TWI420956B - Led driver and start-up feedback circuit therein - Google Patents
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Description
本發明是有關於一種驅動電路,且特別是有關於一種發光二極體驅動器。This invention relates to a drive circuit and, more particularly, to a light emitting diode driver.
一般而言,發光二極體(LED)驅動器係將輸入電壓轉換為所需之輸出電壓,以驅動一或多個連接之發光二極體。然而,發光二極體驅動器通常會因某些情況(如:接收不穩定的啟始輸入電壓)在啟動過程中發生錯誤,而無法適當地進行啟動,因此經常造成發光二極體無法如預期地正常運作。In general, a light emitting diode (LED) driver converts an input voltage to a desired output voltage to drive one or more connected light emitting diodes. However, LED drivers often fail to start properly due to certain conditions (such as receiving an unstable start input voltage) during startup, which often causes the LED to fail as expected. working normally.
本發明之一目的是在提供一種發光二極體驅動器中之啟始迴授電路,藉以確保發光二極體驅動器能正常啟動。It is an object of the present invention to provide a start feedback circuit in a light emitting diode driver to ensure that the light emitting diode driver can be normally started.
本發明之另一目的是在提供一種發光二極體驅動器,藉以正常穩定地操作而驅動發光二極體。Another object of the present invention is to provide a light emitting diode driver for driving a light emitting diode in a normally stable operation.
本發明之一技術樣態係關於一種發光二極體驅動器中之啟始迴授電路,且此啟始迴授電路包含至少一個迴授次電路。迴授次電路包含第一電流單元、第二電流單元、第三電流單元、第四電流單元以及鏡射單元。第一電流單元係由接地電壓進行偏壓,以產生第一電流。第二電流單元係用以根據第一電流產生第二電流。第三電流單元係用以接收發光二極體迴授電壓,以產生第一電流以及第一控制電壓。第四電流單元係用以接收第一控制電壓,以產生由第二電流鏡射而得之第三電流,並感應出相對應第一控制電壓之第四電流。鏡射單元係用以產生第四電流,並鏡射第四電流以產生相對應第四電流之輸出電流,其中輸出電流係轉換為迴授電壓,以推升發光二極體驅動器之輸出電壓以及相對應輸出電壓之發光二極體迴授電壓。One aspect of the present invention relates to a start feedback circuit in a light emitting diode driver, and the start feedback circuit includes at least one feedback subcircuit. The feedback subcircuit includes a first current unit, a second current unit, a third current unit, a fourth current unit, and a mirror unit. The first current unit is biased by a ground voltage to generate a first current. The second current unit is configured to generate a second current according to the first current. The third current unit is configured to receive the LED feedback voltage to generate the first current and the first control voltage. The fourth current unit is configured to receive the first control voltage to generate a third current that is mirrored by the second current, and induce a fourth current corresponding to the first control voltage. The mirroring unit is configured to generate a fourth current and mirror the fourth current to generate an output current corresponding to the fourth current, wherein the output current is converted into a feedback voltage to boost the output voltage of the LED driver and The light-emitting diode feedback voltage corresponding to the output voltage.
