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Power MOSFETs for communication systems

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article image New power MOSFETs for 48 Volt networking and communications systems.

INTERNATIONAL Rectifier (IR) has launched 100V-rated IRF7495 and 80V-rated IRF7493 N-channel HEXFET power MOSFETs optimised for isolated full-bridge or half-bridge topology DC/DC converters used in telecommunications systems.

The IRF7495 and IRF7493 have very low device on-resistance and very low gate-to-drain charge, making them ideal for converter switching frequencies up to 500kHz.

IR's latest trench design enhances MOSFET on-resistance and gate charge performances, increasing efficiency that results in 10°C cooler junction temperatures, compared with competing devices. This performance is achieved when the devices are used on the primary side of a 48V bus converter solution.

Lower junction temperatures mean better reliability which is important in today's networking and communications infrastructure.

The IRF7495 is designed for half-bridge and full-bridge topologies in universal telecom input voltage range (36V to 75V) systems, and features as much as 17% lower combined on-state resistance, RDS(on), and gate charge, QG figure of merit compared with competing devices.

The IRF7493 is optimised for half-bridge and full-bridge topologies in reduced ETSI (European Telecom Spec) range (36V to 60V) or regulated 48V systems.

The IRF7493 demonstrates as much as 7% lower combined on-state resistance and gate charge figure of merit, compared with similar devices.

The IRF7493 is a part of IR's new DC bus converter chip set for isolated two-stage distributed power architectures (DPA) for 48V-input systems, where second stage point-of-load (POL) converters generate a tightly regulated load voltage from a non-regulated input voltage.

Two-stage DPA schemes do not require a tightly regulated intermediate bus voltage, since the POL will typically accept a relatively wide input voltage, and the POL provides the needed regulation to the load.

These devices can be used to reduce overall power loss in 150W active ORing applications versus standard diode solutions by as much as 90%. This is because the effective on-state resistance creates much less dc loss than the forward voltage of an ORing diode.

Package size is also reduced to an SO-8 from a bulky D2Pak that is typically used with a diode ORing solution to handle the power dissipation.

The new devices are suitable for 48V hot-swap applications, and can also be used as synchronous rectifiers for regulated 12V to 24V output voltages, where low on-state resistance is key to improving performance.

The devices provide between 5-10% better on-state resistance compared with similar competing devices.

"The new SO-8 packaged MOSFETs have low gate charge for low switching losses, and minimised overall on-state resistance for reduced conduction losses," Stephen Tsang, senior vice president of sales at IR said.

"By selecting the new 80V and 100V IR devices, engineers will be able to improve DPA architecture used in high-performance netcom systems, including isolated converters, active ORing and hot swap circuits."

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