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LLC Converter (Full Bride, Synchronous FETs)

Description

The LLC converter is a resonant converter that can achieve ZVS operation (primary side switch) and ZCS operation (secondary side switch) simultaneously. It achieves low noise and high efficiency by generating a sinusoidal current waveform with the switch network and resonant circuit.
This circuit consists of a full-bridge switch circuit on the primary side and a center-tap transformer on the secondary side using FETs instead of diodes. This type of configuration is commonly used for relatively high power (around several kW).

Overview

- Same semiconductor devices
- Series resonance between Cr and Lr
- Lr is sometimes implemented as the leakage inductance of the transformer
- Voltage control is done through frequency high complexity design
- Soft switching is defined by magnetizing inductance Lm, not function of the load.
- Efficiency around 98% suits Titanium!
- Frequency 100..200 kHz

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

Phase-Shifted Full Bridge Converter (Synchronous FETs)