Abstract: A LED circuit is provided. The LED circuit comprises: a plurality of LED channels, a driving module and a feedback-selecting module. The driving module supplies a driving voltage to the plurality of LED channels according to a feedback voltage. The feedback-selecting module comprises an open detection unit and a minimum-selecting unit. The open detection unit performs an open detection mechanism to separate the plurality of LED channels into a plurality of open LED channels and a plurality of non-open LED channels having an output voltage respectively. The minimum-selecting unit performs a selection mechanism to select a minimum output voltage as the feedback voltage from the output voltage of each of the plurality of non-open LED channels. A LED circuit operation method adapted in the LED circuit is provided herein as well.

Abstract: 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.

Abstract: 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.

Abstract: A current sense circuit includes a power transistor, a first level shifter, an operational transconductance amplifier (OTA), a second level shifter, and a dummy transistor. The power transistor has a first terminal and a power control terminal coupled to a control voltage. The first level shifter is coupled to the first terminal and pulls up a voltage of the first terminal to an operating voltage. The OTA is coupled to the first level shifter and converts the operating voltage into an operating current. The second level shifter is coupled to the OTA and pulls down the operating voltage to the voltage of the first terminal. The dummy transistor has a dummy control terminal with the control voltage, and a third terminal coupled to the second level shifter and having the same voltage as the voltage of the first terminal.

Abstract: 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.

Abstract: A circuit and a method for driving light emitting diodes (LEDs) are provided. First, an input voltage is converted into an output voltage and the output voltage is transmitted to the anode terminals of LED strings. The output voltage is reduced when the output voltage is greater than a first threshold voltage and the output voltage is reduced when the lowest level among the cathode terminal voltages of all the LED strings is greater than a second threshold voltage. Thus, the output voltage can be maintained at a lower level for driving all the LED strings to reduce unnecessary power wastage.

Abstract: A soft-start circuit is provided. The soft-start circuit comprises: an input stage, a pump stage, a second resistor and a capacitor. The input stage comprises a first resistor to receive an input voltage to provide a reference current at a first node. The pump stage comprises N current branches connected in parallel each comprising a current source connected to the first node and a switch to transfer the current from the current source to the second node while the switch operates in a connecting state. The switches has 2N connecting modes performed one after another to generate an output current with a gradual increment output current at the second node with 2N current levels; and the second resistor and the capacitor are connected in parallel between the second node and the ground potential to generate an output voltage with a gradual increment with 2N voltage levels according to output current.

Abstract: A trimming circuit is provided. The trimming circuit had at least a trimming cell, and each of the at least trimming cell includes three current paths and a fuse. A first one of the current paths is interrupted when a second one of the current paths is uninterrupted, and the first one of the current paths is uninterrupted when the second one of the current paths is interrupted. When a trimming control signal is at an enable state, a third one of the current paths is uninterrupted, such that the fuse is blown. Based on the status of the fuse, the trimming circuit is capable of trimming an output voltage or an output current of an electric apparatus.

Abstract: A LED circuit is provided. The LED circuit comprises: an inductor, a group of LEDs, a power MOS and a switching circuit. The switching circuit comprises: an error amplifier generating an error output, a PWM, a RC circuit and a control means. The PWM generates a switching signal according to the error output to control the power MOS to charge or discharge the group of LEDs; the RC circuit comprises at least one first capacitor each comprising a switch, at least one second capacitors; and a resistive means connected in series between the first and the second capacitors and the error output. The control means generates a control signal according to the dimming signal to turn on the switches to activate the first capacitors during the active period of the dimming signal and turn off the switches to deactivate the first capacitors during the inactive period of the dimming signal.

Abstract: 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.

Abstract: A driving circuit for a light emitting diode (LED) and a method thereof are provided. The driving circuit includes a voltage converting circuit and a reference voltage generator. The reference voltage generator generates a reference voltage according to the cathode voltage of the LED. The voltage converting circuit automatically adjusts the driving voltage of the LED based on the reference voltage so as to reduce the possibility of unnecessary power wastage caused by high driving voltage.

