The invention provides a no-load protection circuit controlled in a
hysteresis current mode and a control method of the no-load protection circuit. The no-load protection circuit comprises an
MOSFET and a current detection
resistor. The inverting input end of the
hysteresis operational amplifier is connected to the
voltage detection point of the current detection
resistor, the non-inverting input end of the
hysteresis operational amplifier is connected to the output end of the
error amplifier, and the output end of the hysteresis
operational amplifier is connected to the grid
electrode of the
MOSFET; the non-inverting input end of the
error amplifier is connected to a reference
voltage, the inverting input end of the
error amplifier is connected to a feedback
voltage, and the output end of the error
amplifier is connected to the non-inverting input end of the hysteresis operational
amplifier and connected to the compensation
capacitor; one end of the compensation
capacitor is connected to the output end of the error
amplifier, and the other end is grounded; the feedback
resistor is connected in series between the output voltage and the ground and is used for dividing the output voltage to obtain feedback voltage; the hysteresis voltage and the compensation voltage are compared through the hysteresis operational amplifier, the on-off state of the
MOSFET is controlled, transmission of input energy is adjusted, and stability and no-load protection of the output voltage are achieved.