TW201228458A - Driving circuit, controller and method thereof for powering LED sources - Google Patents

Abstract

A driving circuit for powering a plurality of light-emitting diode (LED) light sources includes a power converter and a plurality of current balance controllers. The power converter receives an input voltage and provides a regulated voltage to the LED light sources. The current balance controllers coupled to the power converter control a plurality of currents through the LED light sources respectively. The current balance controllers receive a first reference signal indicative of a target average level and a second reference signal indicative of a maximum transient level, and regulate an average current of each of the currents to the target average level and a transient level of each of the currents within the maximum transient level.

Description

201228458 VI. DESCRIPTION OF THE INVENTION · Technical Field of the Invention The present invention relates to a driving circuit and a power supply method, and more particularly to a driving circuit, a controller and a method for supplying power to a plurality of light emitting diode light sources. [Prior Art] In a display system, a drive circuit is typically used to drive one or more of the light sources to provide illumination to the display panel. For example, in a liquid crystal (LCD) display system using a light-emitting diode (LED) backlight, an LED array is used to illuminate the liquid crystal screen. An LED array typically includes two or more LED strings, each of which includes a plurality of LEDs in series. For each LED string, the forward voltage required to achieve the desired light output may vary depending on the LED's wafer area, material, product variation, or temperature. Therefore, in order to produce a consistently bright light output, the forward voltage of each LED string should be adjusted so that the current flowing through each of the strings is substantially equal. Figures 1 and 2 show two conventional methods, respectively. 1 is a block diagram of a conventional LED driver circuit 100. The LED driving circuit 100 includes a DC/DC converter 1〇2 for converting the input DC voltage Vin into a desired adjusted voltage ν〇υτ, to the B string 108_b 108-2, ...108-供电 Power supply. The LED string 1〇8J, 1〇8-2, ... 108_N are respectively reduced in series with the linear LED current regulators 1〇6J, 1〇6 2, ..~i〇6 n . The selection circuit 104 receives the detection signals from the current detection resistors ", RSEN-2, ... RSENJ and generates a feedback signal. The DC current conversion β 102 adjusts the adjusted voltage according to the feedback signal. - Linear 0678-TW -CH Spec+Claim(sandra.t-20120130).d〇c 201228458 LED Current Regulator, 1〇6_2,...1〇6-N Operational Amplifier 110-1 '110-2,...ii〇j Compare The reference signal REF and the detection signals from the current detecting resistors RSEN-1, rSEN_2, ... RSENJ, and generate a control signal to adjust the impedance of the transistor, Q2, ... Qn in a linear mode. The LED driver circuit i〇Q linearly controls the transistors qi, Q2, ... (10) to adjust the LED current flowing through the LEd string, 108-2, ... 108 J, respectively. However, this method is not suitable for requiring relatively large LEDs. The system of current 'because it causes the transistor q Q2 (10) to generate a large amount of heat. Therefore, the power efficiency of the system is reduced due to heat/power consumption. Figure 2 is not another conventional LED driver circuit. 〇 , , 。 。 ' ' ' ' ' ' ' ' ' ' ' 每一 每一 每一 每一The stream conversion f 202_1 202-2, ... 2 〇 2_N phase is connected. Each DC/DC conversion benefit 202-1, 202_2, ... 202_N receives from the corresponding current detecting resistors pSE11, RSEN-2, ... RSENJ's feedback signal, and according to the corresponding ED current demand, respectively, adjust the output voltage · D," v - 2, ... N ° the disadvantage of this method - is, because each - LED string needs one A dedicated DC/DC converter, if the system contains many rates, the system cost will increase accordingly. SUMMARY OF THE INVENTION An object of the present invention is to provide a driving circuit for a plurality of light emitting diode light sources, including: - an energy converter, receiving - input voltage and , ', the light emitting body light source Provide - adjust the voltage; and a number of current balance controllers 'secret to the amount of change, the dragon is through the multiple 0678 TW-CH Spec +Claim (sandra.t-20120130).doc 201228458 received from the "h ^ bit a first reference signal of the drought and a maximum reference-second reference signal, and each of the plurality of currents is the target average level, and each of the plurality of currents is adjusted. The following is a detailed description of the embodiment of the present invention. Although the present invention is described in detail, it should be understood that this is not intended to limit the present invention. The present invention is intended to cover various modifications, adaptations and equivalents as defined by the scope of the invention as defined by the appended claims. In order to provide this The full understanding of the 'provides a great deal of detail. However, it will be understood by those of ordinary skill in the art that the present invention may be practiced without these specific details. In other examples, well known methods The procedures, elements, and circuits are not described in detail to facilitate the purpose of the present invention. Embodiments of the present invention provide a circuit and method for powering an LED light source. The drive circuit regulates the flow through the LED light source by controlling a switch in series with the LED light source. The current can be alternately turned on and off according to a drive signal. The duty cycle of the drive signal is determined based on a monitoring nickname indicating the current flowing through the LED source. More specifically, in one embodiment, the responsibility of the drive signal The period is determined by the error # indicating the difference between the average value of the monitoring signal and the first reference value. The amplitude of the driving signal is determined by the monitoring signal and the second 0678-TW-CH Spec+Claim (sandra, t-20120130). Doc 6 201228458 The difference between the reference values is determined. The first reference value determines the flow through the LED source, the target average current, the second reference Determine the maximum transient current flowing through the LED source. The average current flowing through the LED source is adjusted to be substantially the same as the target average current. The transient current flowing through each LED source can be controlled at a large transient current. In this way, it is advantageous that the drive circuit improves energy efficiency and does not require a plurality of specialized energy converters. Figure 3 is a block diagram of a LED drive circuit 300 in accordance with one embodiment of the present invention. 300 includes for multiple LEDs

The string provides a regulated voltage to the power converter (e.g., DC/DC converter 302). In the example shown in FIG. 3, three lED strings 308-1, 308_2, and 308_3 are displayed for convenience of explanation. However, the LED driver circuit 3 can include any number of LED strings. The LED driving circuit 300 further includes a plurality of switching regulators (such as a plurality of step-down switching regulators) 306-1, 306-2, and 306_3 coupled to the DC/DC converter 302 for respectively adjusting the LED strings 308. 1, the forward voltage of 308-2 and 308_3. The LED drive circuit 3A also includes a plurality of switch balance controllers 304J, 3〇4-2, and 3〇4 3 for controlling the buck switch regulators 306J, 3〇6-2, and 3〇6-3, respectively. _2 in the DC/DC converter 302 and the buck switching regulators 306", 3. There is a feedback selection circuit 312 between the three for adjusting the output voltage of the DC/DC converter 302. A plurality of current monitors gw 1, gw 2 and 310-3 are coupled to the LED strings 308-j, 3〇8-2 and 3〇8 3, respectively, to provide monitoring signals ISENj, ISEN-2 and ISEN~3, Used to indicate the LED current flowing through LED strings 308-1, 308-2, and 308-3. The DC/DC converter 302 receives the input voltage Vin and outputs the adjusted voltage MN. In the embodiment, each of the switching balance controllers is 0678-TW-CH Spec+Claim(sandra.t-20120130).do« 201228458

J 304_2 and 304-3 receive the same reference signal, which indicates the current value of each LED string 308_1, 308-2 and 30°8"; Each of the switch balance controllers 304_1, 3〇4__2, and 3〇4^ receives the respective current monitors from:

