Shanghai Xinlong Semiconductor Technology Co., Ltd.

Jinlong Xu

Bin Liu

Ruiping Li

Wei Chi

A short-circuit protection circuit, chip and system for a switched-mode power supply are disclosed. The short-circuit protection circuit includes: a sampling module for sampling an input voltage and producing a first voltage from the input voltage; a generation module for generating a second voltage from a reference voltage; a comparison module for comparing the first voltage and the second voltage; and an output module for producing, from a result of the comparison performed by the comparison module, and outputting a control signal for controlling an external power transistor in the event of a short circuit in the switched-mode power supply. According to the present invention, when an output short circuit is detected, a hiccup-mode duty cycle is adjusted according to the input voltage, thus avoiding great energy loss when the input voltage is high and enabling loaded startup or automatic output recovery after the short circuit condition is removed when the input voltage is low.

Short-circuit protection circuit, chip and system for switched-mode power supply

A current limit control circuit and a switched-mode power supply chip incorporating the current limit control circuit are disclosed. The current limit control circuit includes an output current sampling module, a first voltage comparator module, a hysteresis comparator module, a logic control module, a capacitor charging/discharging module and a current limit control module. The capacitor charging/discharging module is configured to charge/discharge a capacitor and thus change its output voltage, and the hysteresis comparator module is configured to produce a current limit control signal which allows the switched-mode power supply to output a high current for a specified period of time. Upon elapse of the period, the power transistor is controlled to cause a low current to be output. This ensures that the demand of a load for a transient current is satisfied while ensuring safe and stable operation of the chip for a long time.

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Shanghai, China

Jinlong Xu