Patent ID: 9484802
Filing Date: 2016-11-01
CPC Classification: H02M

Claim Text:
1. A soft-off control circuit for controlling a soft-off procedure of a power converter, wherein the power converter comprises a main switch and is configured to receive an input voltage and to provide an output voltage based on driving the main switch to switch on and off, and wherein the power converter further comprises a soft-start/soft-off pin configured to provide a variable reference signal; the soft-off control circuit comprising: a first input terminal configured to receive the input voltage of the power converter; a second input terminal configured to receive an enable signal, wherein the enable signal has a first enable state for controlling the power converter to shut off and start the soft-off procedure and a second enable state for controlling the power converter to power on; a third input terminal configured to receive an over-voltage threshold, wherein the over-voltage threshold is designed to indicate an over-voltage of the input voltage during the soft-off procedure; and an output terminal configured to provide a soft-off control signal; wherein the soft-off control circuit is configured to generate the soft-off control signal at least based on the enable signal, the input voltage and the over-voltage threshold, and wherein when the enable signal is at the first enable state, the soft-off control signal is configured to control the variable reference signal to increase when the input voltage is higher than the over-voltage threshold, and to control the variable reference signal to decrease when the input voltage is lower than the over-voltage threshold.