技术领域technical field
本发明涉及电源控制技术领域，尤其涉及一种低功耗的恒流控制电路和具有该低功耗的恒流控制电路的电视机。The invention relates to the technical field of power supply control, in particular to a low power consumption constant current control circuit and a television set with the low power consumption constant current control circuit.
背景技术Background technique
线性恒流调制电路是模拟集成电路中广泛使用的一种单元电路，在实际中有着广泛的应用。其中，在LED电视机的电源控制技术领域中，往往利用前端电路输出恒压、后端电路实现升压或降压恒流来实现对电视机主板和LED背光的供电。The linear constant current modulation circuit is a unit circuit widely used in analog integrated circuits, and has a wide range of applications in practice. Among them, in the field of power control technology of LED TVs, the front-end circuit is often used to output a constant voltage, and the back-end circuit is used to realize step-up or step-down constant current to realize power supply to the main board of the TV set and the LED backlight.
在对电视机部件进行整合过程中，电视机主板和背光灯条通常需要配套生产，而数量不同的背光LED灯条将需要线性恒流调制电路适应性输出不同的电压值。现有技术中采用一与电视机主板供电输出端连接的反馈回路，及时监控电视机主板供电输出端的电压变化。In the process of integrating TV components, TV motherboards and backlight strips usually need to be produced together, and different numbers of backlight LED strips will require linear constant current modulation circuits to adaptively output different voltage values. In the prior art, a feedback loop connected with the power supply output end of the main board of the TV set is adopted to monitor the voltage change of the power supply output end of the main board of the TV set in time.
如图1所示，是现有技术提供的一种线性恒流调制电路的原理图。当主板供电输出端的输出电压升高时，通过电阻RB135与电阻RB134分压后的电压信号接入到稳压管TL431的参考输入端R0中，并将该电压信号与稳压管TL431内部的基准参考电压(如2.5V)作比较，使得稳压管TL431阴阳极之间电压降低，进而光耦二极管PCB101A的电流变大，集电极与发射极之间的动态电阻变小，集电极与发射极之间的电压变低，随之供电电路中的内部变压器输出电压降低至设定的电压。因此，随着电阻RB134阻值的增大，LED供电输出端和主板供电输出端的输出电压减小，反之电压升高。As shown in FIG. 1 , it is a schematic diagram of a linear constant current modulation circuit provided by the prior art. When the output voltage of the power supply output terminal of the motherboard rises, the voltage signal divided by the resistor RB135 and the resistor RB134 is connected to the reference input terminal R0 of the voltage regulator tube TL431, and the voltage signal is compared with the internal reference of the voltage regulator tube TL431 Compared with the reference voltage (such as 2.5V), the voltage between the cathode and anode of the regulator tube TL431 decreases, and then the current of the optocoupler diode PCB101A becomes larger, the dynamic resistance between the collector and the emitter becomes smaller, and the collector and emitter The voltage between them becomes low, and the output voltage of the internal transformer in the power supply circuit drops to the set voltage. Therefore, as the resistance value of the resistor RB134 increases, the output voltages of the LED power supply output terminal and the motherboard power supply output terminal decrease, and vice versa, the voltage increases.
由于应用场合的不同，在实际生产过程中往往需要线性恒流电路输出不同的电压值，而现有技术为了满足不同场合需要，需要对硬件电路中的电阻RB135的阻值进行调整。因此，现有技术存在操作繁杂、精度低、功耗高和成本高的缺陷。此外，在实际应用中，背光LED灯条由多个LED串联而成，并通过MOS管或者三极管的开关管来控制以调整LED灯串的电流保持恒定。当线性恒流电路工作后，开关管两端电压会因LED灯串电压误差(一般单颗LED范围为2.8～3.4，由于串联多颗，所以LED灯串的电压范围的上限和下限的差值会比较大)，由于变压器的交调(一般范围为7％)而影响，电压越高功耗越大，这会造成器件的成本上升和电路效率的降低。另外，为了降低开关管的温度，一般开关管会由多个mos管或三极管并联使用，这就导致了成本的增加。Due to different application occasions, in the actual production process, the linear constant current circuit often needs to output different voltage values. However, in the prior art, the resistance value of the resistor RB135 in the hardware circuit needs to be adjusted in order to meet the needs of different occasions. Therefore, the prior art has the defects of complicated operation, low precision, high power consumption and high cost. In addition, in practical applications, the backlight LED light bar is composed of a plurality of LEDs in series, and is controlled by a switch tube of a MOS tube or a triode to adjust the current of the LED light string to keep constant. When the linear constant current circuit works, the voltage at both ends of the switching tube will be due to the voltage error of the LED light string (generally, the range of a single LED is 2.8 to 3.4, due to the series connection of multiple LED lights, the difference between the upper limit and the lower limit of the voltage range of the LED light string will be relatively large), due to the influence of the intermodulation of the transformer (the general range is 7%), the higher the voltage, the greater the power consumption, which will cause the cost of the device to increase and the circuit efficiency to decrease. In addition, in order to reduce the temperature of the switch tube, the switch tube is generally used in parallel with multiple mos tubes or triodes, which leads to an increase in cost.
发明内容Contents of the invention
本发明所要解决的技术问题是，提供一种低功耗的恒流控制电路，自适应地调整LED供电输出端的电压值和稳定供给电视机主板的电压值，无需对硬件电路进行调整。The technical problem to be solved by the present invention is to provide a constant current control circuit with low power consumption, which can adaptively adjust the voltage value of the LED power supply output terminal and the voltage value stably supplied to the main board of the TV without adjusting the hardware circuit.
为解决以上技术问题，本发明提供一种低功耗的恒流控制电路，包括：前端电源电路和后端线性恒流电路；In order to solve the above technical problems, the present invention provides a low power consumption constant current control circuit, including: a front-end power supply circuit and a rear-end linear constant current circuit;
所述前端电源电路包括供电电路和反馈调整电路；所述供电电路包括第一供电输出端、第二供电输出端和反馈控制端；所述反馈调整电路包括反馈输入端、控制信号输入端和反馈信号输出端；所述反馈输入端与所述第二供电输出端连接，所述反馈信号输出端与所述供电电路连接；所述反馈调整电路根据所述控制信号输入端的电压值，对所述反馈输入端接收的信号进行调整以向所述供电电路输出反馈信号，从而控制所述供电电路对所述第一供电输出端和所述第二供电输出端的电压值进行调整；The front-end power supply circuit includes a power supply circuit and a feedback adjustment circuit; the power supply circuit includes a first power supply output end, a second power supply output end, and a feedback control end; the feedback adjustment circuit includes a feedback input end, a control signal input end, and a feedback signal output terminal; the feedback input terminal is connected to the second power supply output terminal, and the feedback signal output terminal is connected to the power supply circuit; the feedback adjustment circuit controls the voltage value of the control signal input terminal according to the voltage value of the control signal input terminal The signal received by the feedback input terminal is adjusted to output a feedback signal to the power supply circuit, thereby controlling the power supply circuit to adjust the voltage values of the first power supply output terminal and the second power supply output terminal;
所述后端线性恒流电路设有一开关管，并通过所述开关管与待供电LED灯串的阴极连接，所述待供电LED灯串的阳极与所述第一供电输出端连接；所述后端线性恒流电路还设有一连接参考信号输入端以接入恒流参考电压，并根据所述恒流参考电压的大小控制所述开关管的导通、截止或导通程度，从而导通/断开所述后端线性恒流电路与所述待供电LED灯串的连接；The back-end linear constant current circuit is provided with a switch tube, which is connected to the cathode of the LED light string to be powered through the switch tube, and the anode of the LED light string to be powered is connected to the first power supply output end; the The back-end linear constant current circuit is also provided with a reference signal input terminal to connect to the constant current reference voltage, and controls the conduction, cutoff or conduction degree of the switch tube according to the magnitude of the constant current reference voltage, so as to conduct / Disconnect the connection between the back-end linear constant current circuit and the LED light string to be powered;
在所述开关管与所述待供电LED灯串连接处引出一路电压采集输出端以采集该连接处的电压，并根据采集结果调整所述控制信号输入端的电压值，从而进一步调整所述第一供电输出端、第二供电输出端的输出电压。Lead out a voltage acquisition output terminal at the connection between the switching tube and the LED light string to be powered to collect the voltage at the connection, and adjust the voltage value of the control signal input terminal according to the collection result, thereby further adjusting the first The output voltage of the power supply output terminal and the second power supply output terminal.
优选的，所述后端线性恒流调整电路包括比较调整电路和恒流控制电路；所述恒流控制电路包括所述开关管和开关电路；所述比较调整电路包括运算放大器，所述运算放大器的反相输入端连接所述参考信号输入端，正相输入端通过恒流检测电阻接地，所述运算放大器的输出端通过所述开关电路连接所述开关管的控制端；所述开关管的输入端与待供电LED灯串的阴极连接，所述待供电LED灯串的阳极与所述第一供电输出端连接；所述开关管的输出端通过所述恒流检测电阻接地Preferably, the back-end linear constant current adjustment circuit includes a comparison adjustment circuit and a constant current control circuit; the constant current control circuit includes the switch tube and a switch circuit; the comparison adjustment circuit includes an operational amplifier, and the operational amplifier The inverting input terminal of the operational amplifier is connected to the reference signal input terminal, the non-inverting input terminal is grounded through a constant current detection resistor, and the output terminal of the operational amplifier is connected to the control terminal of the switching tube through the switching circuit; The input end is connected to the cathode of the LED light string to be powered, and the anode of the LED light string to be powered is connected to the first power supply output end; the output end of the switching tube is grounded through the constant current detection resistor
优选的，当所述开关管为三极管时，所述三极管的集电极与所述待供电LED灯串的一端连接，发射极通过所述恒流检测电阻接地，基极通过所述开关电路与所述运算放大器的输出端连接；Preferably, when the switching tube is a triode, the collector of the triode is connected to one end of the LED light string to be powered, the emitter is grounded through the constant current detection resistor, and the base is connected to the LED light string through the switching circuit. The output terminal of the operational amplifier is connected;
当所述开关管为场效应晶体管时，所述场效应晶体管的漏极与所述待供电LED灯串的一端连接，源极通过所述恒流检测电阻接地，栅极通过所述开关电路与所述运算放大器的输出端。When the switch tube is a field effect transistor, the drain of the field effect transistor is connected to one end of the LED light string to be powered, the source is grounded through the constant current detection resistor, and the gate is connected to the ground through the switch circuit. output of the operational amplifier.