Trn \ lTu2^ ° 1 益304J, 304-2 and 304_3 respectively generate pulse modulation signals according to the reference signal REF and the corresponding measurement signals (eg pulse width modulation PWM-1' PWM-2, PWM-3' and use pulse modulation The variable signals pWM-1, 1, and PWM_3 respectively adjust the buck switching regulator plus ^卯^ and 3 f voltage drop. - j's switching balance controller Gangshan Gangli rewards respectively maiden 306J, 306-2 and 306- The voltage drop across 3. For each of the LEDs 308J, 308-2, and 308-3, an LED current flows through the LED string according to the forward voltage on the LED string. - The forward voltage of the LED string is proportional to the adjustment The difference between the voltage drop and the voltage drop across the switching regulator corresponding to the LED string. Therefore, the buck switching regulator 306 is adjusted by using the switching balance controller 304, 3〇4-2, and 3〇4-3, respectively. 3〇6_2 and 3(3), the forward voltages of the LED strings 308J, 308-2, and 308~3 can be adjusted accordingly. Therefore, the LE coffee, the -2, and the air coffee are both neat. In an embodiment The switch balance controllers 3〇4-b and 304-3 respectively adjust the voltage drop of the buck switching regulators 3〇6—丨, 3〇6; and 3〇6_3, so that each L The current of the ED string and the expected current value are _ "substantially equal to the expected current value" means that the LED string is electrically = = within the variation 'such that each LED string produces a desired light output with a brightness. 0678-TW -CH Spec+Claim(sandra.t-20120130).doc 8 201228458 Switch balance controllers 304J, 3〇4_2 and 3〇4 3 can also generate complex errors based on the monitoring signals ISENJ, iSEN-2, ISEN_3 and reference signal REF. Money. Each health error indicates a forward voltage, which corresponds to the LED string to generate the forward voltage to generate an electrical grab that is substantially equal to the expected current. The feedback selection circuit 312 receives the error signal and determines which LED string has the largest Forward voltage. The forward voltage required to produce the desired light output for each of the LED strings 308-1, 308-2, and 308_3' may vary. Here, "maximum forward voltage" refers to an embodiment. The maximum forward voltage among the forward voltages of each LED string when the coffee claims 307-1 308-2 and 308_3 produce a desired light output of uniform brightness. The feedback selection circuit 312 generates a feedback signal 3 (u, Indicates the flow of LEDs with the largest forward voltage As a result, in one embodiment, the DC/DC converter 302 adjusts the brightness according to the feedback signal 30! to meet the power requirements of the LED string having the largest forward and voltage. For example, DC/DC conversion The device 302 boosts the VQUT to increase the LED current flowing through the string having the largest forward voltage, or to decrease ν 〇υτ to reduce the LED current flowing through the LED string having the largest forward voltage. 4 is a circuit diagram of an LED drive circuit 4A having a common anode connection in accordance with an embodiment of the present invention. Figure 4 will be described in conjunction with Figure 3. Elements in Figure 4 that have the same number as the ® 3 have similar functions and will not be repeated here for the sake of brevity. In the example of Fig. 4, two LED strings 308-1, 308_2 and 308-3 are shown for convenience of explanation. However, LED drive circuit 400 can include any number of LED strings. The LED driving circuit 4 uses a plurality of switching regulators (such as a step-down switching regulator) according to the reference signal REF and a plurality of monitoring signals ISEN j, 0678-TW-CH Spec+Claim (sandra.t-2〇120130). Doc 9 201228458 ISEN—2, ISEN—3 to adjust the forward voltage of the LED strings 3〇8—i, 3〇8_2, and 3, respectively. The monitoring signals ISENJ, ISEN-2, and ISEN-3 are generated by a plurality of electric "κ, respectively, indicating which motor flows through which _", 3〇8-2 彳308_3. In the example of Figure 4, each current monitor includes a current monitoring resistor RSEN-i (i = i, 2, 3). In one embodiment, each buck switching regulator includes an inductor

Ci (i 1 2 3) and a switch Si (i = 1, 2 ' 3). The inductance is in series with the corresponding LED string 308" (i = 1, 2, 3). The diode Di is connected in parallel with (10) serially and in series with the inductor Li. The capacitor Ci is connected in parallel with the corresponding LED string 308-i. The switch Si is between the inductor Li and ground. Each buck switch modulator is controlled by a pulse modulation signal, such as a pulse width modulation signal TMU generated by a corresponding switch balance controller i (i = 1, 2, 3). M, 2, 3) controlled.

