The invention provides a mixed switch power converter, comprising a reference
voltage and
reference current generation unit, a PWM / PFM
control unit, a power switch driving unit, a power switch and output circuit, and an auto-switch
control circuit. The reference
voltage and
reference current generation unit is used for generating a reference
voltage signal and a
reference current signal; the PWM / PFM
control unit is used for obtaining a voltage feedback
signal and a current feedback signal, receiving the reference voltage signal and the reference current signal, outputting a first detection signal and a voltage detection signal and outputting a PWM / PFM
control logic signal according to a received working
model selection signal; the power switch driving unit is used for receiving the
control logic signal and outputting a driving signal; the power switch and output circuit is turned on and turned off according to the driving signal; and the auto-switch
control circuit is used for receiving the first detection signal and the voltage detection signal, counting the first detection signal and the voltage detection signal in a predetermined time and outputting the
mode selection signal when the counting result reaches a predetermined threshold value. The invention also provides the auto-switch
control circuit. The invention can improve the
transfer efficiency and the anti-interference performance of the converter within the whole load range.