本發明之另一技術樣態係關於一種發光二極體驅動器中之啟始迴授電路,且此啟始迴授電路包含至少一個迴授次電路。迴授次電路包含第一P型電晶體、第一N型電晶體、第二P型電晶體、第二N型電晶體、以及鏡射單元。第一P型電晶體具有第一控制端以及第一端,其中第一控制端係由低位準電源電壓進行偏壓,而第一端係經由第一電流源耦接於高位準電源電壓。第一N型電晶體具有第二控制端以及第二端,其中第二控制端係耦接於第一P型電晶體之第一端,第二端係經由第二電流源耦接於高位準電源電壓。第二P型電晶體具有第三控制端以及第三端,其中第三控制端係用以接收發光二極體迴授電壓,第三端係經由第一電流源耦接於高位準電源電壓。第二N型電晶體具有第四控制端以及第四端,其中第四控制端係耦接於第二P型電晶體之第三端,第四端係經由第二電流源所鏡射而得之第三電流源耦接於高位準電源電壓。鏡射單元係由第三P型電晶體以及第四P型電晶體所組成,其中第三P型電晶體具有第五控制端以及第五端,第五控制端與第五端耦接並耦接於第二N型電晶體之第四端,且第四P型電晶體具有第六控制端以及第六端,第六控制端係耦接於第三P型電晶體之第五控制端,第六端係經由電阻單元耦接於低位準電源電壓並產生輸出電流,且輸出電流係由電阻單元轉換為迴授電壓,以推升發光二極體驅動器之輸出電壓以及相對應輸出電壓之發光二極體迴授電壓。Another aspect of the present invention is directed to a start feedback circuit in a light emitting diode driver, and the start feedback circuit includes at least one feedback subcircuit. The feedback subcircuit includes a first P-type transistor, a first N-type transistor, a second P-type transistor, a second N-type transistor, and a mirror unit. The first P-type transistor has a first control end and a first end, wherein the first control end is biased by a low level supply voltage, and the first end is coupled to the high level supply voltage via the first current source. The first N-type transistor has a second control end and a second end, wherein the second control end is coupled to the first end of the first P-type transistor, and the second end is coupled to the high level via the second current source voltage. The second P-type transistor has a third control end and a third end, wherein the third control end is configured to receive the LED feedback voltage, and the third end is coupled to the high level supply voltage via the first current source. The second N-type transistor has a fourth control end and a fourth end, wherein the fourth control end is coupled to the third end of the second P-type transistor, and the fourth end is mirrored by the second current source The third current source is coupled to the high level supply voltage. The mirror unit is composed of a third P-type transistor and a fourth P-type transistor, wherein the third P-type transistor has a fifth control end and a fifth end, and the fifth control end is coupled to the fifth end and coupled Connected to the fourth end of the second N-type transistor, and the fourth P-type transistor has a sixth control end and a sixth end, and the sixth control end is coupled to the fifth control end of the third P-type transistor. The sixth end is coupled to the low level supply voltage via the resistor unit and generates an output current, and the output current is converted by the resistance unit into a feedback voltage to boost the output voltage of the LED driver and the corresponding output voltage. The diode feedback voltage.
本發明之又一技術樣態係關於一種發光二極體驅動器,其包含啟始迴授電路、操作迴授電路以及多工器。啟始迴授電路具有複數個第一端用以接收複數個發光二極體迴授電壓,其中每一個發光二極體迴授電壓係由至少一發光二極體所傳送而來,且發光二極體係耦接於發光二極體驅動器中用以輸出輸出電壓之輸出端,而啟始迴授電路係根據上述發光二極體迴授電壓產生啟始迴授電壓。操作迴授電路具有複數個第二端用以接收上述發光二極體迴授電壓,且操作迴授電路係根據上述發光二極體迴授電壓產生操作迴授電壓。多工器耦接於啟始迴授電路以及操作迴授電路,以選擇啟始迴授電壓或操作迴授電壓。其中,當發光二極體驅動器開始啟動時,多工器選擇啟始迴授電壓以開始推升輸出電壓,而當該輸出電壓增加至一特定值時,多工器則是選擇操作迴授電壓以接續推升輸出電壓。Yet another aspect of the present invention is directed to a light emitting diode driver including a start feedback circuit, an operation feedback circuit, and a multiplexer. The start feedback circuit has a plurality of first ends for receiving a plurality of LED feedback voltages, wherein each of the LED feedback voltages is transmitted by at least one LED, and the LEDs are illuminated The pole system is coupled to the output end of the LED driver for outputting the output voltage, and the start feedback circuit generates the initial feedback voltage according to the LED feedback voltage. The operation feedback circuit has a plurality of second ends for receiving the LED feedback voltage, and the operation feedback circuit generates an operation feedback voltage according to the LED feedback voltage. The multiplexer is coupled to the start feedback circuit and the operation feedback circuit to select the start feedback voltage or the operation feedback voltage. Wherein, when the LED driver starts to start, the multiplexer selects to initiate the feedback voltage to start to push up the output voltage, and when the output voltage increases to a specific value, the multiplexer selects the operation feedback voltage. Push up the output voltage.
