltage rails, each converter will cost more than $65. Lambda proposes an alternative: a higher power half-brick converter that produces 5V from the 48V line, and nonisolated converters that go from 5V to 3.3, 2.5 and 1.8V. Lambda estimates that the half-brick module will cost approximately $100 and is introducing its Tarka series of converters for the nonisolated, point-of-load function. These converters would cost less than $15 each, providing a favorable price comparison.

The first in the series is the PL10, a 50.8×12.5×7.5-mm SIP that will deliver as much as 10A at 0.9 to 3.3V, from a 3 to 5.5V input with a 33W maximum power figure (Picture). The converters offer peak efficiency of 94%, use synchronous rectification and 300-kHz operation, are current-limited and short-circuit-protected, and offer overtemperature protection. They operate open-circuit and do not require a minimum load. At 3.3V, regulation in response to a 50 to 100% load step change is 80 mV, and settling time is 40 µsec. Lambda will follow the PL10 with products for other voltage ranges, including one for as much as 13.2V and a 15A-rated version.

Aiming for single-source capability for the intermediate-bus concept, Lambda is also introducing a 58.4×9×22.7-mm one-eighth-brick unit that will deliver 12V from a nominal 48V distribution bus, as well as a range of other voltages. Power ratings are 66W maximum.

Coutant Lambda, +44 1271 856600, www.lambda-gb.com.