The LpD drive circuit 4A further includes a DC/DC converter 3〇2 to provide an adjusted voltage 'and a feedback selection circuit 312 to provide a feedback signal 301 to adjust the adjustment of the DC/DC converter 3〇2 output. The post voltage is used to meet the power requirements of the LED string with the largest forward voltage. The DC/DC converter 302 receives the input voltage vin and produces a regulated voltage VOUT. The switching balance controller 3〇4_i controls the conduction state of the switch Si with the pulse width modulation signal PWM_i (i = l, 2, 3). During the first period of time during which the switch Si is in the conducting state, the LED current flows through the LED string 308_i, the inductor Li, the switch Si, and the current monitoring resistor RSENj to ground. In one embodiment, the forward voltage of the LED string 308J is proportional to the difference between the regulated voltage VOUT and the voltage drop across the corresponding switching regulator. Here, the 0678-TW-CH Spec+Claim (sandra.t-20120130).doc 10 201228458 DC converter 302 supplies (10) the string gas 1 and charges the inductor L1. In the _ 308-1, the inter-inductor section '(10) current flows through the LED string U to discharge the LED string f to the D power. . In the second period of time, the 'inductance J 3〇^i - in the embodiment, the pulse width modulation signal PWM". In the iron L1, the polar body D i, the capacitance c i know that pg off c. becomes a step-down switching regulator. If: 'Close the structure of the current monitoring resistor rsen. ~ The voltage drop and pressure on the shoulder Si are equal to 1 times VOUT and D, and the forward electric signal PWM-i on the money 'Μ3〇8' (10)n . Since p is adjusted by adjusting the pulse width, it is adjusted accordingly. , ED _ 3 〇 8 - i on the forward voltage can look at the current value of the reference 2 3 〇 4" receiving instructions - the monitoring signal of the period please Γ : /: flow (four) D_" of the current seven test _ number Ϊ ( ΡΜ ( 2,3), and compare the reference signal REF and two to adjust the pulse width modulation signal PWM-1 work I month D, to make the LED current and the desired current, the switch balance control m hemp m ISEN i production 4 Error L · data / test signal REF and monitoring signal - - gamma s person (1 = 1 ' 2 ' 3). Error signal VEA i = solid: (10) string 308 corresponding to voltage 'requires the forward voltage to Producing a current that is substantially equal to the expected current value. In the embodiment, if VEA-i is larger, 'the corresponding (10) string _" requires a larger, forward voltage. The switching balance controller in Figure 4 will This is described in detail in Fig. 5. 0678-TW-CH Spec+Claim(sandra.t-20120130).doc 11 201228458 In the meantime, the feedback selection circuit 312 receives the error signal VEAJ from the switch + balance control θ 3G4 respectively. And judge ^ flow through the phase material 'which string has the largest smooth pressure. The feedback circuit / 12 also receives the current monitoring resistance lion, I The signal iiH circuit 312 generates a feedback signal 3〇1 according to the error signal 和" and/or the monitoring signal ISEMj, the feedback signal 3〇1 is large: the LED current of the (10) string of voltages. DC/DC; The signal 301 is used to adjust the power demand of the LED string of the adjusted voltage V() UT π302 forward voltage. In one embodiment, the power requirement of the LED string having the largest forward voltage is satisfied. The power demand of the LED string. Therefore, all the 'two can get enough power_ to generate light with uniform brightness. Figure 5 shows the switch balance controller 3〇4 in Figure 4, and the switch balance controller And the corresponding = connection relationship. Figure 5 will be described in conjunction with Figure 4. -, Figure: In 3 cases, the switch balance control _" includes an integrator for generating the variance 仏唬VEA-1, and for Comparing the error signal and the ramp signal RMP to generate a pulse width modulation signal, the comparator 502. The integrator includes a resistor 5〇8 coupled to the current monitoring resistor RSENj, an error amplifier 51〇, and a capacitor 5〇. 6. One end of the capacitor 506 is coupled to the error The difference amplifier 51A is connected between the comparator 5〇2 and the other end is connected to the resistor 508. The error amplification state 510 receives two inputs. The first input is the product of the reference signal pin and the pulse width modulation signal #, by the multiplier (10) 0678-TW-CHSpec+Claim(sandra.t-20120130).doc 12 201228458 Generated. The second input is from the current monitoring unit and number ISEN_i. The input signal of the error amplifier 51A is compared with the error signal number by the pulse width modulation signal PWM i ^ RMP to the duty cycle of the signal just - i. The pulse width c-width modulation buffer 504 is configured to control the corresponding buck switch to adjust the k through the mitigation state. In the embodiment, when the amplitude of VEA_i in the first time; is higher than the ramp signal RMp, the pulse number PWM_i is set to 1, and the switch Si is turned on. In the period of -expansion and "周婕^", when the amplitude of the error signal VEA_i is low = in the example 'in the second pulse width modulation signal PWMj is set to Q, switch & = ^ RMP ' The duty cycle D of the comparison error signal VEA i and the ramp width modulation signal just can be used: in the two-pulse embodiment, the pulse width modulation signal increases the duty cycle of the signal VEA_i. It decreases as the error signal vea i bit J decreases. At the same time, the forward voltage of the LED string is transmitted through the pulse-changing signal TMU (4). In the implementation, the pulse width modulation signal with a larger = period causes the LED string 3〇8j to have a larger forward voltage' while the pulse width modulation signal with a smaller duty cycle results in the LED string 308_.i having a higher Small forward voltage. In one embodiment, the feedback selection circuit 312 of Figure 4 receives VEA-1, VEA-2, VEA_3' and determines which LED string has the maximum forward voltage by comparing VEAj 'VEA-2 and VEA3. For example, if VEAJ <VEA-2 <VEA_3, then feedback selection circuit 312 determines that LED string 308-3 has the maximum forward voltage and is generated to indicate the LED string 3〇8 3 0678-TW-CH Spec+Claim(sandra .t-20120130).doc 13 201228458 LED current feedback signal 301 ° The DC/DC converter 302 in FIG. 4 receives the feedback signal 301 and adjusts the adjusted voltage ν〇υΤ to satisfy the LED string 308-3 electricity demand. The V〇UT can satisfy the power requirements of the LED string 308_1 and the LED string 308_2 as long as it can satisfy the power demand of the LED string 3〇8_3. Thus, all of the LED strings 308-1, 3〇8_2, and 308_3 can obtain sufficient power to produce a desired light output with consistent brightness. Figure 6 shows the relationship between LED current 6〇4 flowing through LED string 308J, inductor current 602, RSEN-i of inductor Li, and voltage 6 0 6 at node 514 between switches Si. Figure 6 will be described in conjunction with Figures 4 and 5. The DC/DC converter 302 supplies power to the LED string 308_i during the period in which the switch Si is turned on, and charges the inductor Li with the adjusted voltage VOUT. When the switch Si is turned "on" by PWM_i, the inductor current β〇2 flows through the switch si and the current monitoring resistor RSEN" to ground. When the switch Si is turned on, the electric salt current 602 gradually increases, and the voltage 606 on the node 514 increases. During the period of time when the switch S i is turned off, the inductor is discharged and the [ED string 308-i is supplied with power. Although the switch Si is turned off by PWM_i, the inductor current go? flows through the inductor 1^1, the diode Di, and the LED string 308". When the switch Si is turned off, the inductor current 602 gradually decreases. Since no current flows through the current monitoring resistor RSEN_i, the voltage 6〇6 at node 514 is reduced to 〇. In an embodiment, the capacitor axially coupled to the LED string 3G8J filters (filters) the inductor current, and produces a substantial (10) current 604' whose level is the average level of the inductor current 6〇2. Therefore, the LED ray of the LED string 308 i, * / (At Du & ^ current 604 can be adjusted towards the target power & in a consistent embodiment, when the switch si is turned on, node 514

