Further gains in MOSFET resistance with asymmetric dual TrenchFET structures

January 17, 2014 // By Paul Buckley
Vishay Intertechnology has introduced a 30 V asymmetric dual TrenchFET power MOSFET in the PowerPAIR 3 x 3 mm package usingTrenchFET Gen IV technology.

Providing 57% lower on-resistance, up to 25% higher power density, and 5% higher efficiency than previous-generation devices in this package size, the Vishay Siliconix SiZ340DT helps to save space and simplify the design of highly efficient synchronous buck converters by combining a high-side and low-side MOSFET in one compact package.

The TrenchFET Gen IV technology of the SiZ340DT uses a high-density design to reduce on-resistance without increasing the gate charge, minimising conduction losses. As a result, the low-side Channel 2 MOSFET of the SiZ340DT offers an on-resistance of 5.1 mOhm at a 10 V gate drive and 7.0 mOhm at 4.5V. The high-side Channel 1 MOSFET features on-resistance of 9.5 mOhm at 10V and 13.7 mOhm at 4.5V.

This latest device is optimised for synchronous buck designs such as DC/DC blocks for system auxiliary power rails, DC/DC bricks, and POL converters. The SiZ340DT can also be used in DC/DC conversion circuitry that supplies power to FPGAs.

In these applications, the device maintains a low gate charge of 5.6 nC for the Channel 1 MOSFET and 10.1 nC for Channel 2. The resulting low on-resistance-times-gate charge -  figure of merit (FOM) for MOSFETs in DC/DC converter applications - reduces conduction and switching losses to improve total system efficiency. With higher efficiency, the SiZ340DT can run 30 % cooler than previous-generation devices at the same output load, or provide increased power density.

For typical DC/DC topologies with 10A to 15A output current and an output voltage below 2V, the compact 3 x 3 mm footprint area of the SiZ340DT saves up to 77 % PCB space compared with using discrete solutions, such as a PowerPAK 1212-8 MOSFET for the high-side and a PowerPAK SO-8 for the low side. Reducing switching losses, the device allows higher switching frequencies beyond 450 kHz to shrink the PCB size, without sacrificing efficiency, by enabling the use of smaller inductors and capacitors.

Vishay; www.vishay.com/doc?62877