Controller for eliminating acoustic noise of a power converter and related method thereof

摘要

A controller for eliminating acoustic noise of a power converter includes a control unit and a gate signal generation unit. The control unit is used for detecting a frequency corresponding to a gate control signal in a burst mode of the power converter. When the frequency is greater than a predetermined frequency, the control unit increases a resistance of a compensation resistor coupled to a compensation pin of the power converter; and when the frequency is less than the predetermined frequency, the control unit decreases the resistance of the compensation resistor. The gate signal generation unit is coupled to the control unit for generating the gate control signal to a power switch of a primary side of the power converter according to the resistance of the compensation resistor. The power switch is turned on according to the gate control signal.

主权项

1. A controller for eliminating acoustic noise of a power converter, the controller comprising:
a feedback pin for receiving a feedback voltage from a secondary side of the power converter, wherein the feedback voltage corresponds to an output voltage of the secondary side of the power converter; a current detection pin for generating a detection voltage according to a current flowing through a primary side of the power converter and a resistor; a burst mode signal generation module coupled to the feedback pin for generating a burst mode signal according to a first reference voltage and the feedback voltage, or according to a second reference voltage and the feedback voltage, wherein the burst mode signal generation module comprises:
a first comparator for generating the burst mode signal according to the first reference voltage and the feedback voltage;a second comparator for generating the burst mode signal according to the second reference voltage and the feedback voltage; anda control unit coupled to the gate signal generation unit for detecting a frequency corresponding to the gate control signal, wherein when the frequency is greater than a predetermined frequency, the control unit controls the first comparator to generate the burst mode signal according to the first reference voltage and the feedback voltage, when the frequency is less than the predetermined frequency, the control unit controls the second comparator to generate the burst mode signal according to the second reference voltage and the feedback voltage, and the second reference voltage is greater than the first reference voltage; a gate signal generation unit coupled to the burst mode signal generation module for generating a gate control signal corresponding to a burst mode of the power converter to a power switch of the primary side of the power converter according to the burst mode signal, wherein the power switch is turned on according to the gate control signal; and a turning-on time generation unit coupled to the burst mode signal generation module, the current detection pin, and the gate signal generation unit for determining a turning-on time of the power converter in the burst mode of the power converter according to the first reference voltage and the detection voltage, or according to the second reference voltage and the detection voltage.