优选的，所述恒流检测电阻主要由电阻(RB6)、电阻(RB7)、电阻(RB8)与电阻(RB9)并联构成。Preferably, the constant current detection resistor is mainly composed of a resistor (RB6), a resistor (RB7), a resistor (RB8) and a resistor (RB9) connected in parallel.
优选的，所述运算放大器的正相输入端通过电阻(RB5)与所述恒流检测电阻连接，所述开关管的输出端连接至所述电阻(RB5)与所述恒流检测电阻的连接处。Preferably, the non-inverting input terminal of the operational amplifier is connected to the constant current detection resistor through a resistor (RB5), and the output terminal of the switch tube is connected to the connection between the resistor (RB5) and the constant current detection resistor place.
优选的，所述运算放大器的正相输入端还通过电容(CB5)接地。Preferably, the non-inverting input terminal of the operational amplifier is also grounded through a capacitor (CB5).
优选的，所述比较调整电路还包括一钳位二极管；所述钳位二极管的阴极接地；所述钳位二极管的阳极与所述开关管的输出端连接。Preferably, the comparison and adjustment circuit further includes a clamping diode; the cathode of the clamping diode is grounded; the anode of the clamping diode is connected to the output terminal of the switching tube.
优选的，仅当所述电压采集输出端采集到的该连接处的电压大于或等于预设的阈值时，才调整所述控制信号输入端的电压值，从而进一步调整所述第一供电输出端、第二供电输出端的输出电压，以使该连接处的电压小于预设的阈值。Preferably, only when the voltage at the connection collected by the voltage collection output terminal is greater than or equal to a preset threshold value, the voltage value of the control signal input terminal is adjusted, thereby further adjusting the first power supply output terminal, The output voltage of the second power supply output terminal, so that the voltage at the connection is less than a preset threshold.
优选的，还包括一控制主芯片；Preferably, it also includes a control main chip;
所述控制主芯片与所述控制信号输入端、所述参考信号输入端以及所述电压采集输出端分别连接；The control main chip is respectively connected to the control signal input terminal, the reference signal input terminal and the voltage acquisition output terminal;
所述控制主芯片根据所述电压采集输出端的电压变化，调节输出至所述控制信号输入端的信号大小，以控制所述前端电源电路的第一供电输出端、第二供电输出端的输出电压值；并通过所述参考信号输入端向所述后端线性恒流电路输入所述恒流参考电压。The control main chip adjusts the signal size output to the control signal input terminal according to the voltage change of the voltage acquisition output terminal, so as to control the output voltage values of the first power supply output terminal and the second power supply output terminal of the front-end power supply circuit; And input the constant current reference voltage to the back-end linear constant current circuit through the reference signal input terminal.
优选的，当所述控制主芯片检测到所述电压采集输出端与所述参考信号输入端的电压差值大于预设的阈值时，所述控制主芯片将输出至所述控制信号输入端的电压信号占空比减小。Preferably, when the control main chip detects that the voltage difference between the voltage acquisition output terminal and the reference signal input terminal is greater than a preset threshold, the control main chip outputs the voltage signal to the control signal input terminal The duty cycle is reduced.
优选的，所述控制主芯片包括模数转换器，用于将所述控制主芯片接入的电压信号转换为数字信号。Preferably, the control main chip includes an analog-to-digital converter for converting the voltage signal connected to the control main chip into a digital signal.
优选的，所述供电电路包括电源输入电路、开关电源电路、多路输出变压器、LED供电输出电路和主板供电输出电路；Preferably, the power supply circuit includes a power input circuit, a switching power supply circuit, a multi-output transformer, an LED power supply output circuit, and a motherboard power supply output circuit;
所述电源输入电路在所述开关电源电路的控制下将接入的电源信号传输至所述多路输出变压器；所述多路输出变压器包括主绕组和副绕组；所述主绕组将所述电源信号变压后传输至所述主板供电输出电路，并通过所述第二供电输出端进行输出；所述副绕组将所述电源信号同步变压后传输至所述LED供电输出电路，并通过所述第一供电输出端进行输出；所述主绕组与所述副绕组的线圈匝数比为1：N，N＞0。The power input circuit transmits the input power signal to the multi-output transformer under the control of the switching power supply circuit; the multi-output transformer includes a main winding and an auxiliary winding; the main winding connects the power supply After the signal is transformed, it is transmitted to the power supply output circuit of the main board, and is output through the second power supply output terminal; The first power supply output terminal for output; the coil turn ratio of the primary winding and the secondary winding is 1:N, N>0.
优选的，所述电压采集输出端通过降压电阻连接到所述开关管与所述待供电LED灯串的连接处。Preferably, the voltage collection output terminal is connected to the connection between the switching tube and the LED lamp string to be powered through a drop-down resistor.
优选的，所述反馈调整电路包括光耦反馈单元、稳压基准单元、电压采样单元和电压调整单元；Preferably, the feedback adjustment circuit includes an optocoupler feedback unit, a voltage regulation reference unit, a voltage sampling unit and a voltage adjustment unit;
所述光耦反馈单元包括光耦，所述光耦包括位于原边的发光二极管和位于副边的光信号转换器，所述发光二极管的信号输入端通过第一电阻连接所述反馈输入端；所述光信号转换器的信号输出端连接所述反馈信号输出端；The optocoupler feedback unit includes an optocoupler, the optocoupler includes a light emitting diode on the primary side and an optical signal converter on the secondary side, the signal input end of the light emitting diode is connected to the feedback input end through a first resistor; The signal output end of the optical signal converter is connected to the feedback signal output end;
所述电压采样单元包括连接于所述反馈输入端和地之间的串联的第四电阻和第五电阻；The voltage sampling unit includes a fourth resistor and a fifth resistor connected in series between the feedback input terminal and ground;
所述稳压基准单元包括稳压基准器以及连接于稳压基准器的参考输入端与阴极之间的稳压反馈电路；所述稳压基准器的参考输入端连接至第四电阻和第五电阻串联之间处，阳极接地，阴极连接所述发光二极管的信号输出端；The voltage-stabilizing reference unit includes a voltage-stabilizing reference and a voltage-stabilizing feedback circuit connected between the reference input of the voltage-stabilizing reference and the cathode; the reference input of the voltage-stabilizing reference is connected to the fourth resistor and the fifth resistor. Between the resistors in series, the anode is grounded, and the cathode is connected to the signal output terminal of the light emitting diode;
所述电压调整单元包括第六电阻，所述第六电阻的一端连接至所述第四电阻和第五电阻串联之间处，另一端连接所述控制信号输入端。The voltage adjustment unit includes a sixth resistor, one end of the sixth resistor is connected between the fourth resistor and the fifth resistor in series, and the other end is connected to the control signal input end.
优选的，所述稳压反馈电路包括第一电容和第三电阻；Preferably, the voltage stabilization feedback circuit includes a first capacitor and a third resistor;
所述第一电容的一端连接在所述稳压基准器的阴极上，另一端与第三电阻的一端串联；第三电阻的另一端连接在所述稳压基准器的参考输入端上。One end of the first capacitor is connected to the cathode of the voltage stabilizing reference device, and the other end is connected in series with one end of the third resistor; the other end of the third resistor is connected to the reference input terminal of the voltage stabilizing reference device.
优选的，所述稳压反馈电路包括第二电容；Preferably, the voltage stabilization feedback circuit includes a second capacitor;
所述第二电容的一端连接在所述稳压基准器的阴极上，另一端连接在所述稳压基准器的参考输入端上。One end of the second capacitor is connected to the cathode of the voltage stabilizing reference device, and the other end is connected to the reference input terminal of the voltage stabilizing reference device.
优选的，所述稳压反馈电路包括第一电容、第三电阻和第二电容；Preferably, the voltage stabilization feedback circuit includes a first capacitor, a third resistor and a second capacitor;
所述第一电容的一端连接在所述稳压基准器的阴极上，另一端与第三电阻的一端串联；第三电阻的另一端连接在所述稳压基准器的参考输入端上；One end of the first capacitor is connected to the cathode of the voltage stabilizing reference device, and the other end is connected in series with one end of the third resistor; the other end of the third resistor is connected to the reference input terminal of the voltage stabilizing reference device;
所述第二电容的一端连接在所述稳压基准器的阴极上，另一端连接在所述稳压基准器的参考输入端上。One end of the second capacitor is connected to the cathode of the voltage stabilizing reference device, and the other end is connected to the reference input terminal of the voltage stabilizing reference device.
优选的，所述控制信号输入端的电压值与所述供电电路的供电输出端的输出电压对应关系为：所述控制信号输入端的电压值每步进1％占空比时，所述第一供电输出端的输出电压变化0.01V，而所述第二供电输出端的输出电压变化0.1V。Preferably, the corresponding relationship between the voltage value of the control signal input terminal and the output voltage of the power supply output terminal of the power supply circuit is: when the voltage value of the control signal input terminal steps in a duty cycle of 1%, the first power supply output The output voltage of the terminal changes by 0.01V, while the output voltage of the second power supply output terminal changes by 0.1V.
