IR Intros IRF6646 and IRF6635 DirectFET Chipset

International Rectifier Corp. (IR, El Segundo, CA) introduced a new DirectFET chipset, the IRF6646 and IRF6635, which maximizes dc bus converter efficiency, when used with its IR2086S full-bridge bus converter IC. The IRF6646 and IRF6635 chipset are targeted at 48 V regulated and 36 V to 60 V input-bridge topologies in isolated dc-dc bus converters; synchronous buck, non-isolated, dc-dc topologies; 18 V to 36 V input forward and push-pull converters for mobile communication; and secondary-side synchronous rectification in regulated output, isolated dc-dc applications.

The new chipset solution consists of six MOSFETs (four in the primary and two in the secondary side) and a single IC, yielding a 46% reduction in power semiconductor part count. Additionally, isolated bus converter dc-dc applications made with the chipset achieve 29% reduced board space and operate with as much as 1.5% better efficiency. The IRF6646 80 V MOSFET has a maximum on-state resistance of 9.5 mΩ, which is tailored for primary-side bridge topologies, and the IRF6635 30 V MOSFET has a maximum on-state resistance of 1.8 mΩ, and is optimized for secondary-side synchronous rectification. The IRF6635 also achieves a low on-state resistance in this form factor by up to 22%.

The IRF6646 and IRF6635 MOSFET synchronous buck chipset is available for $1.37 and $1.50, respectively, in 10,000-unit quantities. Prices are subject to change.