HIMAX ANALOGIC, INC. Patent applications |
Patent application number | Title | Published |
20150115361 | Lateral Diffused Metal Oxide Semiconductor - A lateral diffused N-type metal oxide semiconductor device includes a semiconductor substrate, an epi-layer on the semiconductor substrate, a patterned isolation layer on the epi-layer, a N-type double diffused drain (NDDD) region in a first active region of the patterned isolation layer, a N+ heavily doped drain region disposed in the NDDD region, a P-body diffused region disposed in a second active region of the patterned isolation layer, a neighboring pair of a N+ heavily doped source region and a P+ heavily doped source region disposed in the P-body diffused region, a first gate structure disposed above a channel region of the patterned isolation layer and a second gate structure disposed above the second active region. The second gate structure and the first gate structure are spaced at a predetermined distance. | 04-30-2015 |
20150085414 | Output Stage with Short-Circuit Protection - An output stage with short-circuit protection includes a power transistor, a detecting module, a disable module, and a driving module. The power transistor is electrically connected between a voltage source and an output node. A gate end of the power transistor is configured to receive a driving signal. The detecting module is configured to detect an output voltage on the output node to determine whether a short-circuit condition occurs, and to provide a detecting signal according to the output voltage on the output node in the short-circuit condition. The disable module is configured to provide a disable signal according to the detecting signal in the short-circuit condition, and operatively stop the disable signal in each cycle period of a clock signal. The driving module is configured to determine whether to generate the driving signal according to the disable signal and the clock signal. | 03-26-2015 |
20150061517 | Driving Circuit for Driving LED Load - A driving circuit includes a rectifier circuit and a LED driver integrated circuit. The rectifier circuit rectifies an ac power supply into a de power supply. The LED driver integrated circuit includes a regulator circuit, a voltage detector, a buck boost LED driver, and a common ground terminal. The regulator circuit regulates the dc power supply into a regulated voltage. The voltage detector detects whether the regulated voltage meets a voltage requirement and output the regulated voltage when the voltage requirement is met. The buck boost LED driver converts the regulated voltage detected into an output driving voltage according to a remaining voltage at a negative terminal of the LED load to drive the LED load. Voltage potentials at the common ground terminal and at a load ground terminal of the LED load are the same. | 03-05-2015 |
20140306679 | DRIVING CIRCUIT AND ERROR AMPLIFIER THEREOF - 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. | 10-16-2014 |
20140306678 | CHARGE MODULE, DRIVING CIRCUIT, AND OPERATING METHOD - 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. | 10-16-2014 |
20120182662 | Inrush Current Protection Circuit - An inrush current protection circuit for charging a load to a target voltage, in which the inrush current protection circuit includes a first charging circuit and a second charging circuit. The first charging circuit charges a load to a first stage voltage, and there is a voltage difference existing between the target voltage and the first stage voltage. The second charging circuit charges the load form the first stage voltage to the target voltage, in which the first charge circuit charges slower than the second charging circuit. | 07-19-2012 |
20120112660 | LED Circuit Having LED Driving Circuit with Smooth Transient Mechanism and Operation Method of the Same - A LED driving circuit having a smooth transient mechanism adapted in a LED circuit to drive a plurality of LED channels is provided. The LED driving circuit comprises: a dimming module, a dc-to-dc converter, a delay module and a plurality of current sink modules. A control module of the dc-to-dc converter generates a driving voltage according to the dimming voltage from the dimming module to control a gate of a power MOS to further turn on or turn off the LED channels. The delay module comprises delay units connected in series to delay the dimming voltage to generate a plurality of delay signals each at an output node of each of the delay units. Each of the current sink modules is connected to one of the LED channels to adjust the turn-on period according to one of the delay signals. A LED circuit operation method is disclosed herein as well. | 05-10-2012 |
20120112659 | LED Circuit Having LED Driving Circuit and Operation Method of the Same - A LED circuit is provided. The LED circuit comprises LED channels and a LED driving circuit. The LED driving circuit comprises: a current mirror, a dc-to-dc converter and current sink modules each connected between one of the LED channels and an output load to lock the voltage at the output load at a level of a setting voltage. The current mirror comprises an input branch to generate an input setting current according to a variable setting load and an output branch to generate an output setting current to further generate a variable reference voltage and the setting voltage. A control module of the dc-to-dc converter generates a driving voltage according the variable reference voltage and a feedback voltage to control a gate of the power MOS of the dc-to-dc converter to further control the operation of the LED channels. A LED circuit operation method is disclosed herein as well. | 05-10-2012 |
