Power transistor overcurrent protection circuit

A power transistor overcurrent protection circuit, applied to a power transistor control circuit, the power transistor control circuit comprising a load and a controlled power transistor for controlling the load to work or not to work, the power transistor overcurrent protection circuit comprising:

• an overcurrent detection circuit, connected to the controlled power transistor;
• the overcurrent detection circuit being configured to detect whether there is an overcurrent flowing in the controlled power transistor;
• wherein if there is an overcurrent flowing in the controlled power transistor, an output terminal of the overcurrent detection circuit outputs an overcurrent signal;
• if there is no overcurrent flowing in the controlled power transistor, the output terminal of the overcurrent detection circuit outputs a normal signal;
• a timing control circuit, connected to the output terminal of the overcurrent detection circuit;
• wherein when the timing control circuit is powered on, an output terminal of the timing control circuit outputs an ON signal;
• after the timing control circuit is powered on, the signal output from the output terminal of the timing control circuit is controlled according to the signal output from the output terminal of the overcurrent detection circuit;
• if the output terminal of the overcurrent detection circuit outputs the overcurrent signal, the output terminal of the timing control circuit continuously outputs an OFF signal within a set time and outputs the ON signal again after reaching the set time;
• if the output terminal of the overcurrent detection circuit outputs the normal signal, the output terminal of the timing control circuit keeps outputting the ON signal;
• an enable control circuit, connected to the output terminal of the timing control circuit and a gate of the controlled power transistor;
• the enable control circuit being configured to control the controlled power transistor to be turned on or off, the enable control circuit being controlled by the signal output from the output terminal of the timing control circuit and an enable signal;
• wherein when the enable control circuit receives the OFF signal output from the timing control circuit, the enable control circuit turns off the controlled power transistor;
• when the enable control circuit receives the active enable signal and the ON signal output from the timing control circuit at the same time, the enable control circuit turns on the controlled power transistor;
• wherein the timing control circuit is connected to the overcurrent detection circuit through a signal conversion circuit;
• the overcurrent signal is a low-level signal, the normal signal is a high-level signal;
• an input terminal of the signal conversion circuit is connected to the output terminal of the overcurrent detection circuit;
• the signal conversion circuit is configured to perform a level conversion on the signal output from the output terminal of the overcurrent detection circuit, the signal conversion circuit converts the high-level normal signal into a low-level hold signal to be output to an input terminal of the timing control circuit, the signal conversion circuit converts the low-level overcurrent signal into a high-level trigger signal to be output to the input terminal of the timing control circuit;
• the input terminal of the timing control circuit is connected to an output terminal of the signal conversion circuit, after the timing control circuit is powered on, if the input terminal of the timing control circuit receives the hold signal, the output terminal of the timing control circuit keeps outputting the ON signal;
• if the signal received by the input terminal of the timing control circuit changes from the hold signal to the trigger signal, the output terminal of the timing control circuit continuously outputs the OFF signal within the set time and outputs the ON signal again after reaching the set time.