Control method and device for low current started and low voltage protection circuit

A started and low voltage protection circuit comprises a starting voltage detection module and a state latch with delayed voltage. The voltage detection module is started and used for detecting power supply voltage of a chip. When the power supplying voltage is higher than an upper limit voltage threshold value, an enabling end outputs an enabling signal. A pulse width modulation (PWM) control module of the chip is started to allow the chip to work normally. When the power supply voltage is lower than a lower limit voltage threshold, the enabling signal closes the PWM control module of the chip. When the power supply voltage is lower than the lower limit voltage threshold and the enabling signal closes the PWM control module of the chip, the state latch with the delayed voltage achieves the function of low voltage protection. According to the fact that a sub-microampere level starting and low voltage protection circuit is integrated in the chip of a switch power source, power consumption during starting of a resistor by a power source system of the PWM control chip with the circuit applied and integrated is reduced, design difficulty of a low stand-by power consumption electric system is reduced, and conversion efficiency of the power source system is improved.