20120105035 | Buck Circuit Having Fast Transient Response Mechanism and Operation of the Same - A buck circuit having a fast transient response mechanism is provided. The buck circuit comprises a high side MOS, a low side MOS, a transient control module and an operation control module. The low side MOS is connected to the high side MOS at a connection point for generating an output voltage to an external load according to an input voltage from the high side MOS. The operation control module controls the operation of the high and the low side MOS according to the output voltage when the external load is in a heavy load state such that the transient control module is disabled. When the external load turns from the heavy load state to a light load state such that the output voltage raises over a predetermined level, the transient control module is enabled to turn on the low side MOS for discharging to pull down the output voltage. | 05-03-2012 |
20120098869 | Light Emitting Diode Circuit, Light Emitting Diode Driving Circuit, and Method for Driving Light Emitting Diode Channels - A light emitting diode driving circuit includes a DC-to-DC voltage converter, a pulse width modulator, a shifting circuit, and a plurality of current sink circuits. The DC-to-DC voltage converter generates a driving voltage on first ends of the light emitting diode channels, in which the DC-to-DC voltage converter includes a switch, and a magnitude of the driving voltage is correlated with the conduction time of the switch. The pulse width modulator generates a PWM signal having a duty cycle which drives the switch of the DC-to-DC voltage converter. The plurality of clock cycles on the shifting circuit delays the PWM signal to generate a plurality of phase signals, in which the phase signals have different phases. The current sink circuits are positioned to control the flows of current flowing through the light emitting diode channels according to the phase signals having different phases. | 04-26-2012 |
20120098456 | Light Emitting Diode Driving Circuit - 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. | 04-26-2012 |
20120098435 | Channel Detection Device - A channel detection device is disclosed in specification and drawing, where the channel detection circuit 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. | 04-26-2012 |
20120086357 | Light Emitting Diode Circuit, Light Emitting Diode Driving Circuit, Voltage Selection Circuit, and Method for Driving Thereof - 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. | 04-12-2012 |
20120043995 | Detection Circuit - A detection circuit is disclosed in specification and drawing, where the detection circuit includes a current source, a voltage-current converter and a current comparator. The voltage-current converter is configured to acquire a receiving current from the current source by comparing a reference voltage with an input voltage of a detecting terminal. The current comparator is configured to output an output voltage by comparing a steady current with an output current based on the receiving current. | 02-23-2012 |
20110298377 | LED Circuit and Operation Method of the Same - 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. | 12-08-2011 |
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 |
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 |
20110221501 | TRIMMING CIRCUIT - 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. | 09-15-2011 |
20110181573 | Power-Off Control Circuit and Liquid Crystal Display Panel Comprising the Same - 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. | 07-28-2011 |
20110181346 | Charge Pump Driving Circuit and Charge Pump System - 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. | 07-28-2011 |
20110084770 | Oscillator - 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. | 04-14-2011 |
20110084625 | Switching Circuit Adapted in LED Circuit - 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. | 04-14-2011 |
20110063009 | Voltage Trimming Circuit - 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. | 03-17-2011 |
20110043957 | Driver and Over-Current Protection Circuit Therein - 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. | 02-24-2011 |
20110018509 | Driver, Current Regulating Circuit Thereof, and Method of Current Regulation - 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. | 01-27-2011 |
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 |
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 |
20100253657 | LED Driving Circuit and Method of Controlling the Same - 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 lo 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. | 10-07-2010 |
20100253297 | Soft-Start Circuit - 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 2 | 10-07-2010 |
20100225373 | Delay Circuit - A delay circuit includes current sources, switches, a transistor switch, a charging unit and a comparator. Each of the switches is provided for receiving an enable signal to activate and convey one of the current sources. The transistor switch is activated for pulling down voltage of an operating node coupled to the switches. The charging unit provides an operating voltage for the operating node based on one of the current sources when the transistor switch is deactivated and one of the switches is activated to convey one of the current sources to the charging unit. The comparator is provided for comparing the operating voltage with a reference voltage. | 09-09-2010 |
