Silergy Semiconductor Technology (Hangzhou) Ltd

Guojia Liu

Jian Deng

Xiaoru Xu

Wei P Chen

Jianxin Wang

A method of controlling a dimmable LED driving circuit, can include: detecting a voltage across an electrolytic capacitor in the LED driving circuit; determining whether the voltage across the electrolytic capacitor is less than a predetermined value; and charging the electrolytic capacitor by an auxiliary circuit when the voltage across the electrolytic capacitor is less than the predetermined value, in order to reduce time required for the voltage across the electrolytic capacitor to rise to a start-up voltage of an LED load.

Integrated circuit, dimmable light-emitting diode driving circuit and driving method

In one embodiment, a zero-crossing detection circuit can include: (i) a first detection circuit configured to detect a current through a main transistor of a main circuit of a switching power supply, and to generate a voltage sense signal that represents the current through the main transistor; (ii) a second detection circuit configured to detect if quasi-resonance occurs in the main circuit, the second detection circuit being configured to generate at least one pulse signal when the quasi-resonance is detected; and (iii) a control circuit configured to receive the at least one pulse signal and the voltage sense signal, to turn the main transistor off when the current through the main transistor reaches a predetermined value, and to turn the main transistor on when the at least one pulse signal is active.

Zero-crossing detection circuit

In one embodiment, a current feedback circuit can include: (i) a first current mirror circuit having an input terminal coupled to a source of a main power transistor of a switching power supply, and a control terminal configured to receive a PWM control signal, the first current mirror circuit being configured to generate a first mirror current; (ii) the first current mirror circuit and the main power transistor being on such that an output sampling current flows through the first current mirror circuit and the main power transistor when the PWM control signal is active; and (iii) a second current mirror circuit configured to generate an output feedback current that is in a predetermined direct proportion with the output sampling current, and is generated in accordance with the first mirror current.

Current feedback method, current feedback circuit, driving circuit and switching power supply thereof

A source driver circuit can include: (i) a control transistor having a control terminal and first and second power terminals, where the control transistor is coupled between a power terminal of a main switching transistor and ground; (ii) a power supply capacitor coupled between the control terminal of the main switching transistor and ground, where the power supply capacitor is configured to receive a bias voltage that is substantially constant; (iii) a freewheeling diode having a cathode coupled to a control terminal of the main switching transistor, and an anode coupled to the second power terminal of the main switching transistor; and (iv) the control transistor being controllable to be periodically turned on and off to control the main switching transistor to correspondingly follow on and off states of the control transistor.

Source driver circuit and control method thereof

Disclosed are compensation circuits for a switching power supply. In one embodiment, a compensation circuit can include: (i) a transconductance amplifier configured to receive a reference signal and a feedback signal, and to generate an amplifier output signal according to a difference between the reference signal and the feedback signal; (ii) a switching circuit configured to receive the amplifier output signal, where the switching circuit is controllable by a control signal from a switch control circuit; and (iii) a charging circuit coupled to the switching circuit, where the charging circuit is configured to be charged by the amplifier output signal in response to the control signal, and to generate a compensation signal therefrom.

Compensation circuit and switching power supply thereof

In one embodiment, a source driving circuit configured for a switching power circuit, can include: (i) a source transistor coupled between a source of a main power transistor and ground, where the source transistor can be controlled by a PWM control signal; (ii) the main power transistor being on when the source transistor is on and a gate-source voltage of the main power transistor exceeds a conduction threshold voltage; (iii) a source diode having an anode coupled to the main power transistor source, and a cathode coupled to a delay circuit and a power supply capacitor; and (iv) the delay circuit controlling the main power transistor to turn off a delay time after the source transistor is turned off, where the delay time allows charging of the power supply capacitor such that a voltage across the power supply capacitor is at least a level of a reference voltage.

Growing community of inventors

Hangzhou, China

Guojia Liu