| Patent application number | Description | Published |
|---|
| 20090230873 | DRIVING CIRCUIT FOR LIGHT EMITTING DIODES - A driving circuit includes a DC-to-DC voltage converter, a current source, a detector and a feedback control circuit. The DC-to-DC voltage converter has a switch and generates a driving voltage on first ends of the series of light emitting diodes, in which a magnitude of the driving voltage is correlated with conduction of the switch. The current source is coupled to second ends of the series of the light emitting diodes and provides driving currents flowing through the light emitting diodes. The detector generates a feedback voltage corresponding to a sum of voltages on the second ends of the series of the light emitting diodes. The feedback control circuit generates a first control signal which controls the conduction of the switch in response to the feedback voltage. | 09-17-2009 |
| 20100072973 | Voltage Converter - A voltage converter to convert a high voltage to a low voltage is provided. The voltage converter comprises: a current mirror, a current bias, a plurality of loads and a low voltage output. The current mirror comprises a first PMOS and a second PMOS, wherein the source of the first PMOS and the second PMOS receive a high voltage input which is a supply voltage of the current mirror, and the gate of the first PMOS is connected to the drain of the first PMOS. The current bias is connected between the drain of the first PMOS and a ground potential. The plurality of loads are parallel connected between the drain of the second PMOS and the ground potential. And the low voltage output connected to the drain of the second PMOS. | 03-25-2010 |
| 20100085074 | POWER CONVERTER, SHORT DETECTION CIRCUIT THEREOF, AND METHOD FOR DETECTING SHORT - A short detection circuit, for detecting an output node corresponding to an output voltage converted from an input voltage of a power converter, includes a first current source, a charging/discharging unit, a comparator, and a logic control unit. The charging/discharging unit performs charging operation in accordance with the first current source to generate a charging signal in a shorted condition of the output node. The comparator outputs an enable signal by comparing the charging signal with a reference signal. The logic control unit is controlled by the enable signal to generate a fault signal for turning off a first switch coupled between the output node and the input voltage in the shorted condition of the output node. A method for detecting short of an output node corresponding to an output voltage converted from an input voltage of a power converter is also disclosed herein | 04-08-2010 |
| 20100156320 | LED CIRCUIT WITH HIGH DIMMING FREQUENCY - A LED circuit comprises: an inductor, a group of LEDs, a capacitor, a power MOS and a switching circuit. The inductor is connected to a voltage supply and a first node; the group of LEDs is connected to the first node and a ground potential; the capacitor is connected to the first node and a ground potential; the power MOS is connected to the first node and a ground potential, wherein the gate of the power MOS receives a switching signal such that the capacitor is charged when the power MOS is turn on to further turn on the LEDs and the capacitor is discharged when the power MOS is turn off to turn off the LEDs. The switching circuit is to generate the switching signal. | 06-24-2010 |
| 20100214001 | Level Shift Circuit - A level shift circuit includes an inverter, a shifting circuit, a first transistor, and a second transistor. The inverter inverts an original input signal into an inverted input signal. The shifting circuit generates a control signal according to the original input signal, the inverted input signal, and a reference voltage. The first transistor has a gate, a source, and a drain, in which the gate of the first transistor receives the control signal, and the source of the first transistor is connected to a high supply voltage. The second transistor has a gate, a source, and a drain, in which the gate of the second transistor receives the inverted input signal, the drain of the second transistor is connected to the drain of the first transistor, and the source of the second transistor is connected to a ground terminal or a low supply voltage. | 08-26-2010 |
| 20100254506 | Counter and Frequency Divider Thereof - A frequency divider includes a transmission gate, a first inverter, a first switch circuit, a second switch circuit, and a second inverter. The transmission gate transmits a clock signal according to an inverted enable signal. The first inverter inverts the clock signal outputted from the transmission gate. The first switch circuit generates a first control signal according to the inverted clock signal and an output signal of the frequency divider. The second switch circuit generates a second control signal according to the clock signal, the inverted clock signal, and the first control signal. The second inverter inverts the second control signal to generate the output signal. The frequency of the clock signal is a multiple of the frequency of the output signal. | 10-07-2010 |
| 20100283409 | LED Driver and Start-Up Feedback Circuit Therein - An LED driver includes a start-up feedback circuit, an operating feedback circuit and a multiplexer. The start-up feedback circuit has first terminals for receiving LED feedback voltages each delivered from at least one LED coupled to an output terminal for outputting an output voltage, of the LED driver, and generates a start-up feedback voltage accordingly. The operating feedback circuit has second terminals for receiving the LED feedback voltages, and generates an operating feedback voltage accordingly. The multiplexer selects the start-up feedback voltage for initial boost of the output voltage when the LED driver is initially activated, and selects the operating feedback voltage for following boost of the output voltage when the output voltage increases to a certain value. | 11-11-2010 |
| 20110285304 | Error Amplifier and LED Circuit Comprising the Same - An error amplifier and a LED circuit comprising the same are provided. The LED circuit comprises an inductor, a group of LEDs and a power MOS connected to the inductor, an error amplifier and a pulse width modulator controlling the gate of the power MOS according to an error amplifier output. The error amplifier comprises a differential input stage, an output stage having a first NMOS, a first PMOS, a second NMOS, a second PMOS and a control switch module. During a first operation mode, the control switch module connects the first NMOS and PMOS and connects the second NMOS and PMOS, and during a second operation mode, control switch module disables the second NMOS and PMOS. | 11-24-2011 |
| 20110285316 | Error Amplifier and LED Circuit Comprising the Same - An error amplifier and a LED circuit comprising the same are provided. The LED circuit comprises an inductor, a group of LEDs and a power MOS connected to the inductor, an error amplifier and a pulse width modulator controlling the gate of the power MOS according to an error amplifier output. The error amplifier comprises a differential input stage, an output stage having a NMOS, a PMOS and an adjusting current source connected to the gate of the PMOS. During a first operation mode, a control voltage makes the adjusting current source turn on, and during a second operation mode, the control voltage makes the adjusting current source turn off. | 11-24-2011 |
