FROM EDN EUROPE: 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 1/8-size "brick" converters for each of the voltage rails, each converter will cost more than €60. Lambda proposes an alternative: a higher power ½-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 the ½-brick module will cost €90 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 favourable 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 will 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, with a settling time of 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 1/8-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.