20100225247 | 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. | 09-09-2010 |
20100214021 | Class AB Rail-to-Rail Operational Amplifier - 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. | 08-26-2010 |
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 |
20100213907 | Low Drop Out Linear Regulator - A low drop out linear regulator is provided. The low drop out linear regulator comprises an output PMOS, a load, a discharging circuit and an operational amplifier. The output PMOS comprises a source connected to a power supply and a drain having an output voltage and an output current. The drain is connected to a load circuit having a heavy and a light load period. The load is connected to the drain to generate a divided output voltage. The discharging circuit is connected to the drain to discharge the output current from the drain. The operational amplifier is to generate a control voltage according to the divided output voltage and a reference voltage; when the load circuit switches from the heavy to the light load period to make the divided output voltage higher than the reference voltage, the control voltage turns off the output PMOS and activates the discharging circuit. | 08-26-2010 |
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 |
20100052632 | DC/DC Converter and Current Sense Circuit Thereof - 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. | 03-04-2010 |
20100045256 | DC/DC Converter and Slope Compensation Circuit Thereof - A slope compensation circuit includes a first differential pair circuit, a current mirror unit, a first operating current generation circuit, and a transconductance compensation circuit. The first differential pair circuit is connected to a first current source and receives a pair of differential oscillation signals to generate a pair of differential currents corresponding to the differential oscillation signals. The current mirror unit is connected to the first differential pair circuit and mirrors the differential currents. The first operating current generation circuit is connected to the current mirror unit and generates a first operating current including the differential currents. The transconductance compensation circuit stabilizes a quiescent operating point of the first operating current generation circuit and receives the differential oscillation signals to generate an output current multiple times the value of the first operating current. | 02-25-2010 |
20090250773 | Semiconductor device - A semiconductor device includes a first metal region, a plurality of vias, a plurality of second metal regions, a plurality of openings and a third metal region. The first metal region conducts source/drain current. The second metal regions are electrically connected to the first metal region through the vias for conducting the source/drain current, in which each of the second metal regions is disposed in a distance from the adjacent second metal regions. The third metal region is electrically connected to the second metal regions through the openings, in which the resistance of the third metal region is smaller than the resistances of the first metal region and the second metal regions. | 10-08-2009 |
20090236670 | Semiconductor Device and a Manufacturing Process Thereof - A semiconductor device has a plurality of drain metal blocks, a plurality of source metal blocks, a plurality of polysilicon strips, a first source metal strip, a first drain metal strip, and a plurality of first conductive wires. Each of the source metal blocks is disposed between two of the drain metal blocks, and at least two of the polysilicon strips are correspondingly disposed across one of the drain metal blocks and one of the source metal blocks. The first source metal strip, in the absence of the polysilicon strips, is electrically connected to some of the source metal blocks. The first drain metal strip, in the absence of the polysilicon strips, is electrically connected to some of the drain metal blocks. The first conductive wires, coupled to the polysilicon strips, form a plurality of grids. | 09-24-2009 |
20090230881 | LED DRIVER AND CIRCUIT FOR CONTROLLING A POWER SWITCH TO PROVIDE A DRIVING VOLTAGE TO AT LEAST ONE LED - An LED driver circuit and its control circuit for controlling its power switch are provided. The LED driver includes a switch, a PWM controller, a current source and a signal controller. The switch has a first end outputting a driving voltage to at least one LED. The PWM controller provides a PWM signal. The current source provides a driving current flowing through the LED when a dimming control signal is asserted. The signal controller turns off the switch when the dimming control signal is de-asserted and relays the PWM signal from the PWM controller to the switch so that the switch is controlled by the PWM signal when the dimming control signal is asserted. | 09-17-2009 |
20090230880 | DRIVING CIRCUIT AND METHOD FOR LIGHT EMITTING DIODE - 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. | 09-17-2009 |
20090207109 | CIRCUIT AND METHOD FOR DRIVING LIGHT EMITTING DIODES - 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. | 08-20-2009 |
