Himax Analogic, Inc.

Kuan-Jen Tseng

Ching-Wei Hsueh

Po-Yu Li

Kuo-Hung Wu

A charge module is configured to pre-charge a control node to a pre-charged voltage, such that in a case a control module outputs a control voltage, a drive module is activated according to a gate voltage summed by the control voltage and the pre-charged voltage. The charge module includes a first switch, a charge switch, and a second switch. The first switch is configured to provide a first voltage to an operation node. The charge switch is configured to be switched on corresponding to the first voltage of the operation node, so as to charge the control node. The second switch is configured to provide a second voltage to the operation node according to the gate voltage.

Charge module, driving circuit, and operating method

An error amplifier and a driving circuit are disclosed herein. The error amplifier is configured to charge a compensation capacitor with an error current. The error amplifier includes an input stage, a main output stage, and an auxiliary output stage. The input stage is configured to provide a first differential output signal and a second differential output signal in response to a comparison between a reference voltage and a feedback voltage. The main output stage is configured to charge the compensation capacitor. The auxiliary output stage is configured to be activated to charge the compensation capacitor. a first operation, both the main output stage and the auxiliary output stage charge the compensation capacitor. In a second operation, the main output stage charges the compensation capacitor, and the auxiliary output stage is deactivated and does not charge the compensation capacitor.

Driving circuit and error amplifier thereof

A light emitting diode driving circuit includes connected driving units, each of which is configured for driving multiple channels of light emitting diodes generating a feedback voltage for the corresponding driving unit. Each of the driving units includes a selection circuit for comparing the feedback voltage with an input voltage to output a smaller one of the feedback voltage and the input voltage to a next one of the driving units, as the input voltage for the next one of the driving units.

Light emitting diode driving circuit

A voltage converting circuit for converting an input voltage into an output voltage is disclosed. The voltage converting circuit includes a modulation signal generator, a comparator and a logic unit. The modulation signal generator is configured for generating a pulse width modulation (PWM) signal responsive to a feedback signal corresponding to the output voltage and a load coupled thereto. The comparator is configured for comparing the feedback signal with a reference signal to output a comparing signal. The logic unit is configured for performing a logical conjunction of the PWM signal and the comparing signal to generate a control signal for adjusting an input current corresponding to the input voltage to regulate the output voltage. A method for converting an input voltage into an output voltage is also disclosed herein.

Voltage converting circuit and method

A current regulating circuit includes a transistor and an operational amplifier. The transistor receives a load current and generates a feedback voltage corresponding to the load current. The operational amplifier receives a reference voltage and the feedback voltage to control the transistor. The operational amplifier further includes an input stage and an output stage. The input stage includes amplifier inputs each for alternately receiving the reference voltage and the feedback voltage so that the input stage generates operating voltages corresponding to the reference voltage and the feedback voltage. The output stage receives the operating voltages alternately to control the transistor. A driver and a method of current regulation are also disclosed herein.

Driver, current regulating circuit thereof, and method of current regulation, with alternating voltages therein

A channel detection device includes a disable circuit, LED pins, receivers and an error detection circuit. The disable circuit sends a disabling pulse to one or some LED pins of the plurality of LED pins, where the one or some LED pins are connected to the disable circuit. Each of the receivers is connected to one of the plurality of LED pins respectively and is capable of outputting an inhibiting signal when the LED pin connected receives the disabling pulse from the disable circuit. The error detection circuit is coupled to the receivers and the LED pins. The error detection circuit is configured to detect open-circuit of some LED pins of the plurality of LED pins, and bypass the detection of open-circuit of some other LED pin of which the receiver outputs the inhibiting signal.

Channel detection device

A voltage selection circuit selecting a minimum voltage from the remainder voltages outputted from the light emitting diode channels is disclosed. The voltage selection circuit includes a first picking circuit, which has the first operation amplifiers, a positive input terminal, an output terminal, a negative input terminal, and an output stage. Each of the first operation amplifiers includes a positive input terminal, an output terminal, a negative input terminal, and an output stage. The positive input terminal receives one of the remainder voltages from one of the first ends of the light emitting diode channels. The output terminal outputs the minimum voltage, in which the output terminals of the first operation amplifiers are connected together. The negative input terminal is electrically connected to the output terminal. The output stage is electrically connected to the output terminal, in which the output stage has current sinking ability stronger than current sourcing ability.

Light emitting diode circuit, light emitting diode driving circuit, voltage selection circuit, and method for driving thereof

An LED driving circuit includes a control logic circuit, a dimming circuit and a counter. The control logic circuit is electrically coupled to an enable pin for receiving an input signal, and asserts an internal enable signal for activating the LED driving circuit. The dimming circuit is electrically coupled to the enable pin and outputs a control signal for controlling current flowing into at least one load connected to the LED driving circuit. The counter identifies the input signal based on a clock signal and asserts a detection signal for informing the control logic circuit of de-asserting the internal enable signal to de-activate the LED driving circuit when identifying the input signal as the enable signal being de-asserted for a predetermined period of the clock signal. A method of controlling an LED driving circuit is also disclosed herein.

LED driving circuit and method of controlling the same

An over-current protection circuit includes a voltage generating unit and a comparing unit. The voltage generating unit is configured for receiving a first voltage and generating a reference voltage. The reference voltage has an offset positively dependent on temperature and negatively dependent on the first voltage, and the offset of the reference voltage varies along with another offset varying within a sense voltage sensed by the over-current protection circuit. The comparing unit is configured for comparing the reference voltage with the sense voltage to output a control signal for de-asserting the sense voltage when the sense voltage is correlated to an over-current condition of the sense voltage exceeding the reference voltage. A driver is also disclosed herein.

Driver and over-current protection circuit therein

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.

Switching circuit adapted in LED circuit

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.

LED circuit

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.

Audio power amplifier and a pre-amplifier thereof

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.

Oscillator

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.

Voltage trimming circuit

An operational amplifier includes an output unit, a voltage drop element and a feedback unit. The output unit is provided for sourcing an output current to an output of the operational amplifier when operating with a power unit for providing a current being multiple times the value of the output current. The voltage drop is provided for generating a voltage drop in accordance with the output current. The feedback unit is controlled with the voltage drop generated by the voltage drop element and controls the output unit and the power unit to regulate the output current in accordance with the voltage drop.

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Sinshih, Taiwan

Kuan-Jen Tseng