优选的，所述控制信号输入端输入的为电压值范围是0V～3.3V的电压信号或PWM波，所述第一供电输出端的输出电压对应可调节为11.5V～12.5V，而所述第二供电输出端的输出电压自动适配。Preferably, the input of the control signal input terminal is a voltage signal or PWM wave with a voltage range of 0V-3.3V, the output voltage of the first power supply output terminal can be adjusted to 11.5V-12.5V, and the first The output voltage of the two power supply output terminals is automatically adapted.
本发明还提供了一种电视机，包括：电视机主板、背光LED灯串，以及如上所述的低功耗的恒流控制电路；所述低功耗的恒流控制电路与所述电视机主板和所述背光LED灯串分别连接，用于在打开所述电视机的电源时，根据所述背光LED灯串的工作电压，自适应调节供给所述电视机主板、所述背光LED灯串的电压信号。The present invention also provides a TV set, including: a TV main board, a backlight LED lamp string, and the above-mentioned low-power constant current control circuit; the low-power constant current control circuit and the TV set The main board and the backlight LED light string are respectively connected, and are used to adaptively adjust the voltage supplied to the TV main board and the backlight LED light string according to the working voltage of the backlight LED light string when the TV is powered on. voltage signal.
本发明提供的一种低功耗的恒流控制电路及电视机，设置有前端电源电路和后端线性恒流电路，利用前端电源电路调节两路输出的供电电压，并在前端电源电路中建立反馈调整电路，以及在反馈调整电路中设有控制信号输入端，以实现控制前端电源电路在第一供电输出端和第二供电输出端的电压；并通过设立后端线性恒流电路自动适应串联的LED背光灯数量的变化，可以根据LED背光灯串联后的电压值调整所述控制信号输入端的电压值，从而通过前端电源电路及其反馈调整电路控制所述第一供电输出端、第二供电输出端的输出电压，而第一供电输出端连接至LED背光灯进行供电，实现了与LED背光灯数量相适应的电压自动化调节，降低电路开关元件的功耗。A low power consumption constant current control circuit and a TV provided by the present invention are provided with a front-end power supply circuit and a rear-end linear constant-current circuit. A feedback adjustment circuit, and a control signal input terminal is provided in the feedback adjustment circuit to realize the control of the voltage of the front-end power supply circuit at the first power supply output terminal and the second power supply output terminal; The change in the number of LED backlights can adjust the voltage value of the control signal input terminal according to the voltage value of the LED backlights connected in series, so as to control the first power supply output terminal and the second power supply output through the front-end power supply circuit and its feedback adjustment circuit The output voltage of the terminal, and the first power supply output terminal is connected to the LED backlight for power supply, which realizes the automatic adjustment of the voltage corresponding to the number of LED backlights and reduces the power consumption of the circuit switching elements.
附图说明Description of drawings
图1是现有技术提供的一种线性恒流调制电路的原理图。FIG. 1 is a schematic diagram of a linear constant current modulation circuit provided in the prior art.
图2是本发明提供的低功耗的恒流控制电路的一个实施例的结构示意图。FIG. 2 is a schematic structural diagram of an embodiment of a low power consumption constant current control circuit provided by the present invention.
图3是本发明实施例提供的前端电源电路的一种可实现方式的原理图。Fig. 3 is a schematic diagram of a possible implementation of the front-end power supply circuit provided by the embodiment of the present invention.
图4是本发明实施例提供的前端电源电路的一种具体电路原理图。Fig. 4 is a specific circuit schematic diagram of the front-end power supply circuit provided by the embodiment of the present invention.
图5是本发明实施例提供的后端线性恒流电路的一种可实现方式的电路原理图。FIG. 5 is a schematic circuit diagram of a possible realization of the back-end linear constant current circuit provided by the embodiment of the present invention.
图6是本发明实施例提供的后端线性恒流电路的另一种可实现方式的电路原理图。FIG. 6 is a circuit schematic diagram of another possible implementation of the back-end linear constant current circuit provided by the embodiment of the present invention.
图7是本发明提供的低功耗的恒流控制电路的又一实施例的结构示意图。FIG. 7 is a schematic structural diagram of another embodiment of the low power consumption constant current control circuit provided by the present invention.
具体实施方式Detailed ways
下面将结合本发明实施例中的附图，对本发明实施例中的技术方案进行清楚、完整地描述。The following will clearly and completely describe the technical solutions in the embodiments of the present invention with reference to the drawings in the embodiments of the present invention.
参见图2，是本发明提供的低功耗的恒流控制电路的一个实施例的结构示意图。Referring to FIG. 2 , it is a schematic structural diagram of an embodiment of a low power consumption constant current control circuit provided by the present invention.
在本实施例中，所述的低功耗的恒流控制电路包括前端电源电路101和后端线性恒流电路103。In this embodiment, the low power consumption constant current control circuit includes a front-end power supply circuit 101 and a back-end linear constant current circuit 103 .
所述前端电源电路101包括供电电路1011、第一供电输出端OUT1、第二供电输出端OUT2和反馈调整电路1012；The front-end power supply circuit 101 includes a power supply circuit 1011, a first power supply output terminal OUT1, a second power supply output terminal OUT2 and a feedback adjustment circuit 1012;
其中，所述反馈调整电路1012包括反馈输入端A_in、控制信号输入端Cont和反馈信号输出端B_out；所述反馈输入端A_in与所述第二供电输出端OUT2连接，所述反馈信号输出端B_out与所述供电电路1011连接；所述反馈调整电路1012根据所述控制信号输入端Cont的电压值，向所述供电电路1011输出反馈信号，以控制所述供电电路1011对所述第一供电输出端OUT1和所述第二供电输出端OUT2的电压值进行调整。Wherein, the feedback adjustment circuit 1012 includes a feedback input terminal A_in, a control signal input terminal Cont and a feedback signal output terminal B_out; the feedback input terminal A_in is connected to the second power supply output terminal OUT2, and the feedback signal output terminal B_out Connected to the power supply circuit 1011; the feedback adjustment circuit 1012 outputs a feedback signal to the power supply circuit 1011 according to the voltage value of the control signal input terminal Cont, so as to control the power supply circuit 1011 to output the first power supply The voltage values of the terminal OUT1 and the second power supply output terminal OUT2 are adjusted.
所述后端线性恒流电路103设有一开关管QB1，并通过所述开关管QB1与所述待供电LED灯串的阴极LED-连接，所述待供电LED灯串的阳极LED+与所述第一供电输出端OUT1连接；所述后端线性恒流电路103设有一连接参考信号输入端PWM_REF，以接入恒流参考电压VREF，并根据所述恒流参考电压VREF的大小控制所述开关管QB1的导通、截止或导通程度，从而导通/断开所述后端线性恒流电路103与所述待供电LED灯串的连接。The back-end linear constant current circuit 103 is provided with a switch tube QB1, and is connected to the cathode LED- of the LED light string to be powered through the switch tube QB1, and the anode LED+ of the LED light string to be powered is connected to the first A power supply output terminal OUT1 is connected; the back-end linear constant current circuit 103 is provided with a connection reference signal input terminal PWM_REF to access the constant current reference voltage VREF, and control the switching tube according to the magnitude of the constant current reference voltage VREF The turn-on, cut-off or turn-on degree of QB1, so as to turn on/off the connection between the back-end linear constant current circuit 103 and the LED lamp string to be powered.
在所述开关管QB1与所述待供电LED灯串连接处P引出一路电压采集输出端(如图2中的输出端ADC_12V)，以根据所述待供电LED灯串的电压变化，调整所述控制信号输入端Cont的电压值，从而控制所述第一供电输出端OUT1、第二供电输出端OUT2的输出电压。At the connection between the switch tube QB1 and the LED light string to be powered, P leads a voltage acquisition output terminal (such as the output terminal ADC_12V in Figure 2), so as to adjust the voltage according to the voltage change of the LED light string to be powered. The voltage value of the signal input terminal Cont is controlled, thereby controlling the output voltages of the first power supply output terminal OUT1 and the second power supply output terminal OUT2.
参看图3，是本发明提供的前端电源电路的一种可实现方式的原理图。Referring to FIG. 3 , it is a schematic diagram of an implementable manner of the front-end power supply circuit provided by the present invention.
在一种可实现方式中，如图3所示，反馈调整电路1012可设有光耦PCB101、稳压器UB102及连接于所述第二供电输出端OUT和地之间的且主要由串联的电阻RB134和电阻RB135构成的电压采样电路。In one implementable manner, as shown in FIG. 3 , the feedback adjustment circuit 1012 can be provided with an optocoupler PCB101, a voltage regulator UB102, and a circuit connected between the second power supply output terminal OUT and the ground and mainly composed of a series circuit. The voltage sampling circuit composed of resistor RB134 and resistor RB135.
其中，所述光耦PCB101包括位于原边的发光二极管(即光耦PCB101的脚1和脚2的组件)和位于副边的光信号转换器(即光耦PCB101的脚3和脚4的组件)。Wherein, the optocoupler PCB101 includes light-emitting diodes on the primary side (i.e. the assembly of pin 1 and pin 2 of the optocoupler PCB101) and an optical signal converter located on the secondary side (i.e. the assembly of pin 3 and pin 4 of the optocoupler PCB101) ).