本發明之再一技術樣態係關於一種發光二極體驅動器,其包含啟始迴授電路、操作迴授電路、多工器、以及補償單元。啟始迴授電路具有複數個第一端,且每一個第一端係經由至少一發光二極體耦接於發光二極體驅動器中用以輸出輸出電壓之輸出端,而上述第一端係用以接收複數個發光二極體迴授電壓,且每一個發光二極體迴授電壓係由發光二極體所傳送而來,其中啟始迴授電路係根據上述發光二極體迴授電壓產生啟始迴授電壓。操作迴授電路具有複數個第二端,且每一個第二端係經由發光二極體耦接於發光二極體驅動器之輸出端,上述第二端係用以接收發光二極體迴授電壓,且每一個發光二極體迴授電壓係由發光二極體所傳送而來,其中操作迴授電路係根據上述發光二極體迴授電壓產生操作迴授電壓。多工器係用以在發光二極體驅動器開始啟動時選擇啟始迴授電壓,或是在輸出電壓增加至一特定值時選擇操作迴授電壓。補償單元係用以比較啟始迴授電壓和參考電壓,以輸出補償信號用於輸出電壓之初始推升動作,或是比較操作迴授電壓和參考電壓,以輸出補償信號用於輸出電壓之接續推升動作。Still another aspect of the present invention relates to a light emitting diode driver including a start feedback circuit, an operation feedback circuit, a multiplexer, and a compensation unit. The first feedback system has a plurality of first ends, and each of the first ends is coupled to the output terminal of the LED driver for outputting an output voltage via at least one light emitting diode, and the first end system is The method is configured to receive a plurality of light-emitting diode feedback voltages, and each of the light-emitting diode feedback voltages is transmitted by the light-emitting diodes, wherein the start feedback circuit is based on the light-emitting diode feedback voltage The initial feedback voltage is generated. The operation feedback circuit has a plurality of second ends, and each of the second ends is coupled to the output end of the LED driver via the LED, and the second end is configured to receive the LED feedback voltage And each of the light-emitting diode feedback voltages is transmitted by the light-emitting diodes, wherein the operation feedback circuit generates the operation feedback voltage according to the light-emitting diode feedback voltage. The multiplexer is used to select the start feedback voltage when the LED driver starts to start, or to select the operation feedback voltage when the output voltage is increased to a specific value. The compensation unit is configured to compare the initial feedback voltage and the reference voltage to output a compensation signal for the initial push-up action of the output voltage, or to compare the operation feedback voltage and the reference voltage to output a compensation signal for the output voltage connection. Push up the action.
根據本發明之技術內容,應用前述發光二極體驅動器及其中啟始迴授電路,可於發光二極體驅動器開始啟動時,確保發光二極體驅動器正常且良好地操作,進而穩定地驅動發光二極體。According to the technical content of the present invention, the light-emitting diode driver and the start-up feedback circuit thereof can be used to ensure that the LED driver is normally and well operated when the LED driver is started, thereby stably driving the LED. Diode.
第1圖係依照本發明實施例繪示一種發光二極體(LED)驅動器的方塊示意圖。LED驅動器100係將輸入電壓VIN轉換為輸出電壓VOUT,藉以驅動一或多個LED 102通道,其中每一個通道均包括一或多個串連相接之LED 102。在一實施例中,LED驅動器100係用以驅動八個白光LED所形成的通道,且每一個通道均包括多個串連相接之白光LED。此外,LED驅動器100可設計成一個積體電路(IC)晶片。FIG. 1 is a block diagram showing a light emitting diode (LED) driver according to an embodiment of the invention. The LED driver 100 converts the input voltage VIN to an output voltage VOUT, thereby driving one or more LEDs 102 channels, each of which includes one or more LEDs 102 connected in series. In one embodiment, the LED driver 100 is configured to drive channels formed by eight white LEDs, and each of the channels includes a plurality of white LEDs connected in series. Further, the LED driver 100 can be designed as an integrated circuit (IC) wafer.
LED驅動器100包括驅動單元110、電晶體開關120、比較器130、補償單元(如:誤差放大器140)、啟始迴授電路150、操作迴授電路160以及多工器170。The LED driver 100 includes a driving unit 110, a transistor switch 120, a comparator 130, a compensation unit (such as an error amplifier 140), a start feedback circuit 150, an operation feedback circuit 160, and a multiplexer 170.