20090201056 | Preset Circuit of Audio Power Amplifier - A preset circuit of an audio power amplifier includes an inverter and a voltage drop device. The inverter receives an input signal to output an output signal, and includes a first switch and a second switch. The first switch is controlled with the input signal, and has a first terminal coupled to a power voltage and a second terminal for outputting the output signal. The second switch is controlled with the input signal, and has a third terminal for outputting the output signal and a fourth terminal coupled to a low reference voltage. The voltage drop device is coupled between the first terminal of the first switch and the power voltage and configured to lower the power voltage. The output signal is kept at a low level when the voltage drop device and the first switch are de-actuated due to the power voltage having a level below a first threshold. | 08-13-2009 |
20090200959 | Light-Emitting Diode Driving Circuit - A light-emitting diode driving circuit includes a control circuit, a transistor switch and a compensating circuit. The control circuit receives an oscillating signal to generate a pulse drive signal. The transistor switch is activated by the pulse drive signal such that an inductor is charged by an input voltage, in which the inductor is arranged to deliver an inducting current to at least one light-emitting diode when the transistor switch is deactivated. The compensating circuit is coupled between the control circuit and a capacitor provided for reducing ripples of an output voltage corresponding to the inducting current. The compensating circuit performs a charging and discharging operation along with the capacitor when controlled by a dimming control signal provided to control brightness of the light-emitting diode. | 08-13-2009 |
20090092267 | SWITCHING AUDIO POWER AMPLIFIER WITH DE-NOISE FUNCTION - The invention provides a switching audio power amplifier with de-noise function, including a first comparator, a second comparator, a logic control unit, a de-noise circuit, and a bridge circuit. The first comparator and the second comparator respectively generate the first PWM signal and the second PWM signal, and then the logic control unit performs logic operation to generate a third PWM signal and a fourth PWM signal. If the pulse width of the third PWM signal (or the fourth PWM signal) is lower than a threshold, the de-noise circuit increases the pulse width of the third PWM signal or the fourth PWM signal and outputs the fifth PWM signal and the sixth PWM signal to drive the bridge circuit. Next, the bridge circuit conducts a driving current alternately flowing to and from a load according to the firth PWM signal and the sixth PWM signal. | 04-09-2009 |
20090015327 | SWITCHING AUDIO POWER AMPLIFIER WITH DE-NOISE FUNCTION - The invention provides a switching audio power amplifier with de-noise function including a pulse width modulator, a de-noise circuit and a bridge circuit. The pulse width modulator performs pulse width moderation to generate the first and second PWM signals according to an input audio signal. The de-noise circuit receives the first and second PWM signals. And the bridge circuit conducts a driving current alternately flowing to and from a load according to the control signals output from the de-noise circuit. | 01-15-2009 |
20080303590 | POWER AMPLIFIER WITH NOISE SHAPING FUNCTION - A power amplifier with noise shaping function is provided. The power amplifier includes a differential mode integrator, an integration and adjustment unit and a switch unit. The differential mode integrator is used for receiving a differential mode input signal and a differential mode output signal, and outputting a differential mode first signal. The integration and adjustment unit is coupled to the differential mode integrator for receiving the first signal and an output signal and outputting a single-end mode second signal. The switch unit is used for receiving the second signal and outputting the differential mode output signal to drive the load. The present invention uses a common mode input signal instead of the single-end input signal to eliminate the common mode noise, and uses a 2 | 12-11-2008 |
20080284502 | CURRENT BIASING CIRCUIT - A current biasing circuit is provided, which is designed to suppress reference current drift caused by temperature variation with a low overall temperature coefficient of a constant-voltage circuit and at least one resistor. The constant-voltage circuit comprises a diode and/or a diode-connected transistor. This current biasing circuit is based on a current mirror architecture, is easy to implement, and is a relatively temperature-independent current source. | 11-20-2008 |
20080238540 | POWER AMPLIFIER WITH NOISE SHAPING - A power amplifier with noise shaping is disclosed. The power amplifier with noise shaping is able to minimize the noise interference a regular power amplifier encounters. The power amplifier includes a differential-mode integrator, a driving unit, and a low pass filter and integration unit. The differential-mode integrator receives a differential-mode input signal and a differential-mode feedback signal and performs integration operations to output a differential-mode intermediate signal. The driving unit outputs a differential-mode output signal and drives a load according to the differential-mode intermediate signal. The low pass filter and integration unit performs a filtering operation on the differential-mode output signal and integration operations to output the differential-mode feedback signal to the differential-mode integrator. | 10-02-2008 |