Lii Semiconductor Co., Ltd.

Min Zhu

Jie Zhang

Fulong Wang

Xinchun Lin

Lingbo Zheng

The present application relates to a synchronous rectification sampling control circuit, method and chip. The control circuit includes a withstand voltage switch tube Q2, a power supply switch tube Q3, a positive phase power supply driving module, a detection control module, and a negative phase power supply module. The withstand voltage switch tube Q2 includes a withstand voltage source, a withstand voltage grid and a withstand voltage drain, in which the withstand voltage drain is configured to connect a secondary winding power supply circuit in a synchronous rectification circuit of a transformer to obtain a supply voltage and output a positive or negative sampling voltage at the withstand voltage source.

Synchronous rectification sampling control circuit, method and chip

A CCM-based fly-back switching power supply circuit includes: a constant current control circuit, a sampling circuit and a peak current control circuit, wherein a sampling circuit is configured to sample the ON-time of the secondary coil to obtain its duty cycle signal D_SEC, and send the signal to a constant current control circuit; a constant current control circuit is configured to receive the duty cycle signal D_SEC, generate a voltage signal CAC from the duty cycle signal D_SEC and the preset reference voltage signal VREF, convert the voltage signal CAC and the peak current control signal VCST from the peak current control circuit into time signals, and conform a comparison on the time signals to output an adjustment signal CCOUT which is used to initiatively adjust the value of the peak current control signal VCST to cause the fly-back switching power supply circuit output a constant current.

CCM-based fly-back switching power supply circuit and control method thereof

A constant-current output control circuit includes a control module, a first resistor, a capacitor, and an error amplifier; the control module is connected to an adjustable control voltage and a detection signal, and the non-inverting input end of the error amplifier is connected to the reference voltage, the inverting input end of the error amplifier is connected to the first end of the first resistor, the output end of the error amplifier is connected to the circuit to be connected, and the first end of the capacitor is connected to the first end of the first resistor, the second end of the capacitor is connected to the output end of the error amplifier, and the second end of the first resistor is connected to the control module. The design method of the circuit is also disclosed.

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Suzhou, China

Min Zhu