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Phase-Shifted Full Bridge Converter (Synchronous FETs)

Description

This circuit has a phase shift between the left and right legs on the primary side and provides power to the secondary side only during the overlapping period. Since the duty of each leg is fixed at close to 50%, zero voltage switching (ZVS) operation is possible, which is suitable for high voltage (400VDC series, etc.) and several kW applications. It is often used for EV OBC and server DC-DC. The inductor at primary side is required for ZVS operation.

Overview

- Implementation with SJ MOSFETs (primary) and LV MOSFETs (secondary)
- Zero voltage switching (ZVS)
- Phase shift between both half-bridges for voltage / current control.
- Isolation transformer enables large step-down ratios
- Efficiency around 96%
- Frequency: 100..150 kHz
- SJ MOSFETs with robust & fast body-diode required --> PrestoMOS

Circuit

Circuit

Key Products

Product Category Product family Product Number Feature
Primary Side (HV) 600V SJ MOS PrestoMOS (JNx series) excellent switching behaviour (low Qrr, short Trr)
Secondary Side (LV) 100V MOSFET RQ3P300BH 100V MOSFET in small HSMT8 package
40V MOSFET RS1G300GN 40V MOSFET in HSOP8 package
Gate Driver HV side BM60212FV-C Dual driver, ideal for half- and full-bridge topologies.
LV Side BD85506F Synchronous rectification controller IC

Simulation

Coming soon

Related Topologies

LLC Converter (Full Bride, Synchronous FETs)