啟始迴授電路150具有複數個第一端152,且每一個第一端152係相對應地耦接於一個LED 102所形成的通道。操作迴授電路160具有複數個第二端162,且每一個第二端162亦相對應地耦接於一個LED 102通道。換言之,每一個LED 102通道均耦接於上述第一端152其中一者以及上述第二端162其中一者,並耦接於用以輸出輸出電壓VOUT的輸出端。The start feedback circuit 150 has a plurality of first ends 152, and each of the first ends 152 is correspondingly coupled to a channel formed by one of the LEDs 102. The operation feedback circuit 160 has a plurality of second ends 162, and each of the second ends 162 is correspondingly coupled to one LED 102 channel. In other words, each of the LEDs 102 is coupled to one of the first ends 152 and one of the second ends 162 and coupled to an output for outputting the output voltage VOUT.
啟始迴授電路150的第一端152係分別接收由LED 102所傳送而來之複數個LED迴授電壓LFB,使得啟始迴授電路150藉此產生啟始迴授電壓SFB。在此,如第1圖所示,LED迴授電壓LFB係指與啟始迴授電路150和操作迴授電路160連接之第一個LED 102的陰極電壓,或是與其陰極電壓相對應的電壓。同樣地,操作迴授電路160的第二端162係分別接收由LED 102所傳送而來之LED迴授電壓LFB,使得操作迴授電路160藉此產生操作迴授電壓OFB。在一實施例中,操作迴授電路160係根據所接收到之LED迴授電壓中之最小LED迴授電壓而產生操作迴授電壓OFB。The first end 152 of the start feedback circuit 150 receives the plurality of LED feedback voltages LFB transmitted by the LEDs 102, respectively, such that the start feedback circuit 150 thereby generates the start feedback voltage SFB. Here, as shown in FIG. 1, the LED feedback voltage LFB refers to the cathode voltage of the first LED 102 connected to the start feedback circuit 150 and the operation feedback circuit 160, or a voltage corresponding to the cathode voltage thereof. . Similarly, the second end 162 of the operational feedback circuit 160 receives the LED feedback voltage LFB transmitted by the LED 102, respectively, such that the operational feedback circuit 160 thereby generates the operational feedback voltage OFB. In one embodiment, the operational feedback circuit 160 generates an operational feedback voltage OFB based on the minimum LED feedback voltage of the received LED feedback voltage.
多工器170係耦接於啟始迴授電路150以及操作迴授電路160,用以選擇啟始迴授電壓SFB或操作迴授電壓OFB作為補償迴授電壓FB。誤差放大器140係用以比較補償迴授電壓FB和參考電壓VREF,以輸出補償信號VC(通常為電壓信號)。比較器130對補償信號VC和振盪信號OS進行比較,並產生比較信號CS。驅動單元110則接收比較信號CS,並因此輸出脈衝驅動信號PS,藉以開啟電晶體開關120。The multiplexer 170 is coupled to the start feedback circuit 150 and the operation feedback circuit 160 for selecting the start feedback voltage SFB or the operation feedback voltage OFB as the compensation feedback voltage FB. The error amplifier 140 is for comparing the compensated feedback voltage FB and the reference voltage VREF to output a compensation signal VC (typically a voltage signal). The comparator 130 compares the compensation signal VC with the oscillating signal OS and produces a comparison signal CS. The driving unit 110 then receives the comparison signal CS and thus outputs the pulse driving signal PS, thereby turning on the transistor switch 120.
電晶體開關120的工作週期(duty ratio)決定輸出電壓VOUT和輸入電壓VIN之間的比例關係。當脈衝驅動信號PS開啟電晶體開關120時,輸入電壓VIN會對電感104進行充電;反之,當電晶體開關120未藉由脈衝驅動信號PS開啟時,則電感104會傳送感應電流IL,因而產生輸出電壓VOUT,並在每一個通道中產生流經LED 102的二極體電流IOUT,而LED 102的亮度便是根據其流經之二極體電流IOUT大小來進行變化。The duty ratio of the transistor switch 120 determines the proportional relationship between the output voltage VOUT and the input voltage VIN. When the pulse driving signal PS turns on the transistor switch 120, the input voltage VIN charges the inductor 104; conversely, when the transistor switch 120 is not turned on by the pulse driving signal PS, the inductor 104 transmits the induced current IL, thereby generating The voltage VOUT is output and a diode current IOUT flowing through the LED 102 is generated in each channel, and the brightness of the LED 102 varies according to the magnitude of the diode current IOUT through which it flows.