The average impurity (4) on the reference signal REF voltage value / U 0678-TW-CH Spec + Claim (sandra.t-2012013〇), d〇c 14 201228458 (four) two (four) Γ according to the invention - implementation (four) with common cathode connection Then ◦ 电路 _. The components numbered in Fig. 7 and having the same number as in Fig. 4 have the class (4) Wei. For the sake of convenience, for the sake of convenience, H Hill does not display two LED strings 308J, 3〇8_2 Shoukou 308_3 in January. However, the LED drive circuit can include a number of strings. ', the LED driver circuit 4 in Figure 4 is similar, the coffee driver circuit · using a plurality of open_theaters (such as step-down on the _theater) according to the reference signal REF and a plurality of separate indications (10) string 3 〇 8 - i The current monitoring signals ISEN-1, ISEN_2, and 〜3 of 3〇8-2 and 3 are used to adjust the forward voltage of which series 308-1 308-2 and 308-3. Monitoring signal 丨娜", nwmg] current monitoring! | Produced. In the example of FIG. 7, the mother current monitor includes a current monitoring resistor RSENj (丨=1, 2 '3), a differential amplifier 7〇2_ soil (i=H 3), and a Resistor 706" (丨 = Bu 2, 3). The current monitoring resistor RSEN_i is connected in series with the corresponding LED string 308_i. The differential amplifier 7〇2_i is coupled between the current monitoring resistor RSENj and the switching balance controller 7〇4J^. The resistor 706-i is coupled between the error amplifier 7〇2j and the ground. In one embodiment, each buck switching regulator includes an inductor Li (i=l '2,3), a diode Di (i=1,2,3), and a capacitor (i=l, 2 ' 3) and one switch Si (i = 1, 2, 3). The inductor u is connected in series with the corresponding LED string 308-i (i = 1, 2, 3). The diode Di is connected in parallel with the LED string 308-i and the inductor Li connected in series therewith. The capacitor ci is connected in parallel with the corresponding LED string 308_i. The switch Si is coupled between the DC/DC converter 3〇2 and the inductor Li. Each buck switching regulator is controlled by a pulse modulation signal 0678-TW-CH Spec+Claim(sandra.t-20120I30).doc 15 201228458, for example by a corresponding switch balancing controller 7〇4j (i= 1, 2, 3) The generated pulse width modulation signal PWM_i (i = 1, 2, 3) is controlled. The LED driving circuit 700 further includes a DC/DC converter 3〇2 for providing the adjusted voltage, and a feedback selection circuit 312 for providing the feedback signal 301 for adjusting the adjustment generated by the DC/DC converter 3〇2. The voltage is met to meet the power requirements of the LED string with the largest forward voltage. In one embodiment, the LED current flows through the LED string 308_i to ground during the first time that the switch Si is in the conducting state. The forward voltage of LED string 308i is proportional to the difference between the regulated voltage νουτ and the corresponding voltage drop across the switching regulator. During this first time period, the DC/DC converter 302 supplies power to the LED string 308_i and simultaneously charges the inductor u with the adjusted voltage ν 〇υτ. During the second period of time when the switch Si is in the off state, the LED current flows through the LED string 308_i, the inductance Li and the diode Di. During this second period of time, the inductor Li is discharged to supply power to the LED string 308-i. Figure 8 shows an architectural schematic of the switching balance controller 7〇4_i of Figure 7, and the connection relationship of the switching balance controller 704-i with the corresponding LED string 308i. 8 is similar to FIG. 5 except that for the LED driving circuit 700 having the common cathode connection in FIG. 7, the differential amplifier i detects the voltage drop across the current monitoring resistor RSEN_i. A monitoring signal I sen i indicative of the LED current of the LED string 308_i can be generated via the resistor i. In one embodiment, resistor 706_i has the same resistance as current monitoring resistor RSENj. Figure 9 shows the relationship between the LED current 904 of the LED string 308_i, the inductor current 902 of the inductor Li, RSEN_i, and the voltage across the node 814 between the switches Si. Figure 9 will be described in conjunction with Figures 7 and 8. 0678-TW-CH Spec+Claim(sandra.t-20120130).doc 16 201228458 When the switch Si is turned on, the DC/DC converter 302 supplies power to the led string 308_i and charges the inductor Li with the adjusted voltage ν 〇υτ. When switch Si is turned on by PWM-i, inductor current 902 flows through LED string 308~i to ground. When switch Si is turned on, inductor current 902 gradually increases and voltage 906 at node 814 increases. When the switch Si is turned off, the inductor Li discharges and supplies power to the LED string 3〇8j. When the switch Si is turned off, the inductor current 902 flows through the inductor u, the LED string 308-i, and the diode Di. When the switch si is turned off, the inductor current 902 gradually decreases. Since no current flows through the current monitoring resistor RSEN_i at this time, the voltage 906 at node 814 rises to VOUT. In one embodiment, the capacitance Ci in parallel with the LED string 308_i filters the inductor current 902, thereby producing a substantially constant LED power 904' whose level is the average level of the inductor current 9〇2. Thus, the LED current 904 of the LED string 308-i can be adjusted toward the target current. In one embodiment, when switch Si is turned on, the average voltage value at node 814 is equal to the difference between the voltage of VOUT and the voltage of reference signal REF. Figure 10 is a flow diagram of a method of driving a plurality of light sources in accordance with one embodiment of the present invention. Although specific steps are disclosed in Figure 0, this step is merely for illustrative purposes. That is, the present invention can be used to perform the steps of the other, or the steps of the specific steps in Fig. 1. Figure 1 is a description of Figure 3 and Figure 4. '° σ In step 1002, a turn-in voltage is converted to a regulated voltage by a power converter (e.g., DC/DC converter 302). In step 1004, the adjusted voltages are applied to a plurality of light sources (eg, LED strings 308-; 1, 308-2, and 308-3) to generate flow through complex 0678-TW-CH Spec+Claim (sandra.t, respectively). -20120130).doc 201228458 Source current of several light sources. In step _, the forward voltages of the respective light sources are respectively adjusted by a plurality of switching regulators (e.g., a plurality of step-down switching regulators 3G6J, 3G6-2, and 3G6_3). In step 1008, a plurality of pulse modulation signals (e.g., pulse width modulation, money PWM), Ρ·_2, PWM_3 phase (4) are used to adjust the plurality of switching regulators. In one embodiment, the switch Si is controlled by a pulse modulation signal such that the first time period during which the switch is turned on, the regulated voltage is supplied to a corresponding light source, and the adjusted voltage is used to charge a corresponding inductor Li. . During the second period of time when the switch is turned off, the inductor u is discharged, and the light source is supplied through the inductor Li discharge. In step 1010, the duty cycle of the pulse modulation code PWM-i is adjusted according to the reference signal REF and the monitoring signal I sen i . In one embodiment, the monitor signal ISEN_i is generated by the current monitor 310_丨 to indicate the source current flowing through the corresponding source. Fig. 11 is a block diagram showing an LED driving circuit 11A according to an embodiment of the present invention. The LED drive circuit 11A includes a converter 11〇2 that receives an input voltage and outputs the adjusted voltage VOUT to a plurality of LED strings. The converter 1102 can be a DC/DC converter or an AC/DC converter, but is not limited to this. In the embodiment shown in Figure 11, there are three led strings 307-1, 308 2 and 308_3 as exemplifications, but the LED drive circuit 11A may include other numbers of LED strings. The LED drive circuit 11 further includes a plurality of switches si, %, and S3 (e.g., metal oxide semiconductor field effect transistors) connected to the LED strings 3, 8b, 308_2, and 308_3, respectively. - In addition, the LED driving circuit 11A includes a plurality of current balancing controllers U04J, 1104_2 and 11 connected to the converter 11〇2 phase 0678-TW-CH Spec+Claim(sandra.t-20120130).doc 18 201228458 4-3. The electric node balance controllers 1H) 4-1, 1104-2, and 1104-3 can be adjusted to flow through the led strings 308-1, 308-2, respectively, within a predetermined range = (eg, below a predetermined current level). And 308_3 current, and through the control switch magic, % and S3 to balance the current flowing through the led strings 307-1, 308-2 and 308-3. Further, the current balance controllers 1104-1, 1104-2, and u〇4^L receive the first reference signal indicating the target average level and the first reference Qianpeng indicating the maximum standard, and each corresponding (10) The series current is adjusted to the target average level, and each corresponding (10) string of I and current levels are adjusted to be within the maximum transient level. The feedback selection circuit 1112 connected between the conversion $1102 and the current balance controller (4) 1104-2 and H04-3 is based on the output of the current-sense converter HG2 of the flow thin (10) and the three currents. (for example, resistors Rsen_", Rsen2, and r ^i SI ^ S2 ^ S3 , ^^^^^ . ^ LED string 308 - Butong-2 and gas 3 current monitoring signals (4) Lions 2 and _3 In one embodiment, the monitoring signals, ISEN-2 and ISEN-3, respectively indicate that the forward voltage 308_i (.,|, 〇V3〇gi of the corresponding LED string can be calculated by the following equation: (3)

