Switching mode power converter with pulse skipping and control method thereof

A method for controlling a pulse width modulate (PWM) controller of a power converter to skip pulse(s), comprising:

• in a switching cycle of the power converter,
• charging a capacitor with a current equal to α(VIN−VOUT) when a PWM signal of the PWM controller is high, α being a pre-configured constant, and the power converter having an input voltage VIN and an output voltage VOUT;
• discharging the capacitor with a current equal to α(−VOUT) when the PWM signal of the PWM controller is low;
• and
• when detecting that a voltage across the capacitor decreases, during discharging of the capacitor, to be less than a skip threshold before the switching cycle ends, triggering the PWM controller to skip pulse(s).

An apparatus comprising:

• a power converter comprising a power switch and an inductor that are connected between an input node and an output node of the power converter, the input node having an input voltage VIN and the output node providing an output voltage VOUT;
• a pulse width modulate (PWM) controller coupled to the power converter and configured to control the power converter to operate in a PWM mode;
• and
• a control circuit coupled to the PWM controller, the control circuit comprising:
• a current source;
• and
• a capacitor connected between the current source and a ground, wherein the current source is configured to charge the capacitor with a current equal to αVIN or α(VIN−VOUT) when a PWM signal of the PWM controller is high, and to discharge the capacitor with a current equal to α(−VOUT) or α(VIN−VOUT) when the PWM signal of the PWM controller is low, α being a pre-configured constant;
• and
• wherein the control circuit is configured to trigger the PWM controller to skip switching on the power switch for pulse(s) when a voltage at a common node of the current source and the capacitor decreases, during discharging of the capacitor, to be less than a skip threshold before a present switching cycle of the power converter ends.