DC Bus Converter Chipset Eyes 48V Systems

Targeting distributed power architectures for 48V-input, 150W board-mounted converters, the dc bus converter chipset includes the IR2085S control IC, two IRF7493 primary-side and two IRF6603 secondary-side HEXFET power MOSFETs, the IRF7380 for primary-side bias, and the IRF9956 for a secondary-side gate clamp. The chips are designed for use as the isolated front end of two-stage distributed architectures with an intermediate bus voltage feeding non-isolated point-of-load (POL) converters. They deliver an efficiency in excess of 96% with an output up to 20A/150W in a circuit measuring 1.7 in2. Said to be the heart of the chipset, the IR2085S has a programmable switching frequency up to 500 kHz. The 80V primary-side MOSFETs in a half-bridge configuration have a combined on resistance of 15 milliohms at 10 VGS, a total gate charge of 31 nC, and a gate-to-drain charge of 12 nC. The 30V secondary-side MOSFETs exhibit an on resistance of 3.9 milliohms at 10 VGS and a thermal resistance of 1°C/W. Pricing for a complete chipset is $7.67 each/10,000. INTERNATIONAL RECTIFIER, El Segundo, CA. (310) 252-7105.