V308_i = VOUT - Vsi - VlSEN number where ' vsi is the forward voltage on switch si and νι_ is the voltage of the monitoring signal VlSEN_i. ° 0678-TW-CH Spcc+Claini(sandra.t-20120130).doc 19 201228458 The current balancing controllers ll〇4_l, 1104-2 and 1104_3 generate multiple drives b tiger DRVJ, DRV-2 and DRV-3 (eg , pulse signal) to control switches S1, S2 and S3 in series with LED strings 308_1, 308-2 and 308-3, respectively. The duty cycle of the drive signal DRV-i (e.g., 丨 = 1, 2, 3) is determined based on a corresponding monitor signal ISEN_i and the first reference signal REF1. More specifically, in an embodiment, the duty cycle of the drive signal DRVj is determined according to the average value of the corresponding monitor signal ISENj and the difference of the first reference "number REF1. Alternatively, the drive signal is The period is determined according to the average value of the difference between the corresponding monitoring signal ISEN_i and the first reference signal REF1. The amplitude of the driving signal DRV-i is determined according to the difference between the corresponding monitoring signal ISEN_i and the second reference signal REF2. During operation, the current balance controller 11〇4_i receives the first reference signal REn indicating the target average current Irefi and receives the corresponding monitor signal ISEN_i from the current sensor RSEN_i. The current balance controller 11〇4" is based on A reference signal REF1 and a monitor signal iSEN_i generate an error signal VEAC-1. More specifically, in one embodiment, the current balancing controller 1104_ι generates an error 彳 VEAC_i indicating the difference between the average of the reference signal REF1 and the monitoring signal ISENj. Alternatively, the current balance controller 1104_ι generates an error signal VEAC_i indicating the average of the difference between the reference signal REF1 and the monitor signal ISEN_j. In one embodiment, the error signal VEAC_i also indicates the amount of forward voltage of the respective LED string 308_i to produce a Led current having an average level substantially the same as the target average current IREF1. A corresponding drive signal DRV_i is generated based on the error signal VEAC_i ' current balancing controller ii 〇 4j to adjust the current flowing through the LED string 308 i . 0678-TW-CH Spec+Claim(sandra.t-20120130).doc 20 201228458 7 is a pulse modulation signal (for example, the pulse width modulation signal is in the 疋, the switch Si can be turned on or off alternately = the flow can be discontinuous Flow through LED string 1; electricity: quasi-utf equal to target current one. In a ^ example, 'error signal position' and reference signal _ !sen ^-1 ^tbf" ° 5 - comparison test signal REFl Small, so that the level of the error signal VEAC-i is high, so that the duty cycle is equal to 臓, and the opening of the eye can always be guaranteed to turn on. This way, the flow through the LED φ 308_i (four) can be kept continuous. Ii 〇 4_i receives a second reference signal REF2 indicating the maximum transient current Imax flowing through the string 308-i. The current balancing controller m4J controls the transient current Itran flowing through the LED _ 3G8_i to be within the maximum transient current i«ax, which prevents the LED string 3〇8-i from being overcurrent. A waveform of the converter 11A is shown in Fig. 12A - Fig. 12C. Figure ι2Α is the transient current iTRA (U through the LED string 308-1). Figure 12B shows the transient current flowing through the LED _ 308_2.