在操作上,當LED驅動器100開始啟動時,多工器170會選擇啟始迴授電壓SFB作為補償迴授電壓FB,以用於輸出電壓VOUT之初始推升動作,而當輸出電壓VOUT增加至一特定值時,多工器170會選擇操作迴授電壓OFB作為補償迴授電壓FB,以用於輸出電壓VOUT之接續推升動作。In operation, when the LED driver 100 starts to start, the multiplexer 170 selects the start feedback voltage SFB as the compensation feedback voltage FB for the initial push-up action of the output voltage VOUT, and when the output voltage VOUT is increased to At a specific value, the multiplexer 170 selects the operation feedback voltage OFB as the compensation feedback voltage FB for the successive push-up operation of the output voltage VOUT.
具體地來說,當LED驅動器100開始啟動時,補償迴授電壓FB為0V,且參考電壓VREF自0V逐漸增加,使得補償信號VC產生,且輸出電壓VOUT因而自0V逐漸增加。當輸出電壓VOUT增加至一特定值時,LED迴授電壓LFB會藉此產生並逐漸增加。此時,啟始迴授電路150相對應地產生啟始迴授電壓SFB,並由多工器170進行選釋作為補償迴授電壓FB。Specifically, when the LED driver 100 starts to start, the compensation feedback voltage FB is 0V, and the reference voltage VREF gradually increases from 0V, so that the compensation signal VC is generated, and the output voltage VOUT thus gradually increases from 0V. When the output voltage VOUT is increased to a specific value, the LED feedback voltage LFB is thereby generated and gradually increased. At this time, the start feedback circuit 150 correspondingly generates the start feedback voltage SFB, and is selectively released by the multiplexer 170 as the compensation feedback voltage FB.
當啟始迴授電壓SFB和參考電壓VREF增加至某一個值時,具通常知識者所謂的緩啟動(soft-start)程序便已完成,而緩啟動結束信號SEL會傳送至多工器170中,使得多工器170進行切換,並選擇操作迴授電路160所產生之操作迴授電壓OFB作為補償迴授電壓FB,使輸出電壓VOUT接續的推升動作得以繼續。When the start feedback voltage SFB and the reference voltage VREF are increased to a certain value, the so-called soft-start program of the conventional knowledge is completed, and the slow start signal SEL is transmitted to the multiplexer 170. The multiplexer 170 is caused to switch, and the operation feedback voltage OFB generated by the operation feedback circuit 160 is selected as the compensation feedback voltage FB, and the push-up operation of the output voltage VOUT is continued.
第2圖係依照本發明實施例繪示一種如第1圖所示之啟始迴授電路的方塊示意圖。啟始迴授電路可更包括複數個彼此並聯相接的迴授次電路200以及與迴授次電路200連接的電阻單元210(如:電阻R),其中每一個迴授次電路200均接收一個相對應的LED迴授電壓LFB,並藉此輸出一個輸出電流。在本實施例中,啟始迴授電路包括八個迴授次電路200,其中第1迴授次電路200輸出輸出電流IS1,第2迴授次電路200輸出輸出電流IS2,依此類推。然後,電阻單元210將電流IS1、IS2、...以及IS8所組成的總電流轉換為啟始迴授電壓SFB。FIG. 2 is a block diagram showing a start feedback circuit as shown in FIG. 1 according to an embodiment of the invention. The start feedback circuit may further include a plurality of feedback sub-circuits 200 connected in parallel with each other and a resistance unit 210 (eg, a resistor R) connected to the feedback sub-circuit 200, wherein each of the feedback sub-circuits 200 receives one The corresponding LEDs feedback the voltage LFB and thereby output an output current. In the present embodiment, the start feedback circuit includes eight feedback sub-circuits 200, wherein the first feedback circuit 200 outputs an output current IS1, the second feedback circuit 200 outputs an output current IS2, and so on. Then, the resistance unit 210 converts the total current composed of the currents IS1, IS2, ..., and IS8 into the start feedback voltage SFB.
