Sg Micro Corp.

Shoubao Yan

Xiang Yu

Jing Min Xu

Jianchun Chen

Disclosed is a switching power supply circuit and a control circuit and a control method thereof. The control circuit comprises a control unit and a driving unit. The control unit controls the driving unit to provide a driving signal with different driving strengths according to a comparison result between a switching voltage and a preset voltage, so as to adjust a speed of turning the power switch off. By controlling the driving strength of the driving signal, a rising rate of the switching voltage can be improved, a spike of the switching voltage can be reduced, various components in the circuit can be protected from being damaged by the spike, and service life and reliability of the circuit can be improved.

Switching power supply circuit, control circuit and control method thereof

A switching converter and a low-voltage startup circuit is provided. The low-voltage startup circuit includes a comparator and a substrate voltage control module. The comparator performs a comparison between an input voltage and a reference voltage and obtain a voltage detection signal according to a result of the comparison. The substrate voltage control module adjusts a substrate voltage of a main switching transistor according to the voltage detection signal, wherein when the voltage detection signal indicates that the input voltage is lower than/equal to the reference voltage, the substrate voltage control module increases the substrate voltage of the main switching transistor, and then a turn-on threshold voltage of the main switching transistor can be reduced, so that the main switching transistor may be normally turned on when the input voltage is low, and the low-voltage startup capability of the switching converter is improved.

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Beijing, China

Shoubao Yan