Protection circuit of LLC resonant converter and display device

By designing power-down detection, shutdown control, and delayed discharge modules in the protection circuit, the problem of common damage to the upper and lower power transistors caused by rapid power-on and power-off of the LLC resonant converter was solved, thus achieving safe operation of the LLC resonant converter.

CN122118626APending Publication Date: 2026-05-29SHENZHEN SKYWORTH DISPLAY TECH CO LTD
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Patent Information

Application Number
CN202512060489.2
Authority / Receiving Office
CN · China
Patent Type
Applications(China)
Current Assignee / Owner
Filing Date
2025-12-31
Publication Date
2026-05-29

AI Technical Summary

Technical Problem

During rapid power-on and power-off cycles, LLC resonant converters suffer damage to both upper and lower power transistors due to the failure of the resonant cavity to release energy in a timely manner, and there is no effective solution in existing technologies.

Method used

Design a protection circuit including a power-down detection module, a shutdown control module, a delayed power-on module, and a discharge module. By monitoring the reference voltage of the LLC control chip in real time, the circuit detects power failure, forces shutdown, and delays the discharge of resonant cavity energy to ensure that the resonant cavity energy is cleared upon the next restart.

Benefits of technology

This effectively prevents damage to the MOSFET under rapid power-on and power-off conditions, ensuring the safe operation of the LLC resonant converter.

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Abstract

The invention relates to a protection circuit of an LLC resonant converter and a display device, the LLC resonant converter comprises an LLC control chip and a half-bridge power circuit, the protection circuit comprises: a power failure detection module configured to output a power failure detection signal when detecting that a reference voltage is lower than a preset threshold; the shutdown control module is configured to pull down the voltage of the protection pin to be lower than a turn-off threshold value in response to the power failure detection signal, so that the LLC control chip stops outputting the driving signal; the delay startup module is configured to generate a delay signal under the condition that the reference voltage is not lower than a preset threshold value so as to maintain the pull-down state of the protection pin by the shutdown control module during a delay period; and the discharge module is configured to discharge energy in the resonant cavity after the LLC control chip stops outputting the driving signal. The problem of MOS damage caused by rapid startup and shutdown of the LLC resonant converter is solved.
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