第3圖係依照本發明實施例繪示一種如第2圖所示之迴授次電路的方塊示意圖。迴授次電路200包括第一電流單元310、第二電流單元320、第三電流單元330、第四電流單元340以及鏡射單元350。第一電流單元310係由低位準電源電壓(如:接地電壓GND)進行偏壓,以產生(assert)第一電流源I1。第二電流單元320係根據第一電流源I1產生第二電流源I2。第三電流單元330係接收上述LED迴授電壓LFB其中一者,以產生第一電流以及第一控制電壓FC。第四電流單元340係接收第一控制電壓FC,以產生由第二電流源I2所鏡射而得之第三電流源I3,並感應出相對應第一控制電壓FC的第四電流I4。鏡射單元350產生第四電流I4(或稱鏡射電流),並對第四電流I4進行鏡射動作,以產生相對應第四電流I4之輸出電流IS,因而產生啟始迴授電壓SFB。在本實施例中,當LED迴授電壓LFB增加時,第一控制電壓FC會隨之增加,使得第四電流I4和啟始迴授電壓SFB因此增加。FIG. 3 is a block diagram showing a feedback sub-circuit as shown in FIG. 2 according to an embodiment of the invention. The feedback sub-circuit 200 includes a first current unit 310, a second current unit 320, a third current unit 330, a fourth current unit 340, and a mirror unit 350. The first current unit 310 is biased by a low level supply voltage (eg, ground voltage GND) to assert the first current source I1. The second current unit 320 generates a second current source I2 according to the first current source I1. The third current unit 330 receives one of the LED feedback voltages LFB to generate a first current and a first control voltage FC. The fourth current unit 340 receives the first control voltage FC to generate a third current source I3 mirrored by the second current source I2, and induces a fourth current I4 corresponding to the first control voltage FC. The mirroring unit 350 generates a fourth current I4 (or a mirror current) and mirrors the fourth current I4 to generate an output current IS corresponding to the fourth current I4, thereby generating a start feedback voltage SFB. In the present embodiment, when the LED feedback voltage LFB is increased, the first control voltage FC is increased, so that the fourth current I4 and the start feedback voltage SFB are thus increased.
在本實施例中,第一電流單元310更包括第一P型電晶體(如:P型金屬氧化物半導體場效電晶體MP1),其中電晶體MP1的閘極由接地電壓GND進行偏壓,電晶體MP1的源極經由第一電流源I1耦接於高位準電源電壓VD,而電晶體MP1的汲極則是耦接於接地電壓GND。第二電流單元320更包括第一N型電晶體(如:N型金屬氧化物半導體場效電晶體MN1),其中電晶體MN1的閘極耦接於電晶體MP1的源極,電晶體MN1的汲極經由第二電流源I2耦接於高位準電源電壓VD,而電晶體MN1的源極則是耦接於接地電壓GND。In this embodiment, the first current unit 310 further includes a first P-type transistor (eg, a P-type metal oxide semiconductor field effect transistor MP1), wherein the gate of the transistor MP1 is biased by the ground voltage GND. The source of the transistor MP1 is coupled to the high level supply voltage VD via the first current source I1, and the drain of the transistor MP1 is coupled to the ground voltage GND. The second current unit 320 further includes a first N-type transistor (eg, an N-type metal oxide semiconductor field effect transistor MN1), wherein the gate of the transistor MN1 is coupled to the source of the transistor MP1, and the transistor MN1 The drain is coupled to the high level supply voltage VD via the second current source I2, and the source of the transistor MN1 is coupled to the ground voltage GND.
第三電流單元330更包括第二P型電晶體(如:P型金屬氧化物半導體場效電晶體MP2),其中電晶體MP2的閘極接收LED迴授電壓LFB,電晶體MP2的源極經由第一電流源I1耦接於高位準電源電壓VD,而電晶體MP2的汲極則是耦接於接地電壓GND。第四電流單元340更包括第二N型電晶體(如:N型金屬氧化物半導體場效電晶體MN2),其中電晶體MN2的閘極耦接於電晶體MP2的源極,電晶體MN2的汲極經由第三電流源I3耦接於高位準電源電壓VD,而電晶體MN2的源極則是耦接於接地電壓GND。The third current unit 330 further includes a second P-type transistor (eg, P-type metal oxide semiconductor field effect transistor MP2), wherein the gate of the transistor MP2 receives the LED feedback voltage LFB, and the source of the transistor MP2 is via The first current source I1 is coupled to the high level supply voltage VD, and the drain of the transistor MP2 is coupled to the ground voltage GND. The fourth current unit 340 further includes a second N-type transistor (eg, an N-type metal oxide semiconductor field effect transistor MN2), wherein the gate of the transistor MN2 is coupled to the source of the transistor MP2, and the transistor MN2 The drain is coupled to the high level supply voltage VD via the third current source I3, and the source of the transistor MN2 is coupled to the ground voltage GND.
