Power Electronics

MOSFETs Improve Efficiency of Bus Converters

From International Rectifier, the IRF6668 80-V and IRF6662 100-V DirectFET MOSFETs reduce system-level power loss as much as 10% in 200-W dc-dc bus converter applications. The low combined on-state resistance and gate charge make these devices suitable primary-side power switches for isolated dc-dc bus converters. When the IRF6662 or IRF6668 are used on the primary side of an unregulated 48-V input, 8-V output, 200-W isolated converter, the power density can be increased by taking advantage of the dual-sided cooling capability of the DirectFET MOSFET packaging technology with the addition of a heatsink. The new DirectFET MOSFETs can be used in either half-bridge dc bus topologies with the IR2085S or in full-bridge dc bus topologies with IR2086S, coupled with secondary-side low voltage DirectFET MOSFETs such as the IRF6635 for a complete, high-efficiency solution. Basic electrical specifications for the MOSFETs are listed in the table.

The 100V IRF6662 and the 80V IRF6668 DirectFET MOSFETs are $0.99 each in 10,000-unit quantities.

Part Number Package VDSS RDS(ON) max. @ VGS = 10 V QG Typical QGD Typical
IRF6668 DirectFET MZ 80 V 15 mΩ 22 nC 7.8 nC
IRF6662 DirectFET MZ 100 V 22 mΩ 22 nC 6.8 nC

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