US 12,483,112 B2
Controller and controlling method for quasi-resonant controlled switching converter
Xuefeng Chen, Hangzhou (CN)
Assigned to Monolithic Power Systems, Inc., Kirkland, WA (US)
Filed by Monolithic Power Systems, Inc., Kirkland, WA (US)
Filed on Oct. 19, 2023, as Appl. No. 18/489,923.
Prior Publication US 2024/0171058 A1, May 23, 2024
Int. Cl. H02M 3/335 (2006.01); H02M 1/00 (2006.01)
CPC H02M 1/0058 (2021.05) [H02M 1/0009 (2021.05); H02M 3/33507 (2013.01)] 20 Claims
OG exemplary drawing
 
1. A controller for a quasi-resonant controlled switching converter, wherein the quasi-resonant controlled switching converter has an energy storage component and a power switch that is coupled to the energy storage component, and the controller comprising:
a sample-and-hold circuit coupled to a detection circuit to receive a voltage detection signal that represents a voltage across the power switch, wherein the sample-and-hold circuit is configured to provide a plateau voltage when a sample-and-hold signal is enabled, and the plateau voltage represents a maximum value of the voltage detection signal;
a first voltage-dividing circuit coupled to the sample-and-hold circuit to receive the plateau voltage and configured to provide a first divided voltage based on the plateau voltage;
a timing circuit configured to provide a time detection signal at its output terminal, wherein the timing circuit is configured to start timing at a first time point when the voltage detection signal is lowered to the first divided voltage and to end timing at a second time point when the voltage detection signal is lowered to a zero-crossing threshold voltage, and a time duration between the first time point and the second time point is equal to a pulse width of the time detection signal;
a first converting unit configured to provide a control voltage in response to the time detection signal, wherein the control voltage is proportional to the time duration;
an enable circuit configured to provide an enable signal that corresponds to a target valley number for a valley switching of the power switch;
a second converting unit configured to receive the enable signal and the control voltage and provide a delayed enable signal, wherein the delayed enable signal has a first time delay relative to the enable signal, and the first time delay is proportional to the control voltage; and
a logic circuit configured to receive the delayed enable signal and turn on the power switch based on the delayed enable signal.