鏡射單元350由第三P型電晶體(如:P型金屬氧化物半導體場效電晶體MP3)以及第四P型電晶體(如:P型金屬氧化物半導體場效電晶體MP4)所組成,其中電晶體MP3的閘極與汲極耦接,並耦接於電晶體MN2的汲極,電晶體MP4的閘極耦接於電晶體MP3的閘極,電晶體MP4的汲極經由電阻單元210耦接於接地電壓GND,並產生與電晶體MP3所產生之第四電流I4相對應的輸出電流IS,而電晶體MP3和MP4的源極則是耦接於高位準電源電壓VD。在一實施例中,電晶體MN1的大小與電晶體MN2的大小相同。The mirror unit 350 is composed of a third P-type transistor (such as a P-type metal oxide semiconductor field effect transistor MP3) and a fourth P-type transistor (such as a P-type metal oxide semiconductor field effect transistor MP4). The gate of the transistor MP3 is coupled to the drain and coupled to the drain of the transistor MN2, the gate of the transistor MP4 is coupled to the gate of the transistor MP3, and the drain of the transistor MP4 is via the resistor unit. The 210 is coupled to the ground voltage GND and generates an output current IS corresponding to the fourth current I4 generated by the transistor MP3, and the sources of the transistors MP3 and MP4 are coupled to the high level supply voltage VD. In an embodiment, the size of the transistor MN1 is the same as the size of the transistor MN2.
在操作上,當LED驅動器開始啟動時,LED迴授電壓LFB的暫態電壓為0V。此時,第四電流I4和輸出電流IS尚未產生。接著,當電壓LFB逐漸增加時,電壓FC隨之增加,使得電流I4因而產生並逐漸增加,且電流IS亦隨之產生並逐漸增加。如此一來,迴授電壓SFB便可相對應地產生而逐漸增加,藉以供選擇作為補償迴授電壓FB(如第1圖所示)。接著,當迴授電壓SFB增加至某個值時,緩啟動程序便告完成。然後,電壓OFB會取代電壓SFB,以供選擇作為補償迴授電壓FB(如上所述)。因此,由啟始迴授電路所產生之迴授電壓SFB,可用以確保LED驅動器在開始啟動時可正常運作或啟動,而不論操作迴授電路是否與LED驅動器的啟動程序相關。In operation, when the LED driver starts to start, the transient voltage of the LED feedback voltage LFB is 0V. At this time, the fourth current I4 and the output current IS have not yet been generated. Then, as the voltage LFB gradually increases, the voltage FC increases, so that the current I4 is thus generated and gradually increased, and the current IS is also generated and gradually increased. In this way, the feedback voltage SFB can be correspondingly generated and gradually increased, thereby being selected as the compensation feedback voltage FB (as shown in FIG. 1). Then, when the feedback voltage SFB is increased to a certain value, the slow start procedure is completed. The voltage OFB is then replaced by the voltage SFB for selection as the compensated feedback voltage FB (as described above). Therefore, the feedback voltage SFB generated by the start feedback circuit can be used to ensure that the LED driver can operate or start normally when starting up, regardless of whether the operation feedback circuit is associated with the LED driver startup procedure.
由上述本發明之實施例可知,應用前述發光二極體驅動器及其中啟始迴授電路,可於發光二極體驅動器開始啟動時,確保發光二極體驅動器正常且良好地操作,進而穩定地驅動發光二極體。According to the embodiment of the present invention, the LED driver and the initiating feedback circuit thereof can ensure that the LED driver is normally and well operated when the LED driver starts to be activated, thereby stably Drive the light-emitting diode.
