US Patent No. 9,318,962

CIRCUITS AND METHODS FOR REDUCING OUTPUT VOLTAGE OVERSHOOT OF SWITCH MODE POWER SUPPLY


Patent No. 9,318,962
Issue Date April 19, 2016
Title Circuits And Methods For Reducing Output Voltage Overshoot Of Switch Mode Power Supply
Inventorship Chao Gao, Shanghai (CN)
Pingan Zhao, Shanghai (CN)
Chao Chen, Shanghai (CN)
Assignee BCD Semiconductor Manufacturing Limited, Shanghai (CN)

Claim of US Patent No. 9,318,962

1. A switching mode power supply (SMPS), comprising:
a transformer having:
a primary winding for coupling to an input power source;
a secondary winding for providing an output voltage of the SMPS; and
an auxiliary winding;
a power transistor coupled to the primary winding;
a primary side control circuit coupled to the auxiliary winding and the power transistor, the primary side control circuit
being configured to regulate the output of the SMPS by controlling the power switch in response to a feedback voltage signal
that is representative of an output of the SMPS; and

a secondary-side control circuit coupled to the secondary winding and being configured to cause the output voltage of the
SMPS to discharge when the output voltage of the SMPS is higher than a first overvoltage reference voltage;

wherein the secondary-side control circuit comprises a discharge control circuit having a power supply terminal coupled to
the output voltage of the SMPS, the discharge control circuit being configured to issue a discharge signal;

wherein the discharge control circuit comprises a comparator having a negative input coupled to the second reference voltage
and a positive input coupled to a third reference voltage that is lower than the second reference voltage, the comparator
also having a power supply terminal coupled to the output voltage of the SMPS.