US Patent 11469668 Step-up switching converter and control circuit and method thereof

A control circuit and control method for controlling a step-up switching converter. The control circuit has an ultra-low voltage regulation module used to generate a control signal based on an output voltage feedback signal and an input voltage signal. When the input voltage signal is smaller than an ultra-low voltage threshold, the control signal controls a high side switch of the step-up switching converter off and controls a low side switch of the step-up switching converter to perform on and off switching. Meanwhile, a parasitic diode of the high side switch is on once the low side switch is off.