Richtek Technology Corporation

Richtek Technology Corporation, R.o.c

Roland Van Roy

Jing-Meng Liu

Leng-Nien Hsiu

Chia-Wei Liao

Pei-Yuan Chen

Pei-Cheng Huang

A power-factor-improving circuit and method for an offline converter block the DC component and obtain the AC component of an input voltage of the offline converter. The AC component is superpositioned onto a DC bias signal to generate a dimming signal for the offline converter to adjust an output current of the offline converter. The offline converter has a high power factor due to the dimming signal with the AC component of the input voltage. In addition, the average of the dimming signal is determined by the DC bias signal, hence the output current can be precisely controlled according to the DC bias signal.

Power-factor-improving circuit and method for an offline converter

The present invention discloses a switching regulator and a control circuit and a control method thereof. The switching regulator generates a compensation signal according to a feedback signal, and generates a driving signal according to the compensation signal, to control a power stage for converting an input voltage to an output voltage. The compensation signal is adjusted according to the input voltage, such that when the input voltage is equal to or lower than a predetermined level, the compensation signal is kept at a predetermined value.

Switching regulator and control circuit and control method thereof

The present invention discloses an active bleeder circuit capable of triggering a tri-electrode AC switch (TRIAC) circuit in all phase. The active bleeder circuit receives a rectified signal having an OFF phase and an ON phase. The active bleeder includes: a detection circuit for generating a detection signal according to the rectified signal and accumulating the detection signal in the OFF phase of the rectified signal; and a current sinker circuit coupled to the detection circuit, for generates a latching current to trigger the TRIAC circuit by operating a switch when the detection signal exceeds a predetermined level. The present invention also discloses a light emitting device power supply circuit and a TRIAC control method using the active bleeder circuit.

Active bleeder circuit triggering TRIAC in all phase and light emitting device power supply circuit and TRIAC control method using the active bleeder circuit

The present invention discloses a circuit and a method for providing absolute information for floating grounded integrated circuit. The method includes: receiving an absolute information sense signal carrying absolute information; converting the absolute information sense signal to a current signal; and generating an internal reference signal according to the current signal, wherein the internal reference signal or a relationship between the internal reference signal and a floating ground level is related to the absolute information.

Circuit and method for providing absolute information for floating grounded integrated circuit

The present invention discloses a light emitting device driver circuit and a method for driving a light emitting device. In the present invention, the secondary windings of a transformer provide positive and negative secondary voltages, so as to generate positive and negative output voltages. A light emitting device circuit is coupled between the positive and negative output voltages. As such, the specification to withstand high voltage for a device in the circuit is reduced.

Light emitting device driver circuit driving light emitting device by positive and negative voltages and method for driving light emitting device by positive and negative voltages

The present invention discloses an LED driver with direct AC-DC conversion and control function, and a method and integrated circuit therefor. The LED driver comprises: a primary side circuit receiving rectified AC power, the primary side circuit including at least one power switch; a transformer coupled to the primary side circuit and controlled by the at least one power switch to convert a primary voltage to a secondary voltage which is supplied to an LED circuit; and a secondary side circuit coupled to the transformer, the secondary side circuit directly controlling current flowing through the LED circuit and sending a feedback signal to the primary side circuit to control the at least one power switch thereby.

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Eindhoven, Netherlands

Roland Van Roy