稳压器UB102将所述控制信号输入端输入的控制信号接入至光耦PCB101的位于原边的发光二极管；所述发光二极管将控制信号转换为光信号后传递至所述光耦PCB101的位于副边的光信号转换器；所述光信号转换器将光信号转换为电信号后输出至所述反馈信号输出端。The voltage regulator UB102 connects the control signal input by the control signal input terminal to the light-emitting diode on the primary side of the optocoupler PCB101; An optical signal converter on the secondary side; the optical signal converter converts the optical signal into an electrical signal and outputs it to the feedback signal output end.
其中，所述光耦PCB101包括位于原边的发光二级管和位于副边的光信号转换器，位于原边的发光二级管的输入端(脚1)通过电阻R131作为反馈输入端A_in与第二供电输出端OUT连接，且光耦PCB101的原边两端(脚1和脚2)与电阻R132并联；位于光耦PCB101的副边的光信号转换器的输出端(脚4)连接作为反馈信号输出端B_out与供电电路1011的反馈控制端feedback连接，光信号转换器的另一端(脚3)接地。需要说明的是，电阻RB132并非本实施例中的反馈电路中的必要电子元件。Wherein, the optocoupler PCB101 includes a light-emitting diode on the primary side and an optical signal converter on the secondary side, and the input terminal (pin 1) of the light-emitting diode on the primary side is used as the feedback input terminal A_in and The second power supply output terminal OUT is connected, and the two ends of the primary side of the optocoupler PCB101 (pin 1 and pin 2) are connected in parallel with the resistor R132; the output terminal (pin 4) of the optical signal converter located on the secondary side of the optocoupler PCB101 is connected as The feedback signal output terminal B_out is connected to the feedback control terminal feedback of the power supply circuit 1011 , and the other terminal (pin 3 ) of the optical signal converter is grounded. It should be noted that the resistor RB132 is not an essential electronic component in the feedback circuit in this embodiment.
稳压器UB102优选采用可调试精密稳压器，并内建2.5V(伏)的基准电压，具体地，可采用型号为TL431的稳压器进行实现。其中，所述可调试精密并联稳压器的阳极A接地，阴极K与所述光耦PCB101的位于原边的发光二极管连接；参考输入端R用于接入所述控制信号输入端Cont的控制信号。The voltage regulator UB102 is preferably an adjustable precision voltage regulator with a built-in reference voltage of 2.5V (volts). Specifically, a voltage regulator of the type TL431 can be used for implementation. Wherein, the anode A of the adjustable precision shunt voltage regulator is grounded, and the cathode K is connected to the light-emitting diode on the primary side of the optocoupler PCB101; the reference input terminal R is used to access the control signal input terminal Cont Signal.
如图3所示，稳压器UB102的阴极K与光耦PCB101原边的发光二级管2脚连接，稳压器UB102的阳极A接地；稳压基准器UB102的参考输入端(脚1)与阴极(脚3)之间设有稳压反馈电路；所述稳压基准器UB102的参考输入端参考输入端(脚1)连接至电阻RB134和电阻RB135串联之间处，稳压基准器UB102的阳极(脚2)接地，稳压基准器UB102的阴极(脚3)连接所述光耦PCB101的原边另一端(脚2)。As shown in Figure 3, the cathode K of the regulator UB102 is connected to pin 2 of the light-emitting diode on the primary side of the optocoupler PCB101, and the anode A of the regulator UB102 is grounded; the reference input terminal (pin 1) of the regulator UB102 A voltage stabilization feedback circuit is provided between the cathode (pin 3); the reference input terminal (pin 1) of the voltage stabilization reference device UB102 is connected to the place between the resistor RB134 and the resistor RB135 in series, and the voltage stabilization reference device UB102 The anode (pin 2) of the voltage regulator UB102 is connected to the other end of the primary side of the optocoupler PCB101 (pin 2).
在一种可实现的方式中，所述稳压反馈电路包括电容CB109和电阻RB133；所述电容CB109的一端连接在所述可调试精密并联稳压器的阴极K上，另一端与电阻RB133的一端串联；电阻RB133的另一端连接在所述可调试精密并联稳压器的参考输入端R上。In a practicable manner, the voltage stabilization feedback circuit includes a capacitor CB109 and a resistor RB133; one end of the capacitor CB109 is connected to the cathode K of the adjustable precision shunt regulator, and the other end is connected to the resistor RB133 One end is connected in series; the other end of the resistor RB133 is connected to the reference input end R of the adjustable precision shunt regulator.
在另一种可实现的方式中，所述稳压反馈电路包括电容CB110；所述电容CB110的一端连接在所述可调试精密并联稳压器的阴极K上，另一端连接在所述可调试精密并联稳压器的参考输入端R上。In another practicable manner, the voltage stabilization feedback circuit includes a capacitor CB110; one end of the capacitor CB110 is connected to the cathode K of the adjustable precision shunt regulator, and the other end is connected to the adjustable on the reference input R of the precision shunt regulator.
进一步地，本实施例可以将以上两种实现方式进行结合，以实现所述稳压反馈电路。即所述稳压反馈电路同时设有电容CB109、电阻RB133和电容CB110。Further, in this embodiment, the above two implementation manners may be combined to implement the voltage stabilization feedback circuit. That is, the voltage stabilizing feedback circuit is provided with a capacitor CB109, a resistor RB133 and a capacitor CB110 at the same time.
如图3所示，稳压器UB102的阴极K与光耦PCB101原边的发光二极管2脚连接，稳压器UB102的阳极A接地；电阻RB134的一端与稳压器UB102的参考输入端R连接，另一端接地；电容CB109的一端连接在所述可调试精密并联稳压器的阴极K上，另一端与电阻RB133的一端串联；电阻RB133的另一端连接在所述可调试精密并联稳压器的参考输入端R上；所述电容CB110的一端连接在所述可调试精密并联稳压器的阴极K上，另一端连接在所述可调试精密并联稳压器的参考输入端R上。As shown in Figure 3, the cathode K of the voltage regulator UB102 is connected to the light-emitting diode 2 pin of the primary side of the optocoupler PCB101, and the anode A of the voltage regulator UB102 is grounded; one end of the resistor RB134 is connected to the reference input terminal R of the voltage regulator UB102 , the other end is grounded; one end of the capacitor CB109 is connected to the cathode K of the adjustable precision shunt regulator, and the other end is connected in series with one end of the resistor RB133; the other end of the resistor RB133 is connected to the adjustable precision shunt regulator One end of the capacitor CB110 is connected to the cathode K of the adjustable precision shunt regulator, and the other end is connected to the reference input R of the adjustable precision shunt regulator.
进一步地，所述可调试精密并联稳压器的参考输入端R通过一分压器与所述控制信号输入端连接。在本实施例中，优选地，所述分压器为一电阻RB150。Further, the reference input terminal R of the adjustable precision shunt voltage regulator is connected to the control signal input terminal through a voltage divider. In this embodiment, preferably, the voltage divider is a resistor RB150.
反馈输入端A_in如图3所示，电容CB109一端与光耦PCB101的2脚连接，另一端与电阻RB133串联后与电阻RB150的一端连接，电阻RB150的另一端作为所述控制信号输入端Cont；电容CB110的一端与稳压器UB102的阴极K连接，另一端与稳压器UB102的参考输入端R连接；电阻RB135的一端与反馈输入端A_in连接，另一端与稳压器UB102的参考输入端R连接。由此，构成了反馈电路1012的一种具体的实施方式。The feedback input terminal A_in is shown in Figure 3, one end of the capacitor CB109 is connected to pin 2 of the optocoupler PCB101, the other end is connected in series with the resistor RB133 and then connected to one end of the resistor RB150, and the other end of the resistor RB150 is used as the control signal input terminal Cont; One end of the capacitor CB110 is connected to the cathode K of the voltage regulator UB102, and the other end is connected to the reference input terminal R of the voltage regulator UB102; one end of the resistor RB135 is connected to the feedback input terminal A_in, and the other end is connected to the reference input terminal of the voltage regulator UB102 R connection. Thus, a specific implementation manner of the feedback circuit 1012 is constituted.
图3所示的反馈调整电路1012与图1所示的现有反馈调整电路的主要改进点在于，在稳压器UB102的参考输入端R上增加一电阻RB150，同时通过控制信号输入端Cont引入一控制信号对稳压器UB102的阴极K的输出电压值进行自动化控制，从而可实现对供电电路1011及其输出电压的调节。The main improvement point between the feedback adjustment circuit 1012 shown in FIG. 3 and the existing feedback adjustment circuit shown in FIG. 1 is that a resistor RB150 is added to the reference input terminal R of the voltage regulator UB102, and at the same time, a resistor RB150 is introduced through the control signal input terminal Cont. A control signal automatically controls the output voltage value of the cathode K of the voltage regulator UB102, so as to realize the regulation of the power supply circuit 1011 and its output voltage.
参看图4，是本发明实施例提供的前端电源电路的一种具体电路原理图。Referring to FIG. 4 , it is a specific schematic circuit diagram of the front-end power supply circuit provided by the embodiment of the present invention.
