Chengdu Monolithic Power Systems Co., Ltd.

Hangzhou Mps Semiconductor Technology Ltd.

Monolithic Power Systems, Inc.

Xuefeng Chen

Hui Li

Xia Zhou

A controller used in an isolated switching converter having a transformer, a primary switch and a secondary switch. The controller has an ON-time control circuit. The secondary switch is turned on for a second ON-time after a current flowing through the secondary switch decreases to zero. The ON-time control circuit provides an ON-time control signal to control the second ON-time of the secondary switch based on a drain terminal voltage of the secondary switch, the output voltage of the isolated switching converter and a resistance of an external resistor outside of the controller.

Isolated switching converter with soft switching and control method thereof

A controller for a quasi-resonant controlled switching converter includes a sample-and-hold circuit for providing a plateau voltage based on a voltage detection signal that represents a voltage across a power switch, a first voltage-dividing circuit for providing a first divided voltage based on the plateau voltage, a timing circuit, a first converting unit, an enable circuit for providing an enable signal corresponding to a target valley number for a valley switching of the power switch, and a logic circuit. The timing circuit starts timing when the voltage detection signal is lowered to the first divided voltage and ends timing when the voltage detection signal is lowered to a zero-crossing threshold voltage. The first converting unit provides a control voltage corresponding to the time duration of the timing circuit. The logic circuit turns on the power switch based on the control voltage and the enable signal.

Controller and controlling method for quasi-resonant controlled switching converter

A controller used in a switching power supply having a power switch and an energy storage element. A winding voltage of the energy storage element oscillates to provide an oscillation signal having one or more valleys during an OFF period of the power switch. The controller has a target valley number generator for providing a target locked valley number which is not exceeding an upper limit, a first comparison circuit for providing a first square wave signal by comparing a voltage sensing signal representative of the oscillation signal with a first threshold voltage, a second comparison circuit for providing a second square wave signal by comparing the voltage sensing signal with a second threshold voltage less than the first threshold voltage, and an upper limit updating circuit to determine if to update the upper limit.

Quasi-resonant controlled switching power supply with an adaptive upper limit of valley number

A controller used in an isolated switching converter with a transformer, a primary switch and a secondary switch, the controller has a maximum sense circuit for providing a first voltage signal representative of a maximum value of a first voltage across the secondary switch, and a timer for starting timing when the first voltage increases to a second voltage signal less than the first voltage signal and stop timing when the first voltage increases to the first voltage signal, and the timing duration of the timer is a first time interval. The secondary switch is turned on for a second ON-time after a current flowing through the secondary switch decreases to zero. The second ON-time of the secondary switch is adjusted so that the first time interval of the next switching cycle is close to a first time threshold.

A controller used in an isolated switching converter. The controller has an error amplifying circuit for generating a first compensation signal based on the difference between an output feedback signal and a reference voltage, a control generator for generating a first and second control signals based on the first compensation signal, an isolation circuit for providing a first synchronous signal electrically isolated from the first control signal and a second synchronous signal electrically isolated from the second control signal, an upper threshold generator for providing an upper threshold voltage, and a peak current generator for providing a peak current signal for controlling a peak value of a current flowing through the primary switch based on the first synchronous signal, the second synchronous signal and the upper threshold voltage. The upper threshold voltage is adjusted above a first upper threshold voltage when a peak power demand is made.

Isolated switching converter for peak power demand and control method thereof

A controller used in an isolated switching converter having a transformer, a primary switch and a secondary switch. The controller has an error amplifying circuit, a control generator and an isolation circuit. The error amplifying circuit generates a first compensation signal based on the difference between a reference voltage and an output feedback signal. The control generator generates a first and second control signals based on the first compensation signal. The isolation circuit has a first channel for providing a first synchronous signal electrically isolated from the first control signal, for controlling a peak value of a current flowing through the primary switch, and has a second channel for providing a second synchronous signal electrically isolated from the second control signal, for controlling the switching frequency of the primary switch.

Isolated switching converter with two isolated channels and control method thereof

A controller of a switching converter having a switch and an energy storage component. The controller has a hysteresis feedback circuit for generating a hysteresis feedback signal based on an output feedback signal of the switching converter, a first comparison circuit for generating a first comparison signal by comparing the hysteresis feedback signal with a ramp signal, a second comparison circuit for generating a second comparison signal by comparing the output feedback signal with the ramp signal, and a turn-on control circuit. The turn-on control circuit generates a target locked valley number based on a valley pulse signal in response to one or more valleys of a voltage drop across the switch, the first comparison signal, the second comparison signal and a current locked valley number, and further generates a turning on control signal corresponding to the target locked valley number for turning ON the switch.

Switching converter with quasi-resonant control and control method thereof

A control method of a zero-voltage switching converter with quasi-resonant control, the converter has a first switch and second switch respectively coupled to a primary winding and an auxiliary winding. The control method is: generating a hysteresis feedback signal based on an output feedback signal indicative of an output signal of the converter; comparing the hysteresis feedback signal with a ramp signal and generating a first comparison signal; comparing the output feedback signal with the ramp signal and generating a second comparison signal; generating a target locked valley number based on a valley pulse signal indicative of valleys of a voltage drop across the second switch, the first and second comparison signals; generating a turning on control signal corresponding to the target locked valley number for the second switch; and providing a control signal to turn on the first switch after turning off the second switch.

Converters and control methods of zero-voltage switching and quasi-resonant switching

A power supply circuit for a switching mode power supply, having: a charging capacitor coupled to an auxiliary winding; a power supply diode coupled to a power supply capacitor, wherein the charging capacitor has a connecting terminal coupled to the power supply diode, and the charging capacitor and the power supply diode are serially coupled between the auxiliary winding of the switching mode power supply and the power supply capacitor; and a power supply switch coupled between the connecting terminal and a primary ground of the switching mode power supply.

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Hangzhou, China

Xuefeng Chen