Soft turn-off active clamp protection circuit and power system

A soft turn-off active clamp protection circuit, connected with a MOSFET and configured for controlling turn-off of the MOSFET, wherein the circuit comprises a gate connection terminal, a drain connection terminal, a source connection terminal, a discharge capacitor, an overvoltage signal acquisition module, a negative feedback module, a discharge current control module and a turn-off control module;

• the gate connection terminal is connected with a gate of the MOSFET;
• the source connection terminal is connected with a source of the MOSFET;
• the drain connection terminal is connected with a drain of the MOSFET;
• the gate connection terminal, the drain connection terminal and the source connection terminal are connected with each other;
• one end of the discharge capacitor is connected with the gate connection terminal, and the other end of the discharge capacitor is connected with the drain connection terminal;
• the overvoltage signal acquisition module is connected between the source connection terminal and the drain connection terminal;
• the discharge current control module and the turn-off control module are connected in series between the gate connection terminal and the source connection terminal;
• the negative feedback module is connected to the overvoltage signal acquisition module and the discharge current control module;
• the overvoltage signal acquisition module is configured for being turned on when an overvoltage signal is acquired;
• the negative feedback module gives negative feedback to the discharge current control module when the overvoltage signal acquisition module is turned on, and the discharge current control module controls a discharge current of the discharge capacitor according to the negative feedback, thereby controlling an output current of the gate connection terminal;
• and
• the turn-off control module is turned off or turned on according to the intended output of the gate connection terminal.