所述供电电路1011包括电源输入电路11、开关电源电路12、多路输出变压器TB101、LED供电输出电路13和主板供电输出电路14；The power supply circuit 1011 includes a power input circuit 11, a switching power supply circuit 12, a multi-channel output transformer TB101, an LED power supply output circuit 13 and a motherboard power supply output circuit 14;
所述电源输入电路11在所述开关电源电路12的控制下将接入的电源信号传输至所述多路输出变压器TB101；如图4所示，所述多路输出变压器TB101包括主绕组和副绕组。其中，多路输出变压器TB101的9脚～11脚的线圈形成初级主绕组，多路输出变压器TB101的1脚～2脚的线圈形成次级主绕组；多路输出变压器TB101的7脚～8脚的线圈形成初级副绕组，多路输出变压器TB101的1脚～6脚的线圈形成次级副绕组(其中1、2脚之间的线圈共用)，且次级主副绕组之间可以共用部分绕组，也可以不共用。具体实施时，所述主绕组将所述电源信号变压后传输至所述主板供电输出电路14，并通过所述第二供电输出端OUT2进行输出；所述副绕组将所述电源信号同步变压后传输至所述LED供电输出电路13，并通过所述第一供电输出端OUT1进行输出；因此，图4中的多路输出变压器TB101具有两路输出电压，特别地，在电视机技术领域中，第一供电输出端OUT1优选为供给LED背光灯的供电输出端，第二供电输出端OUT2优选为供给电视机主板的供电输出端。The power input circuit 11 transmits the input power signal to the multi-output transformer TB101 under the control of the switching power supply circuit 12; as shown in FIG. 4, the multi-output transformer TB101 includes a main winding and a secondary winding. winding. Among them, the coils of pins 9 to 11 of the multi-output transformer TB101 form the primary main winding, and the coils of pins 1 to 2 of the multi-output transformer TB101 form the secondary main winding; the coils of pins 7 to 8 of the multi-output transformer TB101 The coils of the multi-channel output transformer TB101 form the primary secondary winding, and the coils of pins 1 to 6 of the multi-output transformer TB101 form the secondary secondary winding (the coils between pins 1 and 2 are shared), and the secondary primary and secondary windings can share part of the winding , or not shared. During specific implementation, the main winding transforms the power signal and transmits it to the mainboard power supply output circuit 14, and outputs it through the second power supply output terminal OUT2; the secondary winding synchronously transforms the power signal After the voltage is transmitted to the LED power supply output circuit 13, and output through the first power supply output terminal OUT1; therefore, the multi-output transformer TB101 in FIG. 4 has two output voltages, especially in the field of television technology Among them, the first power supply output terminal OUT1 is preferably the power supply output terminal for supplying the LED backlight, and the second power supply output terminal OUT2 is preferably the power supply output terminal for supplying the TV mainboard.
在本实施例中，多路输出变压器TB101每匝线圈的输出电压是相同的，当改变其中一路的输出电压，那么另一路的输出电压也将会同步跟随变化。例如，主绕组的线圈为2匝，输出电压为12V，即每匝线圈的输出电压为6V；假设副绕组的输出电压为120V，则副绕组的线圈匝数为20匝。而主绕组和副绕组的线圈匝数可根据实际应用场合进行调整，即所述主绕组与所述副绕组的线圈匝数比为1：N，N＞0，即当主绕组的输出电压为V1时，副绕组的输出电压为V2＝N*V1。In this embodiment, the output voltages of each coil of the multi-output transformer TB101 are the same, and when the output voltage of one of them is changed, the output voltage of the other will also change synchronously. For example, the coil of the main winding has 2 turns, and the output voltage is 12V, that is, the output voltage of each turn of the coil is 6V; assuming that the output voltage of the secondary winding is 120V, the number of turns of the secondary winding is 20 turns. The number of coil turns of the main winding and the auxiliary winding can be adjusted according to the actual application, that is, the ratio of the number of turns of the main winding to the auxiliary winding is 1:N, N>0, that is, when the output voltage of the main winding is V1 , the output voltage of the secondary winding is V2=N*V1.
需要说明的是，反馈调整电路1012的反馈输入端A_in可连接所述供电电路1011的第一供电输出端OUT1或第二供电输出端OUT2，并不影响本实施例的实施。It should be noted that the feedback input terminal A_in of the feedback adjustment circuit 1012 can be connected to the first power supply output terminal OUT1 or the second power supply output terminal OUT2 of the power supply circuit 1011, which does not affect the implementation of this embodiment.
本发明可通过线性调节反馈调整电路1012的控制信号输入端Cont接入的外部控制信号的大小，从而控制第一供电输出端OUT1或第二供电输出端OUT2的电压值。具体地，以所述反馈调整电路1012的反馈输入端A_in连接到所述供电电路1011的第二供电输出端OUT2为例，本实施例的基本工作原理主要为：The present invention can control the voltage value of the first power supply output terminal OUT1 or the second power supply output terminal OUT2 by linearly adjusting the magnitude of the external control signal connected to the control signal input terminal Cont of the feedback adjustment circuit 1012 . Specifically, taking the feedback input terminal A_in of the feedback adjustment circuit 1012 connected to the second power supply output terminal OUT2 of the power supply circuit 1011 as an example, the basic working principle of this embodiment is mainly as follows:
当供电电路1011的输出电压升高(第一供电输出端OUT1和第二供电输出端OUT2同时升高)时，控制信号输入端Cont的控制信号经过电阻RB135和电阻RB134、电阻RB150分压后的电压传输至稳压器UB102的参考输入端R，稳压器UB102将参考输入端R的信号值与其内部基准电压进行比较。当参考输入端R的信号值大于基准电压时，稳压器UB102阴阳极之间的电压降低，进而光耦PCB101A的电流增大，光耦PCB101B集电极与发射极之间动态电阻变小(光耦PCB101的集电极为光耦的4脚，发射极为光耦的3脚)，集电极与发射极之间的电压变低；随之连接的PWM(Pulse Width Modulation，脉冲宽度调制)控制芯片UB101的反馈脚COMP的电平变低，PWM控制芯片UB101输出占空比减小，从而使得多路输出变压器TB101的输出电压降低。反之，当参考输入端R的信号值小于基准电压时，可使得多路输出变压器TB101的输出电压升高。When the output voltage of the power supply circuit 1011 rises (the first power supply output terminal OUT1 and the second power supply output terminal OUT2 rise simultaneously), the control signal of the control signal input terminal Cont is divided by the resistor RB135, the resistor RB134, and the resistor RB150. The voltage is transmitted to the reference input R of the voltage regulator UB102, and the voltage regulator UB102 compares the signal value of the reference input R with its internal reference voltage. When the signal value of the reference input terminal R is greater than the reference voltage, the voltage between the cathode and anode of the voltage regulator UB102 decreases, and then the current of the optocoupler PCB101A increases, and the dynamic resistance between the collector and emitter of the optocoupler PCB101B becomes smaller (optical The collector of the coupler PCB101 is the 4-pin of the optocoupler, and the emitter is the 3-pin of the optocoupler), and the voltage between the collector and the emitter becomes lower; the PWM (Pulse Width Modulation, pulse width modulation) control chip UB101 connected therewith The level of the feedback pin COMP becomes low, and the output duty cycle of the PWM control chip UB101 decreases, thereby reducing the output voltage of the multi-output transformer TB101. On the contrary, when the signal value of the reference input terminal R is smaller than the reference voltage, the output voltage of the multi-output transformer TB101 can be increased.
因此，为调节稳压器UB102的参考输入端R接入的电压信号的大小从而控制变压器TB101的输出电压，本发明通过增加电阻RB150并在电阻RB150的一侧接入控制信号来实现这一目的。具体地，当需要调制第二供电输出端OUT2的输出电压，且稳压器UB102的内部基准电压为2.5V时，第二供电输出端的输出电压值计算公式为：Vout2＝基准电压*(1+R135/R134)，其中，基准电压优选为2.5V。优选地，可通过外部控制芯片输出一个PWM_12V信号至所述控制信号输入端Cont，经由电阻RB150将PWM_12V信号传输至电阻RB134与电阻RB135之间串联点(即稳压器UB102的参考输入端R)。Therefore, in order to adjust the magnitude of the voltage signal connected to the reference input terminal R of the voltage regulator UB102 and thereby control the output voltage of the transformer TB101, the present invention realizes this purpose by adding a resistor RB150 and connecting a control signal to one side of the resistor RB150 . Specifically, when the output voltage of the second power supply output terminal OUT2 needs to be modulated, and the internal reference voltage of the voltage regulator UB102 is 2.5V, the calculation formula of the output voltage value of the second power supply output terminal is: Vout2=reference voltage*(1+ R135/R134), wherein the reference voltage is preferably 2.5V. Preferably, an external control chip can output a PWM_12V signal to the control signal input terminal Cont, and transmit the PWM_12V signal to the series connection point between the resistor RB134 and the resistor RB135 (that is, the reference input terminal R of the regulator UB102) via the resistor RB150 .
具体实施时，控制信号输入端Cont的PWM_12V信号可可采用0-3.3V中的任意一个恒定电压值，或者，采用一定波形的PWM(Pulse Width Modulation，脉冲宽度调制)波。根据第二供电输出端的输出电压值计算公式：Vout2＝基准电压*(1+R135/R134)，当PWM_12V信号输出为3.3V时，第二供电输出端OUT2的输出电压为最小，因为控制信号输入端Cont的输入电压(3.3v)大于稳压器UB102的基准电压2.5V(电路稳定工作的时候1脚电压和基准电压几乎相等)，所以此时相当于是电阻RB150接到3.3V的电源上，也就是相当于将电阻RB150并联在了电阻RB135上，根据Vout1的电压公式可知，由于电阻RB135并联了电阻RB150，相当于电阻RB135的等效电阻减少，从而使输出电压Vout1降低。当PWM_12V信号输出为0V时，第二供电输出端OUT2的输出电压值为最大，因为当PWM_12V信号为0V时，相当于控制信号输入端Cont接地，电阻RB150与电阻RB134并联，根据输出电压公式，电阻RB134的等效电阻值变小，稳压器UB102的参考输入端R的电压变小，因此第二供电输出端OUT2的输出电压升高。During specific implementation, the PWM_12V signal at the control signal input terminal Cont can adopt any constant voltage value in the range of 0-3.3V, or use a certain waveform of PWM (Pulse Width Modulation, pulse width modulation) wave. According to the calculation formula of the output voltage value of the second power supply output terminal: Vout2=reference voltage*(1+R135/R134), when the PWM_12V signal output is 3.3V, the output voltage of the second power supply output terminal OUT2 is the minimum, because the control signal input The input voltage (3.3v) of the terminal Cont is greater than the reference voltage 2.5V of the voltage regulator UB102 (when the circuit works stably, the voltage of pin 1 is almost equal to the reference voltage), so at this time, it is equivalent to connecting the resistor RB150 to the 3.3V power supply. That is to say, the resistor RB150 is connected in parallel to the resistor RB135. According to the voltage formula of Vout1, since the resistor RB135 is connected in parallel with the resistor RB150, the equivalent resistance of the resistor RB135 is reduced, thereby reducing the output voltage Vout1. When the PWM_12V signal output is 0V, the output voltage value of the second power supply output terminal OUT2 is the maximum, because when the PWM_12V signal is 0V, it is equivalent to the control signal input terminal Cont being grounded, and the resistor RB150 is connected in parallel with the resistor RB134. According to the output voltage formula, The equivalent resistance value of the resistor RB134 becomes smaller, and the voltage of the reference input terminal R of the voltage regulator UB102 becomes smaller, so the output voltage of the second power supply output terminal OUT2 increases.
