Switching converter having audible noise suppression and conversion control circuit and method thereof

A conversion control circuit for use in a switching converter, wherein the switching converter includes at least one switch which is configured to operably switch an inductor, to convert an input power to an output power;

• the conversion control circuit comprising:
• a modulation circuit, which is configured to operably execute a pulse width modulation according to a feedback signal related to the output power and a reference signal, to generate a modulation trigger signal;
• a time calculation circuit, which is configured to operably generate a pulse width modulation (PWM) signal according to the modulation trigger signal, and which is configured to operably calculate an ON-time or an OFF-time of the PWM signal, wherein the at least one switch is controlled to switch according to the PWM signal and according to a zero current signal generated by a zero current detector that detects a current related to the output power;
• and
• a time adjustment circuit, which is configured to operably generate a time adjustment signal according to a first clock signal related to the PWM signal, wherein when the switching converter operates in a discontinuous conduction mode (DCM) and a switching frequency of the PWM signal is lower than a predetermined frequency threshold, the time adjustment signal is configured to operably adjust the ON-time or the OFF-time in a random or a pseudo-random fashion;
• wherein when the switching converter operates in a continuous conduction mode (CCM), the switching frequency is kept as a constant.

A control method configured to control a switching converter, wherein the switching converter includes at least one switch, which is configured to operably switch an inductor, to convert an input power to an output power;

• the control method comprising following steps:
• executing a pulse width modulation according to a feedback signal related to the output power and a reference signal, to generate a modulation trigger signal;
• generating a pulse width modulation (PWM) signal according to the modulation trigger signal, and calculating an ON-time or an OFF-time of the PWM signal, wherein the at least one switch is controlled to switch according to the PWM signal and according to a zero current signal related to a current of the output power;
• and
• generating a time adjustment signal according to a first clock signal related to the PWM signal, wherein when the switching converter operates in a discontinuous conduction mode (DCM) and a switching frequency of the PWM signal is lower than a predetermined frequency threshold, the time adjustment signal is configured to operably adjust the ON-time or OFF-time in a random or a pseudo-random fashion;
• wherein when the switching converter operates in a continuous conduction mode (CCM), the switching frequency is kept as a constant.