ItRAN_2 0 Figure 12C shows the transient current I ΤΈΑΝ _3 flowing through the LED string 308_3. If the error signal VEACL1 indicating the difference between the average value of the reference signal REF1 and the monitor signal ISEN1 is sufficiently large, the duty cycle of the drive signal DRV_1 is equal to 100%'. The transient current ImNJ flowing through the LED string 308_1 is continuous. Thus, the transient current flowing through the LED string 308_1 is equal to the average current flowing through the LED string 308-1. For the LED string 308_2, it is assumed that the error signal VEAC_2 is smaller than the error signal VEAC__1, and the duty of the monitoring signal ISEN-2 is 0678-TW-CH Spec+Claim(sandra.t-20120130).d〇c 21 201228458 cycle ratio monitoring signal ISen_1 small. Under the adjustment of the current balancing controller ii 〇 4_2, the transient current Itran_2 flowing through the LED string 308-2 is discontinuous and larger than the target average current IREF1. For the Led string 308-3, it is assumed that the error signal VEAC-3 is the smallest of the error signals VEAC_1, VEAC_2, and VEAC-3. Then, the duty cycle of the monitoring signal ISEN-3 is also the smallest one of the monitoring signals ISEN-1, lSEN_2, ISEN-3. Under the adjustment of the electric balance controller 1104-3, the temporary bear current ImN_3 flowing through the LED string 308 3 is the largest of the transient currents ItraN 3, Itran_3 and w3, but still smaller than the maximum transient current IMAX. Therefore, under the adjustment of the current balancing controllers 1104J, 1104-2, and 11〇4_3, the average current flowing through the LED strings 308J, 308_2, and 308-3 is substantially the same as the target average current 1 (^. The current balancing controller 〇 The adjustment of 4_i will be further discussed in Figure 13. Returning to Figure 11, in one embodiment, feedback selection circuit 1112 receives error signals VEAC_1, VEAC-2, and VEAC_3 and determines which LED string has the maximum turn-on voltage. In addition, the feedback selection circuit Ul2 determines which LED string has the maximum on-voltage according to the monitor signal ISEN-i from the current sensor RsEN_i. In one embodiment, the "maximum on-voltage" refers to the LED strings 308_1, 308. The maximum turn-on voltage of -2 and 308-3. In one embodiment, feedback feedback circuit 1112 generates a feedback signal 11 〇 1 indicative of the current of the LED string having the largest turn-on voltage. Thus, converter 1102 is based on a feedback letter No. 1101 adjusts VOUT to meet the energy requirements of the LED string with the maximum turn-on voltage. Accordingly, the energy requirements of the LED string with a higher turn-on voltage can also be satisfied. The connection of the current balance controller u〇4丨 in FIG. 11 is 0678-TW-CH Spec+Claim (sandra.t-20120130).doc 22 201228458 and the corresponding LED string 3G8". In one embodiment, =r^rilQ4J includes a second reference signal for receiving a first reference message indicating the target average reference signal, and a second reference signal for referring to the ^4 level: :, the balance controller (10) "adjusts the flow value to the target average level", and limits the flow through the (10) string transient level to within the maximum transient level w. The electric controller _i-step includes a sense The detector pin receives the monitoring signal of 曰d LED m. The current control 1 i 啸 监测 monitors the average value of ISEN—i and the first reference signal, and compares the monitoring signal ISEIU with the second reference signal·. The duty cycle of the current flowing through the LED string 3G8" is determined by the first reference signal REF1, and the amplitude of the current flowing through the led string 308" is determined by the second reference signal REF2. In the embodiment shown in Figure 13, the current balance control The device 11〇4j includes an integrator to generate an error signal VEAC_i, a comparator −13〇2 to The error signal VEAC_i and the ramp signal RMP generate an enable signal COMP-i, an error amplifier 1314 to generate a drive signal DRV-i to drive the switch Si. The integrator includes a resistor 1308 connected to the current sense resistor RsENi, an error amplifier 131〇, and a capacitor 13〇6. The electric valley 1306·-end is connected between the error amplifier 131〇 and the comparator 13〇2, and the other end is connected to the resistor 1308. The error amplifier 131 receives the average of the reference signal REF1 and the monitor signal ISEN_i, and generates an error signal VEAC_i based on the difference between the reference signal REF1 and the average value of the monitor signal ISEN_i. ° & 0678-TW-CH Spec+Claim(sandra.t-20120130).doc 23 201228458 The comparator 1302 compares the error signal VEAC_i with the ramp signal RMp to generate the enable signal C0MP_i. In the embodiment shown in Fig. 13, if the peak level of the ramp signal is lower than the error signal VEAQJ, the signal COMP_i remains at a constant level. Otherwise, the signal will include multiple pulses. #号COMP_i is used to enable and disable the error amplifier 1314. For example, in one embodiment, the error amplifier VEAC_i is greater than the ramp signal RMP' signal COMP_i having a logic high potential to enable the error amplifier 1314. In another embodiment, error signal amplifier 1314 is disabled when error signal VEACj is less than ramp signal RMP' signal COMP_i has a logic low potential. When the error amplifier 1314 is enabled by the signal COMP_i, the error amplifier 1314 compares the monitor signal ISEN_i with the second reference signal REF2 to generate a corresponding drive signal DRV_i. More specifically, if the error amplifier 1314 is disabled, the signal DRV-i turns off the switch Si, and no power & flows through the LED string 308_i. If error amplifier 1314 is enabled, signal DRV-i is controlled by the difference between reference signal REF2 and monitor signal ISEN_i. That is, the noble period of the signal DRV_i is determined by the signal c 〇 MP_i (e.g., the comparison value of the error signal VEAC_i and the ramp signal RMP). The amplitude of the signal DRV-i is determined by the difference between the reference signal REF2 and the monitor signal iSENj. In one embodiment, if the amplitude of the signal DRV_i is compared to the corresponding switch Si is fully turned on when turned on. If the amplitude of the signal (10) Vj is relatively low, the corresponding switch Si is linearly controlled when turned on. As a result, the error amplifier 1314 controls the average current flowing through the LED string 308-i to be substantially equal to the target average current Iavg, and the transient current Imw flowing through the LED string 308i is lower than the maximum transient current lMAX. For example, when the transient current Itran flowing through the LED 0678-TW-CH Spec+Claim(sandra.t-20120130).doc 24 201228458 string 308_ι increases, the amplitude of the signal DRV-i decreases, and then flows through the LED string 308. The transient current 17_ of i is reduced again. Therefore, the error signal VEAC_i indicating the difference between the average value of the monitor signal ISEN_i and the reference signal Rm is increased. Accordingly, the signal C 〇 MP - i indicating the noble period of the drive signal is increased. Thus, by reducing the amplitude of the signal service 乂i and increasing the duty cycle of the signal DRV-i, the average current of the LED string 3〇8-丨 remains substantially equal to the target average current 丨, and the transient current of the string 308_i does not exceed the maximum The transient current "μ. is advantageous in that the energy consumption of the switch is reduced. Thus, the thermal problem caused by the opening is avoided or reduced, and the energy efficiency of the string is advanced. More specifically 'in series with the LED string The switch has a continuous current transmission 'because the corresponding drive signal is deleted", the amplitude of the switch is relatively high, and the switch can be sufficiently turned on, thus having a small energy loss. A switch connected to the string has a discontinuous current, the transient current flowing through the switch increases, the on-time of the switch and the forward voltage drop of the switch decrease, such that the energy of the switch having a discontinuous current connected to the LED string The consumption will also be reduced. Figures 14A and 14B show waveforms 1400 associated with the architecture shown in Figure 13. 14A-14B will be described in conjunction with FIG. Fig. 14A shows waveforms of the error signal VEAC_i, the ramp signal RMp, the drive signal DRVj, the reference voltages REF1 and REF2, and the monitor signal ISENj. The transient level of the monitor signal ISENj is lower than the reference voltage REF2, and the average level of the monitor signal ISEN_i is substantially equal to the reference voltage refi. Figure 14B shows the error signal VEACj, the ramp signal 跗P, the drive signal DRV_i, the reference voltage REF1 and the service F2, and the monitoring signal 0678-TW-CH Spec+Claim(sandra.t-20120130).d〇〇25 201228458 In the embodiment shown by No. I SEN_ ISEli, No. DRV-VEAC_i, DRV-i ISEl ISEN, the signal is monitored and the signal is signaled. Moreover, the error signal is responsible for the signal VEACLi, and the transient period of the overtone signal is less than the transient level. The average level of the monitoring signal is (4) 2^2, and the monitoring signal m 1 Π is on the reference voltage REF1. Figure 15 is not a schematic diagram of the converter 1102 according to the structure of the present converter (10) for a DC/DC conversion. In the embodiment, the conversion Ray Π ΐ ΐ, the conversion includes an inductor 1502, a A pole body 1504, a control regulated voltage VOUT, a power switch 1508, a controller 153G, a rib generates a control signal 1522 of the control = Guan Cong, and a current sensor delete, a clock power _ simple current. The power switch can be a metal oxide semiconductor field effect transistor 'but not limited to this. In one embodiment, current sensor 1510 is a resistor. In another embodiment, control signal 1522 is a pulse width modulated signal (p-lane). During operation, when power switch 1508 is turned on, current flowing through inductor 1502, power switch 15 〇 8 and resistor 1510 charges inductor 15 〇 2 . When the power switch 1508 is turned off, the current flowing through the inductor 1502 and the diode 15〇4 charges the capacitor 1506. Thus, the adjusted voltage VOUT〇UT is thus adjusted. Controller 1530 includes an oscillator 1532, an accumulator 1534, a comparator 1536, and a buffer 1538. During operation, the accumulator 1534 accumulates the sensor signal from the current sensor 1510, 0678-TW-CH Spec+Claim (sandra.t-20120130).doc 26 201228458 and the ramp signal from the (4) device 1532, in turn Out-accumulate signal 1540. Comparative benefit 1536 compares the accumulated signal 154() with a feedback signal (10) indicating the LED_current having the largest forward voltage drop. The output of the comparator leg is provided to the power switch via buffer 1538. In this way, the control (4) 1522 quietly adjusts the voltage _ read to meet the energy requirements of the strings 308_2 and 308_3. Figure 7 is a diagram showing the driving circuit 诵 block @ according to the present invention. It has the same energy as the component of the phase in Fig. 11. The current balance control (4) also receives the corresponding dimming signal DIM". The dimming signal surface can be a pulse width modulation signal. The brightness of the string 3〇8ι can be controlled by the reference signal _ and just the dimming signal DIM-p, and when the dimming signal is set to the first level (4), for example, logic high potential, current balance The controller 1104J is enabled, and the drive signal DRV-i adjusts the current flowing through the LED string 308" according to the reference signal_ and just passing through the switch Si. When the dimming signal dim" is set to the second level (e.g., 'logic low potential'), the current balancing controller 1104 - is disabled, so that the switch Si is turned off and no current flows through the string 308". In one embodiment, the frequency of the dimming signal DIM_i is lower than the switching frequency of the switch S i . In addition, the LED driving circuit 1600 can synchronously drive the signal centering dimming signal DIM._i. For example, when the dimming money includes a positive edge to enable a corresponding current balance control ϋ 1104-i', the drive signal DRV-丨 also includes a positive edge to turn on the corresponding switch Si; when the dimming signal DIM-i includes a negative edge to disable The corresponding current balancing controller 11〇4_i, the drive signal DRV_丨 also includes a negative edge to turn off the corresponding switch S i . 0678-TW-CH Spec+Claiirt(sandra.t-20120130).doc 27 201228458

