Control circuit operating in pulse skip mode and voltage converter having the same

A voltage converter operating in a PSM comprising:

• an output-stage circuit configured for converting an input voltage into an output voltage and generating a feedback voltage related to the output voltage;
• a PWM generation circuit coupled to the output-stage circuit and configured for generating a first signal indicating the feedback voltage condition and a duty-cycle signal in a PWM mode by a first error amplifier;
• a pulse skip circuit coupled to the output-stage circuit and the PWM generation circuit, configured for receiving the first signal, generating a second signal indicating the feedback voltage condition by a second error amplifier, generating a second comparator signal according to the second signal, and comparing the first signal with the second comparator signal to generate a standby signal in PSM, wherein a gain value of the second error amplifier is less than a gain value of the first error amplifier;
• and
• a switch driving circuit coupled to the PWM generation circuit, the pulse skip circuit and the output-stage circuit, and configured for receiving the duty-cycle signal and the standby signal;
• wherein when the standby signal indicates that the first signal is less than the second comparator signal, the switch driving circuit operates in PSM and decreases the duty-cycle signal to generate a control signal to drive the output-stage circuit;
• wherein when the standby signal indicates that the first signal is more than or equal to the second comparator signal, the switch driving circuit operates in the PWM mode and generates the control signal according to the duty-cycle signal to drive the output-stage circuit.

A control circuit operating in a PSM, adapted for a voltage converter and used for converting an input voltage into an output voltage by controlling an output-stage circuit of the voltage converter, wherein the output-stage circuit generates a feedback voltage related to the output voltage, the control circuit comprising:

• a PWM generation circuit coupled to the output-stage circuit and configured for generating a first signal indicating the feedback voltage condition and a duty-cycle signal in a PWM mode by a first error amplifier;
• a pulse skip circuit coupled to the output-stage circuit and the PWM generation circuit, configured for receiving the first signal, generating a second signal indicating the feedback voltage condition by a second error amplifier, generating a first comparator signal according to the first signal and the second signal, and comparing the first comparator signal with a constant voltage signal related to the first signal to generate a standby signal in PSM, wherein a gain value of the second error amplifier is less than a gain value of the first error amplifier;
• and
• a switch driving circuit coupled to the PWM generation circuit, the pulse skip circuit and the output-stage circuit, and configured for receiving the duty-cycle signal and the standby signal;
• wherein when the standby signal indicates that the first comparator signal is less than the constant voltage signal, the switch driving circuit operates in PSM and decreases the duty-cycle signal to generate a control signal to drive the output-stage circuit;
• wherein when the standby signal indicates that the first comparator signal is more than or equal to the constant voltage signal, the switch driving circuit operates in the PWM mode and generates the control signal according to the duty-cycle signal to drive the output-stage circuit.