Low ON-resistance High-voltage MOSFETs Featuring Ultra-fast Reverse Recovery
and High-speed Switching

Semiconductor manufacturer ROHM Co., LTD., has announced the development of a new lineup of high voltage power MOSFETs featuring unparalleled performance^*. Optimized for virtually any application requiring bridge circuits, including LCD TV backlight inverters, motor drivers, and switching power supplies, the F Series incorporates a novel trap level structure for superior reverse recovery times.

As the market for more energy-efficient LCD TVs and electronic devices increases comes a greater demand for more efficient transistors and other semiconductor components used in the power supplies, along with a need to reduce component count for greater miniaturization. Today, most high-voltage MOSFETs in the 500V to 600V class have adopted a 'super junction' structure that offers faster switching speeds and lower ON-resistance compared to conventional planar structures. However, this super junction structure often suffers from slow internal diode reverse recovery times (trr). To address this it has been customary to connect a fast recovery diode (FRD) in parallel between the Drain and source to increase high-frequency tracking performance when used in bridge circuits and other applications where a regeneration current is fed to the MOSFET's internal diode.

ROHM's new F Series uses the industry's first super junction MOSFET to form local trap levels inside elements in order to shorten reverse recovery times, successfully reducing this important metric from 160ns to 70ns, resulting in an improvement of approximately 60% compared to normal super junction MOSFETs. Although the formation of trap levels inside elements to reduce reverse recovery times has been previously known it has been prohibitively difficult to achieve in a super junction structure. Until now. ROHM has successfully developed the world's first super junction MOSFET with internal local trap levels, eliminating the need to add FRDs, simplifying design while contributing to greater miniaturization and increasing the range of operating frequencies.

^*Based on a comprehensive evaluation of on-resistance, switching speed, and internal diode reverse recovery time (trr).

• F Series Key Features

1. Shortened reverse recovery times due to trap level formation (60% less than conventional designs)
2. High-speed switching: RDS(on) × Qgd = 7.3Ω / nC
3. Low ON-resistance: 4.3Ω / mm²

• Circuit Examples

• Terminology

• Bridge circuit
  A circuit that alternates between ON and OFF states with switching devices split between High and Low sides. Variations include half- and full-bridge types.
• Planar structure
  Also known as a D-MOS structure, characterized by the formation of double-diffused P and N layers on the surface of a silicon wafer.
• Super junction structure
  A structure characterized by a regular array of vertical P/N junctions on a silicon wafer.
• Reverse recovery time (trr)
  The time that reverse current flows when the voltage in a MOSFET's internal diode changes from forward to reverse direction.
• Trap level
  An energy level for reducing carrier storage.

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