In addition, the operation of the signal D is performed. If any dimming signal (10) ^ ^ ^ device level, then the converter wrist, according to the feedback signal 11G] adjust the second: electric dust Cong. If all of the dimming signals (10) are after the ^: then the converter 1102' adjusts the voltage and does not adjust the adjusted voltage νουτ according to ^ #11 ο 1 . Sense - Figure 17 is a schematic diagram of the current balancing controller u 〇 4 - i of Figure 16 and its connection with the corresponding LED string 3G8J. Figure ~17 ′ is described in conjunction with Figure 13 and Figure 16. In the embodiment shown in Fig. 17, the flow balance control (four) ll 〇 4_i further includes a side light (four) pin to receive the dimming signal DIM_i. If the dimming signal DIM_i is at the first level, the current flowing through the LED string 308-i is determined by the first reference signal REF1 and the second reference signal REF2, and if the dimming signal DIM_i is at the second level, flowing through the LED string 308 The current of one i will be cut off. More specifically, the dimming signal DIM_i enables or disables the error amplifier 131A and the comparator 13〇2. If the dimming signal DIM_i is at the second level, the error amplifier 131A and the comparator 1302 are disabled and no current flows through the LED string 308_i. If the dimming signal DIM„i is at the first level, the error amplifier 1310 and the comparator 1302 are enabled. That is, the error amplifier 1310 compares the average of the reference signal REF1 with the monitor signal ISEN_i, and the comparator 1302 compares the ramp signal RMP. And the error signal VEAC_i, and the drive signal DRV_i adjusts the current flowing through the LED string 308_i through the switch Si. Further, the dimming signal DIMJ can control the ramp signal to synchronize the drive signal DRV_i with the dimming signal DIM_i. The synchronization process will be further in FIG. DESCRIPTION OF THE DRAWINGS Figure 18 is a diagram showing the waveform 1800 associated with the architecture 0678-TW-CH Spec+Claim(sandra.t-20120130).doc 28 201228458 shown in Figure 17 in accordance with an embodiment of the present invention. Dry (four) W is described in Figure 7. In Figure 18:: In the example, the 'dimming signal DIM_i is a pulse signal-dimming signal DOU transition from low to logic high, 钭 slope stretch (four) 仗 logic 觫πτμ The needle slope begins to increase with the ^^. When the dimming signal: such as - the first state 'current balance controller 1104', can be the root of (3) string 3G8-1. The error signal Xia-i 曰不> The test field _ and the monitoring signal signal ISEN-i transient level plate in the history of the φ factory difference ητκ · ^ ~ level is lower than the reference voltage REF2, and when Move 5:·'...: < During the time period of logic high, the monitoring signal_1 and the level of the flat sentence are substantially equal to the reference voltage. Μ Υ — - ° Zhou Guangyi tiger DIMJ from the first position to the second position drop: column: ': logic high potential conversion to logic low, ramp signal lower Φ: bit $. Correspondingly, the drive signal DRV-i turns off the switch Si, and no f current flows through the LED string j. Thus, the ramp signal is synchronized with the dimming signal DIM", and the drive signal and the dimming signal are also synchronized. Figure 19 is a block diagram showing the structure of the converter 1102 shown in Figure 16 of the present invention. The converter 11102 in the LED drive circuit 16A also includes an OR gate 1942 and a AND gate 1946 as compared to the converter 1102 in the LED drive circuit ιι. Or gate 1942 receives optical signals DIM_1-MM_3. In one embodiment, the pass gate 1942 and the gate 1946, when any of the dimming signals dimj is at the first level, the transition state 1102 adjusts ν〇υτ according to the feedback signal hoi, and when all the dimming signals DIM_1- DIM-3 is in the second position, except for the control of 0678-TW-CH Spec+Claim.(sandra.t-20120130).doc 29 201228458 is 1530, maintaining the regulated voltage VOUT. Figure 20 is a flow chart showing a method of powering a plurality of LED light sources in accordance with an embodiment of the present invention. Although the specific steps are described in Figure 2Q, the above steps are merely exemplary in nature, and the present invention is also applicable to other steps or variant embodiments of the steps in Figure 20. Figure 20 will be described in conjunction with Figure 16. In step 2002, an input voltage viN is converted to a regulated voltage V〇UT through a converter (e.g., DC/DC converter 11〇2'). And the adjusted voltage VOUT is applied to a plurality of LED sources (e.g., LED strings 308-1, 308-2, and 308_3) to generate a plurality of currents respectively flowing through the LED sources. In step 2004, a first reference signal REF1 indicating a target average level is received. 〆 In step 2006, a second spring signal REF2 indicating the maximum transient level is received. Less In step 2008, the average current of each current flowing through the LED source is adjusted to the target average level, and the transient level of each current flowing through the LED source is adjusted to be below the maximum transient level. Further, a plurality of pulse signals DRV-i are generated to adjust the currents flowing through the LED strings 308_1, 308 2, and 308-3, respectively. The duty cycle of the pulse signal DRV_i is determined based on the first reference signal REF1. The amplitude of the pulse signal DRV-i is determined according to the second parameter REF2. More specifically, the duty cycle of the pulse signal DRV_i is determined based on the comparison value of the error signal VEAC_i and the ramp signal RMP. In one embodiment, the error signal VEAC_i is determined by the average of the monitor signal iSENj and the difference of the first reference signal REF1. The amplitude of the pulse signal DRV 0678-TW-CHSpec+Claim(sandra.t-20120130).doc 30 201228458 is determined according to the difference between the second reference signal 2 and the monitoring signal iSEN-i. In one embodiment, the brightness of the LED string 308_i is further controlled by a dimming 彳5旎D[M-i. For example, when the dimming signal DIii is set to the first level (eg, logic high), the electric current flowing through the LED string 308-i is adjusted according to the reference signals REF1 and REp2, when the dimming signal]) IM_i By being again set to the second level (eg, logic low), the current flowing through the LED string 308_i is disabled. The above detailed description of the embodiments and the accompanying drawings are in the form of the embodiments of the present invention, and the invention may be variously modified, modified and substituted without departing from the spirit and scope of the invention as defined by the appended claims. It should be understood by those skilled in the art that the present invention may vary in form, structure, arrangement ratio, materials, elements, components, and other aspects in accordance with the specific environmental and operational requirements without departing from the scope of the invention. Therefore, the scope of the present invention is defined by the appended claims and their legal equivalents, and is not limited to the foregoing description. [Simplified description of the drawings] DETAILED DESCRIPTION OF THE INVENTION The technical methods of the present invention are described in detail to make the features and advantages of the present invention more apparent. 1 is a circuit diagram of a conventional LED driving circuit; FIG. 2 is not a circuit diagram of another conventional LED driving circuit; FIG. 3 is not a block of an LED driving circuit according to an embodiment of the present invention. FIG. 4 is a circuit diagram of an LED driving circuit according to an embodiment of the invention; FIG. 5 is a circuit diagram of an LED driving circuit according to an embodiment of the invention; FIG. 4 is a schematic diagram of the architecture of the switching balance controller and the connection relationship between the switching balance controller and the corresponding LEE string; FIG. 6 is a diagram showing the LED current, inductor current and current monitoring of FIG. 5 according to an embodiment of the invention. FIG. 7 is a circuit diagram of an LED driving circuit according to an embodiment of the invention; FIG. 8 is a diagram showing the architecture of the switching balancing controller of FIG. 7 according to an embodiment of the invention; FIG. 9 is a diagram showing a relationship between a LED current, an inductor current, and a voltage on a current detecting resistor of FIG. 8 according to an embodiment of the present invention; Figure 10 is a flow chart showing a method of driving a plurality of light sources according to an embodiment of the present invention; FIG. 11 is a block diagram showing an LED driving circuit according to an embodiment of the present invention; and FIGS. 12A to 12C are diagrams showing an embodiment of the present invention. In the LED driving circuit, the transient current waveform diagram of each LED string is shown; FIG. 13 is a schematic structural diagram of the current balancing controller in FIG. η according to an embodiment of the invention and its connection relationship with the corresponding LED string. 14A and 14B are diagrams showing the waveforms associated with the architecture shown in FIG. 13 in accordance with an embodiment of the present invention; and FIG. 15 is a diagram showing the transition 0678-TW-CH shown in FIG. 11 in accordance with an embodiment of the present invention. Spec+Claim(sandra.t-20120130).doc 32 201228458 Structure of the converter; Figure 16 is a block diagram of an LED driving circuit according to an embodiment of the present invention, and Figure 17 is a block diagram of an LED driving circuit according to an embodiment of the present invention. Figure 16 is a schematic diagram of the structure of the current balancing controller and its connection with the corresponding LED string; Figure 18 is a diagram showing the waveforms associated with the architecture shown in Figure 17 in accordance with an embodiment of the present invention; An embodiment of Figure 16 is shown Converter is a schematic structural diagram; FIG. 20 is a flowchart of a method according to a plurality of LED light sources of a power supply embodiment of the present invention. ' [Main component symbol description] 100 : LED drive circuit 102 : DC/DC converter 104 : Selection circuit 106_1, 106_2, ... 106-N : Linear LED current regulator 108 1 , 108 2, ... 108 N : LED string - - - 110 110 110 110 110 110 110 110 110 110 110 110 110 110 110 110 110 110 110 110 110 : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : Feedback signal 302: DC/DC converter 304_1, _ 304_2, 304_3: Switch balance controller 0678-TW-CH Spec+Claim(sandra.t-20120130).doc 33 201228458 306-1, 306-2 2 306- 3: buck switching regulators 308-1, 308_2, 308_3: LED string 310-1, 310-2, 31〇_3: current monitor 312: feedback selection circuit 502: comparator 504: buffer 506: capacitor 508: resistor 510: error amplifier 512: multiplier 514: node 602: inductor current 604: LED current 606: voltage 702J, 702_2, 702_3: differential amplifier 704_1, 704-2, 704-3: switching balance controller 706_1, 706_2, 706_3: Resistor 814: Node 902: Inductor Current 904: LED Current 906: Voltage 1000: Flowchart 10 02, 1004, 1006, 1008, 1010: Step 1100: LED drive circuit 1101: feedback signal 0678-TW-CH Spec+Claim (sandra.t-20120130).doc 34 201228458 1102, 1102': converter 1104_1, 1104_2 1104_3: Current balance controllers 1104_1', 1104_2', 1104_3': current balance controller 1112: feedback selection circuit 1302: comparator 1306: capacitor 1308: resistor 1310: error amplifier 1314: error amplifier 1400: waveform 1502: inductance 1504: Capacitor 1506: Diode 1508: Power Switch 1510: Current Sensor 1522: Control Signals 1530, 1530': Controller 1532: Oscillator 1534: Accumulator 1536: Comparator 1538: Buffer 1540: Accumulate Signal 1600: LED Driver Circuit 1800: Waveform 1942: or Gate 0678-TW-CH Spec+Claim (sandra.t-20120130).doc 35 201228458 1946: Gate 2000: Flowchart 2002, 2004, 2006, 2008: Step 0678- TW-CH Spec+Claim(sandra.t-20120130).doc 36