雖然本發明已以實施方式揭露如上,然其並非用以限定本發明,任何熟習此技藝者,在不脫離本發明之精神和範圍內,當可作各種之更動與潤飾,因此本發明之保護範圍當視後附之申請專利範圍所界定者為準。Although the present invention has been disclosed in the above embodiments, it is not intended to limit the present invention, and the present invention can be modified and modified without departing from the spirit and scope of the present invention. The scope is subject to the definition of the scope of the patent application attached.
100...發光二極體驅動器100. . . LED driver
102...發光二極體102. . . Light-emitting diode
104...電感104. . . inductance
110...驅動單元110. . . Drive unit
120...電晶體開關120. . . Transistor switch
130...比較器130. . . Comparators
140...誤差放大器140. . . Error amplifier
150...啟始迴授電路150. . . Start feedback circuit
152...啟始迴授電路的第一端152. . . Start the first end of the feedback circuit
160...操作迴授電路160. . . Operation feedback circuit
162...操作迴授電路的第二端162. . . Operating the second end of the feedback circuit
170...多工器170. . . Multiplexer
200...迴授次電路200. . . Feedback subcircuit
210...電阻單元210. . . Resistor unit
310...第一電流單元310. . . First current unit
320...第二電流單元320. . . Second current unit
330...第三電流單元330. . . Third current unit
340...第四電流單元340. . . Fourth current unit
350...鏡射單元350. . . Mirror unit
第1圖係依照本發明實施例繪示一種發光二極體(LED)驅動器的方塊示意圖。FIG. 1 is a block diagram showing a light emitting diode (LED) driver according to an embodiment of the invention.
第2圖係依照本發明實施例繪示一種如第1圖所示之啟始迴授電路的方塊示意圖。FIG. 2 is a block diagram showing a start feedback circuit as shown in FIG. 1 according to an embodiment of the invention.
第3圖係依照本發明實施例繪示一種如第2圖所示之迴授次電路的方塊示意圖。FIG. 3 is a block diagram showing a feedback sub-circuit as shown in FIG. 2 according to an embodiment of the invention.
100...發光二極體驅動器100. . . LED driver
102...發光二極體102. . . Light-emitting diode
104...電感104. . . inductance
110...驅動單元110. . . Drive unit
120...電晶體開關120. . . Transistor switch
130...比較器130. . . Comparators
140...誤差放大器140. . . Error amplifier
150...啟始迴授電路150. . . Start feedback circuit
152...啟始迴授電路的第一端152. . . Start the first end of the feedback circuit
160...操作迴授電路160. . . Operation feedback circuit
162...操作迴授電路的第二端162. . . Operating the second end of the feedback circuit
170...多工器170. . . Multiplexer
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US6621235B2 (en) * | 2001-08-03 | 2003-09-16 | Koninklijke Philips Electronics N.V. | Integrated LED driving device with current sharing for multiple LED strings |
TW200729678A (en) * | 2006-01-27 | 2007-08-01 | Weltrend Semiconductor Inc | LED drive circuit with stable output current source |
TW200830081A (en) * | 2007-01-02 | 2008-07-16 | Chunghwa Picture Tubes Ltd | Current controlling apparatus |
US20080224632A1 (en) * | 2007-03-14 | 2008-09-18 | Ippei Noda | Constant current circuit and light emitting diode drive circuit |
US20080315773A1 (en) * | 2007-06-21 | 2008-12-25 | Sung-Man Pang | Light emitting diode driving circuit |
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Patent Citations (5)
Publication number | Priority date | Publication date | Assignee | Title |
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US6621235B2 (en) * | 2001-08-03 | 2003-09-16 | Koninklijke Philips Electronics N.V. | Integrated LED driving device with current sharing for multiple LED strings |
TW200729678A (en) * | 2006-01-27 | 2007-08-01 | Weltrend Semiconductor Inc | LED drive circuit with stable output current source |
TW200830081A (en) * | 2007-01-02 | 2008-07-16 | Chunghwa Picture Tubes Ltd | Current controlling apparatus |
US20080224632A1 (en) * | 2007-03-14 | 2008-09-18 | Ippei Noda | Constant current circuit and light emitting diode drive circuit |
US20080315773A1 (en) * | 2007-06-21 | 2008-12-25 | Sung-Man Pang | Light emitting diode driving circuit |
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