Abstract: A charge pump driving circuit for generating a driving pulse signal to drive a charge pump circuit is disclosed. The charge pump driving circuit includes a control signal generator and a driving signal generator. The control signal generator generates a first control signal, a second control signal, and a third control signal, in which the third control signal transits in the first place, the first control signal transits next, and the second control signal transits last. The driving signal generator, controlled by the first control signal, the second control signal and the third control signal, generates the driving pulse signal, in which the driving signal generator has a rare short circuit current flowing from a supply terminal providing a supply voltage to a ground terminal providing a ground voltage.

Abstract: A power-off control circuit adapted in a LCD panel comprising a gate pulse modulator and a level shifter is provided. The power-off control circuit comprises a logic gate and a control switch. The logic gate comprises a first input to receive an internal power supply, a second input to receive a power state signal and a logic output to generate a control signal. When the power supply is on, the internal power supply is on and the power state signal is in a first state to make the control signal turn off the control switch. When the power supply is off, the internal power supply is on and the power state signal is in a second state to make the control signal turn on the control switch to make the gate pulse modulator makes pixels of a pixel array to perform a discharge activity.

Abstract: 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.

Abstract: 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.

Abstract: An audio power amplifier includes a pre-amplifier, an error amplifier, a comparator, a bridge circuit, and a feedback circuit, in which the gain of the pre-amplifier gradually increases when the audio power amplifier is powered on. The comparator generates a PWM signal by comparing a reference signal and an amplified audio signal. The bridge circuit has switches controlled according to the PWM signal such that a driving current alternately flows to and from a load. The feedback circuit generates the feedback signal indicating a condition of the load.

Abstract: An oscillator is provided. The oscillator comprises a flip-flop module, a first and a second setting module. The first setting module comprises: a first switch device to generates a first switch signal according to a first oscillating signal, an NMOS and an inverter. The NMOS comprises a drain to receive a first charging current and a gate to receive the first switch signal, wherein the drain is charged or discharged according to the first switch signal. The inverter is connected to the drain to generate a first setting signal. The second setting module comprises a second switch device to generate a second switch signal according to a second oscillating signal and a comparator to generate a second setting signal according to the second switch signal and a reference voltage. The flip-flop module generates the first and the second oscillating signal according to the first and the second setting signal.

Abstract: An oscillator is provided. The oscillator comprises a flip-flop module, a first and a second setting module. The first setting module comprises: a first switch device to generates a first switch signal according to a first oscillating signal, an NMOS and an inverter. The NMOS comprises a drain to receive a first charging current and a gate to receive the first switch signal, wherein the drain is charged or discharged according to the first switch signal. The inverter is connected to the drain to generate a first setting signal. The second setting module comprises a second switch device to generate a second switch signal according to a second oscillating signal and a comparator to generate a second setting signal according to the second switch signal and a reference voltage. The flip-flop module generates the first and the second oscillating signal according to the first and the second setting signal.

Abstract: A switching circuit adapted in an LED circuit and an LED circuit are provided. The switching circuit has a mode-selecting circuit, a comparator and a control module. The mode-selecting circuit has a voltage-dividing module and a switch. The voltage-dividing module receives and divides a reference voltage to further generate a working voltage. The switch is connected to the voltage-dividing module, wherein the switch has an output. The comparator comprises a first input connected to the switch, a second input and a comparator output. During a measuring mode, the switch transfers the reference voltage and the second input is connected to the comparator output. During a working mode, the switch transfers the working voltage, the second input of the comparator receives an output voltage of the LED circuit and the control module generates a control signal according to the voltage of the comparator output to switch the LED circuit.

Abstract: A voltage trimming circuit is provided. The voltage trimming circuit has an input stage, an up-trimming resistor ladder, a down-trimming resistor ladder and a control means. The input stage has a first input, a second input and an output, wherein the first output is to receive an input voltage, the second input is connected to a connection point and the output is to provide an output voltage based on a difference between the voltage of the first and the second input. The up-trimming resistor ladder is connected between the output of the input stage and the connection point and the down-trimming resistor ladder connected between a ground potential and the connection point. The control means controls the resistance of the up-trimming and the down-trimming resistor ladder to up-trim or down-trim the output voltage.