Claims (1)

201228458 VII. Patent Application Range···1· A driving circuit for a plurality of light-emitting two-in-one energy converters, comprising: a body light source providing a plurality of light-emitting diodes and a plurality of current balancing controllers Light-emitting diode light == converter's respective control signal and =- target average level of a first parameter of each of the multiple currents - two standard - second reference signal 'and target average ^ money Adjust to the level of each of the 妓 — — — — — — 暂 暂 暂 暂 暂 暂 暂 暂 暂 暂 暂 暂 暂 暂 暂 暂 暂 暂2. The drive circuit of claim 1, wherein if the dimming signal is at the first level, the plurality of current balancing controllers adjust the plurality according to the second reference signal and the second reference signal Electric /; L and wherein, if the dimming signal is at a second level, the plurality of current balancing controllers are disabled. 3. The driving circuit of claim 1 of the patent scope, further comprising: the U.S. Influenza detector' is coupled to the plurality of light emitting diode light sources to generate a plurality of monitoring signals indicative of the plurality of currents, respectively. 4. The drive circuit of claim 3, wherein the plurality of electrical μ balance controllers generate a plurality of drive signals to respectively control a plurality of switches in series with the plurality of light emitting diode light sources. 5. The driving circuit of claim 4, wherein the __ responsibility period of each of the plurality of driving signals is determined based on the first reference signal and a corresponding monitoring signal. 6. The driving circuit of claim 4, wherein an amplitude of each of the plurality of driving signals is based on the driving circuit of the fourth aspect of the invention A difference between the second reference signal and a corresponding monitor signal is determined. 7. The driving circuit of claim 4, wherein each of the plurality of current balancing controllers comprises a first coma amplifier based on the first reference signal and a corresponding monitoring signal A difference between the average values produces an error signal. 8. The driving circuit of claim 7, wherein each of the plurality of electrical balancing controllers further comprises a comparator coupled to the first error amplifier, comparing the error signal with a The ramp signal is used to generate a consistent energy signal. 9. The driving circuit of claim 8, wherein the current balancing controller further comprises a second error amplifier coupled to the comparator, and when the second error amplifier is enabled by the enabling signal, comparing The monitoring signal and the second reference signal generate a corresponding driving signal. 10. The driving circuit of claim 8, wherein when the dimming signal is at a first level, the first error amplifier compares an average value of the first reference signal with a corresponding monitoring signal, The comparator compares the error signal to the ramp signal; when the dimming signal is at a second level, the first error amplifier and the comparator are disabled. 11. The driving circuit of claim 4, wherein the plurality of driving signals are pulse width modulation (PWM) signals. 12. The driver circuit of claim 3, including: 0678-TW-CHSpec+Claim(sandra.t-20120130).doc 38 201228458 A feedback selection circuit coupled to the energy converter and the current Receiving the plurality of monitoring signals between the balance controllers and determining a light emitting diode light source having a maximum turn-on voltage from the plurality of light emitting diode light sources, the energy converter adjusting the adjustment voltage to satisfy the maximum The energy requirement of the light-emitting diode source of the turn-on voltage. 13. A controller for adjusting a current flowing through a light emitting diode source, comprising: a first reference pin receiving a first reference signal indicative of a target average level; a second reference pin, Receiving a second reference signal indicating a maximum transient level; and the controller adjusting an average current of the current to the target average level, and adjusting a transient level of the current to be lower than the Maximum transient level. 14. The controller of claim 13, wherein a duty cycle of the current is determined based on the first reference signal. 15. The controller of claim 13, wherein the amplitude of the current is determined according to the second reference k number. 16. The controller of claim 13, further comprising: a dimming control pin receiving a dimming signal, if the dimming signal is at a first level, the current is according to the first reference signal And determining the second reference signal, and wherein the current is cut off if the dimming signal is at a second level. 17. The controller of claim 13 of the patent scope further includes: 0678-TW-CH Spec+Claim(sandra.t-20120130).doc 39 201228458 A sensing pin receives a monitoring signal indicating the current, The controller compares an average of the monitored signal with the first reference signal and compares the monitored signal with the second reference signal. 18. A method of powering a plurality of light emitting diode sources, comprising: providing an adjustment voltage to the plurality of light emitting diode light sources, and generating a plurality of currents respectively flowing through the plurality of light emitting diode light sources; Receiving a first reference signal indicating a target average level; receiving a second reference signal indicating a maximum transient level; and adjusting an average current of each of the plurality of currents to the target average level And adjusting a transient level of each of the plurality of currents to be below the maximum transient level. 19. The method of claim 18, wherein a duty cycle of each of the plurality of currents is determined based on the first reference signal. 20. The method of claim 18, wherein the amplitude of each of the plurality of currents is determined based on the second reference signal. 0678-TW-CH Spec+Claim(sandra.t-20120130).doc 40