Patent ID: 9577515
Date: 2017-02-21
CPC Classifications: H02M,Y02B

Claim:
1. A controller for generating jitters in a quasi resonant mode, the controller comprising: a feedback pin for receiving a feedback voltage from a secondary side of a power converter; a voltage generation unit for generating a first voltage according to the feedback voltage and a pulse, wherein the voltage generation unit comprises: a switch for being turned on according to the pulse, wherein when the switch is turned on, the first voltage is pulled down to ground; a variable current source for periodically increasing a charging current of the variable current source with time after decreasing the charging current of the variable current source with time, or periodically decreasing the charging current of the variable current source with time after increasing the charging current of the variable current source according to the feedback voltage and a digital signal; and a capacitor coupled between the variable current source and the ground for generating the first voltage according to the charging current when the switch is turned off; a pulse generator for generating the pulse when a control signal controlling a power switch of a primary side of the power converter is enabled; and a comparator for controlling enabling and disabling of a switching signal according to the first voltage and a variable reference voltage, wherein the variable reference voltage is periodically decreased with time after being increased with time, or periodically increased with time after being decreased with time within a predetermined voltage range according to the digital signal.