可见，通过线性调节反馈调整电路1012的控制信号输入端Cont输入的控制信号(例如上述的0V～3.3V的电压信号或PWM波)，可使得第二供电输出端OUT2的输出电压在实际常用电压范围11.5V～12.5V之间进行调节(Vout2_max＝12.5V，Vout2_min＝11.5V)，从而实现微调；同理，在多路输出变压器TB101的作用下，第一供电输出端OUT1的输出电压也将实现同步自动适配调节。It can be seen that by linearly adjusting the control signal input by the control signal input terminal Cont of the feedback adjustment circuit 1012 (for example, the above-mentioned 0V-3.3V voltage signal or PWM wave), the output voltage of the second power supply output terminal OUT2 can be kept at the actual common voltage Adjust between 11.5V～12.5V (Vout2_max=12.5V, Vout2_min=11.5V), so as to realize fine-tuning; similarly, under the action of multi-output transformer TB101, the output voltage of the first power supply output terminal OUT1 will also be Realize synchronous automatic adaptation adjustment.
在具体应用场合中，在产品待机情况下(供电电路输出减少)，可通过线性调节外部控制芯片向反馈调整电路1012的控制信号输入端Cont输入的控制信号为高电平(如3.3V)，从而可使供电电路1011的第二供电输出端OUT2输出的电压为最小输出电压，可以减少电视机主板的待机功耗。In a specific application, when the product is in standby (the output of the power supply circuit is reduced), the control signal input to the control signal input terminal Cont of the feedback adjustment circuit 1012 can be high level (such as 3.3V) by linearly adjusting the external control chip, Therefore, the voltage output by the second power supply output terminal OUT2 of the power supply circuit 1011 can be the minimum output voltage, which can reduce the standby power consumption of the TV main board.
此外，所述待供电LED灯串由多个LED灯串联而成，随着待供电的LED灯串的数量的增多，多个LED串联后所需要的供电电压不断增高，因此，要求第一供电输出端OUT1的输出电压能够自适应地响应LED的数量变化，自动调节其输出电压值。In addition, the LED light string to be powered is composed of multiple LED lights connected in series. With the increase of the number of LED light strings to be powered, the power supply voltage required by the series connection of multiple LEDs is constantly increasing. Therefore, it is required that the first power supply The output voltage of the output terminal OUT1 can adaptively respond to the change of the number of LEDs, and automatically adjust its output voltage value.
参看图5～6，是本发明提供的后端线性恒流电路的两种可实现方式的电路原理图。Referring to FIGS. 5-6 , they are circuit schematic diagrams of two implementable modes of the back-end linear constant current circuit provided by the present invention.
具体实施时，在所述后端线性恒流电路103中，所述比较调整电路1031包括运算放大器UB1A，所述运算放大器UB1A的反相输入端通过一电阻RB12与所述参考信号输入端PWM_REF连接；所述运算放大器UB1A的正相输入端连接有电流反馈电路，所述运算放大器UB1A的输出端通过一开关电路连接开关管QB1的控制端。具体地，如图5、6所示，该电流反馈电路包括由电阻RB6、电阻RB7、电阻RB8和电阻RB9并联组成的恒流检测电阻，还包括电阻RB5和电容CB5。其中，由电阻RB6、电阻RB7、电阻RB8与电阻RB9组成的恒流检测电阻的一端连接在电阻RB5的一端上，另一端接地；电阻RB5的另一端连接在所述运算放大器UB1A的正相输入端上。所述电容CB5的一端接地，另一端连接在所述运算放大器UB1A的正相输入端上。其中电阻RB5和电容CB5组成的电路可以对输入到运算放大器UB1A的正相输入端的信号进行滤波。During specific implementation, in the back-end linear constant current circuit 103, the comparison adjustment circuit 1031 includes an operational amplifier UB1A, and the inverting input terminal of the operational amplifier UB1A is connected to the reference signal input terminal PWM_REF through a resistor RB12 ; The non-inverting input terminal of the operational amplifier UB1A is connected to a current feedback circuit, and the output terminal of the operational amplifier UB1A is connected to the control terminal of the switch tube QB1 through a switch circuit. Specifically, as shown in FIGS. 5 and 6 , the current feedback circuit includes a constant current detection resistor composed of resistors RB6 , RB7 , RB8 and RB9 connected in parallel, and also includes a resistor RB5 and a capacitor CB5 . Wherein, one end of the constant current detecting resistor composed of resistor RB6, resistor RB7, resistor RB8 and resistor RB9 is connected to one end of the resistor RB5, and the other end is grounded; the other end of the resistor RB5 is connected to the positive phase input of the operational amplifier UB1A serve. One end of the capacitor CB5 is grounded, and the other end is connected to the non-inverting input end of the operational amplifier UB1A. The circuit composed of the resistor RB5 and the capacitor CB5 can filter the signal input to the non-inverting input terminal of the operational amplifier UB1A.
优选的，所述运算放大器UB1A的正相输入端还连接有一钳位二极管DB1，以保护所述比较调整电路1031的正常工作。Preferably, the non-inverting input terminal of the operational amplifier UB1A is further connected with a clamping diode DB1 to protect the normal operation of the comparison and adjustment circuit 1031 .
在所述后端线性恒流电路103中，所述恒流控制电路1032还包括开关电路和开关管QB1。开关管QB1可以为三极管或者MOS(Metal-Oxid-Semiconductor，金属氧化物半导体)场效应晶体管，简称MOS管或场效应晶体管。其中，开关管QB1的导通/截止以及导通程度状态跟其自身的物理特性相关联。例如，当开关管QB1为三极管时，根据三极管的伏安特性曲线，存在着饱和区、放大区和截止区，分别对三极管的发射极与集电极之间的电压信号产生不同的影响，如当三极管工作在饱和区时，三极管的发射极与集电极之间相当于短路(导通状态)。In the back-end linear constant current circuit 103, the constant current control circuit 1032 further includes a switch circuit and a switch tube QB1. The switch tube QB1 may be a triode or a MOS (Metal-Oxid-Semiconductor, Metal-Oxid-Semiconductor) field effect transistor, referred to as a MOS tube or a field effect transistor. Wherein, the on/off and the state of the degree of conduction of the switch tube QB1 are related to its own physical characteristics. For example, when the switch tube QB1 is a triode, according to the volt-ampere characteristic curve of the triode, there are saturation regions, amplification regions and cut-off regions, which respectively have different effects on the voltage signal between the emitter and collector of the triode, such as when When the triode works in the saturation region, the emitter and collector of the triode are equivalent to a short circuit (conduction state).
在本实施例中，如图5所示，当所述开关管QB1为三极管时，所述恒流控制电路1032通过所述三极管的集电极与所述待供电LED灯串的一端(LED-)连接；所述三极管的发射极与所述钳位二极管DB1的阳极连接，所述三极管的基极通过所述开关电路与所述运算放大器UB1A的输出端连接；如图6所示，当所述开关管QB1为场效应晶体管时，所述恒流控制电路1032通过所述场效应晶体管的漏极与所述待供电LED灯串的一端(LED-)连接；所述场效应晶体管的源极与所述钳位二极管DB1的阳极连接，所述场效应晶体管的栅极通过所述开关电路与所述运算放大器UB1A的输出端。In this embodiment, as shown in FIG. 5, when the switching tube QB1 is a triode, the constant current control circuit 1032 connects the collector of the triode to one end (LED-) of the LED lamp string to be powered. connected; the emitter of the triode is connected with the anode of the clamping diode DB1, and the base of the triode is connected with the output terminal of the operational amplifier UB1A through the switch circuit; as shown in Figure 6, when the When the switching tube QB1 is a field effect transistor, the constant current control circuit 1032 is connected to one end (LED-) of the LED lamp string to be powered through the drain of the field effect transistor; the source of the field effect transistor is connected to The anode of the clamping diode DB1 is connected, and the gate of the field effect transistor is connected to the output terminal of the operational amplifier UB1A through the switch circuit.
具体实施时，钳位二极管DB1的阴极接地，阳极通过电阻RB5连接在运算放大器UB1A的正相输入端。在后端线性恒流电路103启动后，经过运算放大器UB1A的调整，其正相输入端所连接恒流检测电阻所分得的电压值与其反向输入接入的恒流参考电压VREF相等，则当恒流参考电压VREF高于钳位二极管DB1的导通电压值(约0.7V)时，钳位二极管DB1将会导通接地，即由电阻RB6、电阻RB7、电阻RB8和电阻RB9并联组成的恒流检测电阻两端的电压值被钳位二极管DB1所限制，因此，钳位二极管DB1起到了一定的保护作用。During specific implementation, the cathode of the clamping diode DB1 is grounded, and the anode is connected to the non-inverting input terminal of the operational amplifier UB1A through the resistor RB5. After the back-end linear constant current circuit 103 is started, after adjustment of the operational amplifier UB1A, the voltage value obtained by the constant current detection resistor connected to its positive phase input terminal is equal to the constant current reference voltage VREF connected to its negative input terminal, Then when the constant current reference voltage VREF is higher than the conduction voltage value of the clamp diode DB1 (about 0.7V), the clamp diode DB1 will be turned on and grounded, that is, the resistance RB6, the resistance RB7, the resistance RB8 and the resistance RB9 are connected in parallel The voltage value at both ends of the composed constant current detection resistor is limited by the clamping diode DB1, therefore, the clamping diode DB1 plays a certain protective role.
并且，由于开关管QB1的发射极(开关管QB1为三极管)或源极(开关管QB1为MOS管)与钳位二极管DB1的阳极连接，因此流通开关管QB1的恒流值可以通过以下公式计算：In addition, since the emitter of the switching tube QB1 (the switching tube QB1 is a triode) or the source (the switching tube QB1 is a MOS tube) is connected to the anode of the clamping diode DB1, the constant current value of the switching tube QB1 can be calculated by the following formula :
当恒流参考电压VREF高于钳位二极管DB1的导通电压值时，流通开关管QB1的恒流信号为I恒流＝DB1的导通电压值/恒流检测电阻的阻值；当恒流参考电压VREF低于钳位二极管DB1的导通电压值时，流通开关管QB1的恒流信号为I恒流＝恒流参考电压VREF/恒流检测电阻的阻值。通常，钳位二极管DB1的导通电压值为0.7V，恒流检测电阻的阻值为电阻RB6、电阻RB7、电阻RB8和电阻RB9并联后的总阻值。When the constant current reference voltage VREF is higher than the conduction voltage value of the clamping diode DB1, the constant current signal flowing through the switch tube QB1 is Iconstant current =the conduction voltage value of DB1/the resistance value of the constant current detection resistor; when the constant current When the current reference voltage VREF is lower than the conduction voltage value of the clamping diode DB1, the constant current signal flowing through the switch tube QB1 is Iconstant current = constant current reference voltage VREF / resistance value of the constant current detection resistor. Usually, the conduction voltage of the clamping diode DB1 is 0.7V, and the resistance of the constant current detection resistor is the total resistance of the resistors RB6, RB7, RB8 and RB9 connected in parallel.
在本实施例中，第一供电输出端连接到LED灯串的正极LED+，通过开关管QB1的恒流控制，再串接恒流检测电阻(电阻RB6、电阻RB7、电阻RB8和电阻RB9的并联电阻)到地，恒流检测电阻将LED灯串的电流大小转换成电压信号接入到运算放大器UB1A与恒流参考电压VREF(由外部主芯片进行控制，或者接入固定电压，若为固定电压则输出的恒流值I恒流则为固定值，不能进行恒流大小的调节)进行比较和放大，从而控制开关管QB1调整LED灯串的电流保持恒定。In this embodiment, the first power supply output terminal is connected to the positive pole LED+ of the LED lamp string, and is controlled by the constant current of the switch tube QB1, and then connected in series with the constant current detection resistor (parallel connection of resistor RB6, resistor RB7, resistor RB8 and resistor RB9) Resistor) to ground, the constant current detection resistor converts the current of the LED light string into a voltage signal, which is connected to the operational amplifier UB1A and the constant current reference voltage VREF (controlled by an external main chip, or connected to a fixed voltage, if it is a fixed The voltage then outputs the constant current value I(constant current then is a fixed value, and the adjustment of the constant current size cannot be carried out) to compare and amplify, thereby controlling the switching tube QB1 to adjust the current of the LED light string to keep constant.
具体实施时，LED灯串一般会串联多颗LED灯，其中单颗LED的工作电压一般为2.8V～3.4V，多颗LED灯串联后的工作电压将相应增大。以开关管QB1为MOS管为例，开关管QB1的漏极与源极之间的电压VDS＝VOUT1—LED灯串工作电压—恒流参考电压VREF。因此，后端线性恒流电路103进入工作状态后，开关管QB1的漏极与源极之间的电压VDS将会受到LED灯串的工作电压大小的影响，此外还可能受到多路输出变压器TB101的交叉调制(一般范围为7％)的影响。In practice, the LED light string generally connects multiple LED lights in series, and the working voltage of a single LED is generally 2.8V to 3.4V, and the working voltage of multiple LED lights in series will increase accordingly. Taking the switch tube QB1 as a MOS tube as an example, the voltage between the drain and the source of the switch tube QB1 is VDS =VOUT1 —the working voltage of the LED light string—the constant current reference voltage VREF . Therefore, after the back-end linear constant current circuit 103 enters the working state, the voltage VDS between the drain and the source of the switching tube QB1 will be affected by the working voltage of the LED light string, and may also be affected by the multi-output transformer. Effect of TB101's intermodulation (7% typical range).
在现有技术中，随着LED灯串电压的变化，开关管QB1的漏源电压VDS电压也同步发生变化，开关管QB1的这部分功率(VDS*恒流值I恒流)将会转换成热量的形式散发出来，VDS电压越大，开关管QB1的功耗越大，温度越高。因此功耗过大的开关管QB1会降低电源效率并且导致开关管QB1过热而容易损坏。为了降低开关管QB1的温度，可以采用多个MOS管或三极管并联作为开关管QB1使用，但这一技术方案导致了成本的增加。为此，本实施例对后端线性恒流电路103作出进一步的改进。In the prior art, as the voltage of the LED light string changes, the drain-source voltage VDS voltage of the switch tube QB1 also changes synchronously, and this part of the power (VDS * constant current value Iconstant current ) of the switch tube QB1 will be Converted into heat and dissipated, the greater the VDS voltage, the greater the power consumption of the switch tube QB1, and the higher the temperature. Therefore, the switching tube QB1 with excessive power consumption will reduce the power supply efficiency and cause the switching tube QB1 to overheat and be easily damaged. In order to reduce the temperature of the switch tube QB1, multiple MOS tubes or triodes can be used in parallel as the switch tube QB1, but this technical solution leads to an increase in cost. For this reason, this embodiment makes further improvements to the back-end linear constant current circuit 103 .
参见图4～图6，本实施例通过在所述恒流控制电路1032与所述待供电LED灯串连接处P引出一路电压采集输出端ADC_12V，以实时检测待供电LED灯串的电压变化，为电压采集输出端ADC_12V与参考信号输入端PWM_REF之间的压降设定一个阈值，或者，为电压采集输出端ADC_12V的输出电压设定一个恒定值(参考信号输入端PWM_REF的电压VREF一般较小)，当电压采集输出端ADC_12V与参考信号输入端PWM_REF之间的压降大于所述阈值，或者电压采集输出端ADC_12V的输出电压大于所述恒定值时，通过调整前端电源电路101中的控制信号输入端Cont的控制信号PWM_12V，控制光耦PCB101将LED灯串的工作电压的变化情况(即第一供电输出端OUT1的电压变化情况)反馈到PWM控制芯片UB101，PWM控制芯片UB101控制开关管QB101改变占空比，从而使得电压采集输出端ADC_12V的电压值减去参考信号输入端PWM_REF的电压值等于或接近预设的所述阈值(或者电压采集输出端ADC_12V的电压值等于或接近所述恒定值)。例如，设定电压采集输出端ADC_12V的输出电压的恒定值为2V，当启动电路时ADC电压从0V开始线性爬升到2V后，停止PWM_12V变化；工作后因第一供电输出端OUT1的负载变化，变压器耦合到的电压就会上升，此时电压就会大于2V，那么ADC检测大于2V后，再次调节PWM_12V占空比，直到ADC电压降回2V，从而使开关管QB101两端电压会稳定在一个2V左右的电压。因此，本实施例可以通过控制信号输入端Cont的控制信号PWM_12V，限定电压采集输出端ADC_12V与参考信号输入端PWM_REF之间的压降，从而减小开关管QB1的漏源电压VDS受到LED灯串的电压变化的影响，降低开关管QB1的功耗和保证了电源效率。Referring to Fig. 4 to Fig. 6, in this embodiment, a voltage acquisition output terminal ADC_12V is drawn at the connection point P between the constant current control circuit 1032 and the LED light string to be powered, so as to detect the voltage change of the LED light string to be powered in real time, Set a threshold value for the voltage drop between the voltage acquisition output terminal ADC_12V and the reference signal input terminal PWM_REF, or set a constant value for the output voltage of the voltage acquisition output terminal ADC_12V (the voltage VREF of the reference signal input terminal PWM_REF is generally lower than small), when the voltage drop between the voltage acquisition output terminal ADC_12V and the reference signal input terminal PWM_REF is greater than the threshold, or the output voltage of the voltage acquisition output terminal ADC_12V is greater than the constant value, by adjusting the control in the front-end power supply circuit 101 The control signal PWM_12V of the signal input terminal Cont controls the optocoupler PCB101 to feed back the change of the working voltage of the LED light string (that is, the change of the voltage of the first power supply output terminal OUT1) to the PWM control chip UB101, and the PWM control chip UB101 controls the switching tube QB101 changes the duty ratio so that the voltage value of the voltage acquisition output terminal ADC_12V minus the voltage value of the reference signal input terminal PWM_REF is equal to or close to the preset threshold (or the voltage value of the voltage acquisition output terminal ADC_12V is equal to or close to the constant value). For example, set the constant value of the output voltage of the voltage acquisition output terminal ADC_12V to 2V, and when the ADC voltage starts to climb linearly from 0V to 2V when the circuit is started, the change of PWM_12V will stop; after the operation, due to the load change of the first power supply output terminal OUT1, The voltage coupled to the transformer will rise, and at this time the voltage will be greater than 2V, then after the ADC detects that it is greater than 2V, adjust the PWM_12V duty cycle again until the ADC voltage drops back to 2V, so that the voltage at both ends of the switch tube QB101 will stabilize at a Voltage around 2V. Therefore, this embodiment can limit the voltage drop between the voltage acquisition output terminal ADC_12V and the reference signal input terminal PWM_REF by controlling the control signal PWM_12V of the signal input terminal Cont, thereby reducing the drain-source voltage VDS of the switch tube QB1 from being affected by the LED lamp The influence of the voltage change of the string reduces the power consumption of the switching tube QB1 and ensures the power supply efficiency.
本发明提供的一种低功耗的恒流控制电路，设置有前端电源电路和后端线性恒流电路，利用前端电源电路调节两路输出的供电电压，并在前端电源电路中建立反馈调整电路，以及在反馈调整电路中设有控制信号输入端，以实现控制前端电源电路在第一供电输出端和第二供电输出端的电压；并通过设立后端线性恒流电路自动适应串联的LED背光灯数量的变化，可以根据LED背光灯串联后的电压值调整所述控制信号输入端的电压值，从而通过前端电源电路及其反馈调整电路控制所述第一供电输出端、第二供电输出端的输出电压，而第一供电输出端连接至LED背光灯进行供电，实现了与LED背光灯数量相适应的电压自动化调节，降低电路开关元件的功耗。A low-power constant current control circuit provided by the present invention is provided with a front-end power supply circuit and a rear-end linear constant-current circuit, the front-end power supply circuit is used to adjust the supply voltage of two outputs, and a feedback adjustment circuit is established in the front-end power supply circuit , and a control signal input terminal is provided in the feedback adjustment circuit to realize the control of the voltage of the front-end power supply circuit at the first power supply output terminal and the second power supply output terminal; and the back-end linear constant current circuit is set up to automatically adapt to the LED backlight in series The change of the quantity can adjust the voltage value of the control signal input terminal according to the voltage value of the LED backlight connected in series, so as to control the output voltage of the first power supply output terminal and the second power supply output terminal through the front-end power supply circuit and its feedback adjustment circuit , and the first power supply output end is connected to the LED backlight for power supply, which realizes the automatic adjustment of the voltage corresponding to the number of LED backlights and reduces the power consumption of the circuit switching elements.
参看图7，是本发明提供的低功耗的恒流控制电路的又一实施例的结构示意图。Referring to FIG. 7 , it is a schematic structural diagram of another embodiment of the low power consumption constant current control circuit provided by the present invention.
本实施例与前文所述的实施例的区别点在于，在前文所述的实施例的基础上，进一步地，本实施例提供的低功耗的恒流控制电路还包括一控制主芯片104。其中，前端电源电路101和后端线性恒流电路103的基本构造与工作原理与前文所述的实施例相同，在此不再赘述。The difference between this embodiment and the aforementioned embodiments is that, on the basis of the aforementioned embodiments, further, the low power consumption constant current control circuit provided by this embodiment further includes a control main chip 104 . Wherein, the basic structure and working principle of the front-end power supply circuit 101 and the back-end linear constant current circuit 103 are the same as those of the above-mentioned embodiments, and will not be repeated here.
所述控制主芯片104与所述控制信号输入端Cont、所述参考信号输入端PWM_REF以及所述电压采集输出端ADC_12V分别连接；The control main chip 104 is respectively connected to the control signal input terminal Cont, the reference signal input terminal PWM_REF and the voltage acquisition output terminal ADC_12V;
所述控制主芯片104根据所述电压采集输出端ADC_12V的电压变化，调节输出至所述控制信号输入端Cont的信号大小，以控制所述前端电源电路101的第一供电输出端OUT1、第二供电输出端OUT2的输出电压值；并通过所述参考信号输入端PWM_REF向所述后端线性恒流电路103输入所述恒流参考电压VREF。The control main chip 104 adjusts the magnitude of the signal output to the control signal input terminal Cont according to the voltage change of the voltage acquisition output terminal ADC_12V, so as to control the first power supply output terminal OUT1 and the second power supply output terminal OUT1 of the front-end power supply circuit 101. the output voltage value of the power supply output terminal OUT2; and input the constant current reference voltage VREF to the back-end linear constant current circuit 103 through the reference signal input terminal PWM_REF.
具体地，当所述控制主芯片104检测到所述电压采集输出端ADC_12V与所述参考信号输入端PWM_REF的电压差值大于预设的阈值时，所述控制主芯片104将输出至所述控制信号输入端Cont的电压信号占空比减小。具体实施时，所述控制主芯片104内置有模数转换器，用于将所述控制主芯片104接入的电压信号转换为数字信号。从电压采集输出端ADC_12V采集获得的电压信号首先经过模数转换器的转换后，获得相应的数字信号，再通过控制主芯片104中的其它处理单元的处理。另外，由于模数转换器的输入口最大工作电压为3.3V，过压容易损坏，而所述恒流控制电路1032与所述待供电LED灯串连接处P的电压往往会高于3.3V，因此，所述电压采集输出端ADC_12V还通过一降压电阻RB16连接到所述恒流控制电路1032与所述待供电LED灯串连接处P，以保证所述模数转换器的输入口最大电压不会高于3.3V。Specifically, when the control main chip 104 detects that the voltage difference between the voltage acquisition output terminal ADC_12V and the reference signal input terminal PWM_REF is greater than a preset threshold, the control main chip 104 will output to the control The duty cycle of the voltage signal at the signal input terminal Cont decreases. During specific implementation, the control main chip 104 has a built-in analog-to-digital converter for converting the voltage signal connected to the control main chip 104 into a digital signal. The voltage signal collected from the voltage collection output terminal ADC_12V is first converted by an analog-to-digital converter to obtain a corresponding digital signal, and then processed by controlling other processing units in the main chip 104 . In addition, since the maximum working voltage of the input port of the analog-to-digital converter is 3.3V, overvoltage is easy to damage, and the voltage at the connection point P between the constant current control circuit 1032 and the LED light string to be powered is often higher than 3.3V, Therefore, the voltage acquisition output terminal ADC_12V is also connected to the connection point P between the constant current control circuit 1032 and the LED light string to be powered through a voltage drop resistor RB16, so as to ensure the maximum voltage of the input port of the analog-to-digital converter It will not be higher than 3.3V.
本实施例由于采用了同一个控制主芯片对控制信号输入端Cont、所述参考信号输入端PWM_REF以及所述电压采集输出端ADC_12V三个端子的信号进行处理，因此在前文所述的有效效果的基础上，进一步地可以实时依据参考信号输入端PWM_REF以及电压采集输出端ADC_12V的信号变化而向控制信号输入端Cont发出相应的控制信号，因此可以迅速对LED灯串工作电压的变化进行响应。In this embodiment, the same control main chip is used to process the signals of the three terminals of the control signal input terminal Cont, the reference signal input terminal PWM_REF, and the voltage acquisition output terminal ADC_12V, so the effective effect described above On the basis, it can further send corresponding control signals to the control signal input terminal Cont according to the signal changes of the reference signal input terminal PWM_REF and the voltage acquisition output terminal ADC_12V in real time, so it can quickly respond to the change of the working voltage of the LED light string.
本发明还公开一种电视机，包括：电视机主板、背光LED灯串，以及如图2或图7所示的低功耗的恒流控制电路。所述低功耗的恒流控制电路与所述电视机主板和所述背光LED灯串分别连接，用于在打开所述电视机的电源时，根据所述背光LED灯串的工作电压，自适应调节供给所述电视机主板、所述背光LED灯串的电压信号。The present invention also discloses a television set, comprising: a mainboard of the television set, a backlight LED lamp string, and a low power consumption constant current control circuit as shown in FIG. 2 or FIG. 7 . The low power consumption constant current control circuit is respectively connected to the main board of the TV set and the backlight LED light string, and is used to automatically switch the power supply of the TV set according to the working voltage of the backlight LED light string when the power supply of the TV set is turned on. The voltage signal supplied to the TV main board and the backlight LED lamp string is adapted to be adjusted.
以上所述是本发明的优选实施方式，应当指出，对于本技术领域的普通技术人员来说，在不脱离本发明原理的前提下，还可以做出若干改进和润饰，这些改进和润饰也视为本发明的保护范围。The above description is a preferred embodiment of the present invention, and it should be pointed out that for those skilled in the art, without departing from the principle of the present invention, some improvements and modifications can also be made, and these improvements and modifications are also considered Be the protection scope of the present invention.
| Application Number | Priority Date | Filing Date | Title |
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| CN201410475845.6ACN104243876B (en) | 2014-09-17 | 2014-09-17 | Low-power-consumption constant current control circuit and television |
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| CN201410475845.6ACN104243876B (en) | 2014-09-17 | 2014-09-17 | Low-power-consumption constant current control circuit and television |
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| CN104243876B CN104243876B (en) | 2018-01-23 |
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| CN201410475845.6AActiveCN104243876B (en) | 2014-09-17 | 2014-09-17 | Low-power-consumption constant current control circuit and television |
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| PB01 | Publication | ||
| C10 | Entry into substantive examination | ||
| SE01 | Entry into force of request for substantive examination | ||
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