WO2011150772A1 - 一种多路led均流控制电路 - Google Patents

一种多路led均流控制电路 Download PDF

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Publication number
WO2011150772A1
WO2011150772A1 PCT/CN2011/074775 CN2011074775W WO2011150772A1 WO 2011150772 A1 WO2011150772 A1 WO 2011150772A1 CN 2011074775 W CN2011074775 W CN 2011074775W WO 2011150772 A1 WO2011150772 A1 WO 2011150772A1
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WIPO (PCT)
Prior art keywords
control circuit
led
tube
resistor
branch
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PCT/CN2011/074775
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English (en)
French (fr)
Inventor
韩雪强
刘永青
姜熠
Original Assignee
英飞特光电（杭州）有限公司
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Publication of WO2011150772A1 publication Critical patent/WO2011150772A1/zh

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Classifications

    • H—ELECTRICITY
    • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05B—ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL
    • H05B45/00—Circuit arrangements for operating light-emitting diodes [LED]
    • H05B45/40—Details of LED load circuits
    • H05B45/44—Details of LED load circuits with an active control inside an LED matrix
    • H05B45/46—Details of LED load circuits with an active control inside an LED matrix having LEDs disposed in parallel lines

Definitions

  • the invention relates to the technical field of LED illumination, in particular to a multi-channel LED current sharing control circuit. Background technique
  • LED lighting lamps include multiple parallel LED branches. If one of the LED branches has LED burned, the input current of the branch and other branches will become uneven, which will cause the entire LED lighting. Some of the internal LEDs become brighter and some of the LEDs become darker. Brightened LEDs can affect their life due to long-term operation at high currents, and too much current will cause LEDs to burn out. Darkened LEDs can affect lighting.
  • FIG. 1 the figure is a structural diagram of a multi-channel LED current control circuit in the prior art.
  • the technology uses a constant voltage module and a plurality of non-isolated DC/DC constant current circuits to form a current sharing control circuit, for example, including a non-isolated DC/DC constant current circuit 1, a non-isolated DC/DC constant current circuit 2, - until non-isolated DC/DC constant current circuit n.
  • the output of each non-isolated DC/DC constant current circuit is connected to the corresponding LED branch.
  • Each LED branch has a separate non-isolated DC/DC constant current circuit for constant current control, which makes it easier to implement multiple current sharing control.
  • this control circuit has a complicated structure, and each LED branch requires a separate control branch. Road, so the cost is higher.
  • FIG. 2 there is shown a block diagram of another multi-channel LED current control circuit in the prior art.
  • the technology adopts a voltage adjustable voltage regulator module and a plurality of linear adjustment constant current circuits to form a current sharing control circuit, for example, a linear adjustment constant current circuit 1, a linear adjustment constant current circuit 2, and a linear adjustment constant current circuit n.
  • the output of the voltage adjustable voltage regulator module is connected to the input end of each linear adjustment constant current circuit, and the output end of each linear adjustment constant current circuit is connected to the corresponding LED branch.
  • circuit structure shown in Figure 2 is also used for each LED with independent constant current control circuit.
  • the advantage is that it is easier to achieve current sharing control, but the disadvantage is control
  • the circuit structure is complicated, resulting in a high cost of the overall control circuit.
  • the technical problem to be solved by the present invention is to provide a multi-channel LED current sharing control circuit, which has a simple circuit structure and low cost.
  • the invention provides a multi-channel LED current sharing control circuit, comprising: a constant current source, a plurality of LED branches, and a control circuit corresponding to each LED branch;
  • Each of the control circuits includes: a drive resistor and an NPN tube;
  • One end of the driving resistor is connected to the positive end of the corresponding LED branch, and the other end is connected to the base of the NPN tube; the positive end of each LED branch is connected to the positive end of the constant current source;
  • the emitter of the NPN tube is connected to the negative end of the constant current source through a sampling resistor, and the collector is connected to the negative end of the LED branch;
  • a feedback resistor is connected between the base of the NPN tube in each control circuit and the emitter of the NPN tube in the next adjacent control circuit, and the base of the NPN tube in the last control circuit and the first control circuit
  • a feedback resistor is connected between the emitters of the NPN tubes.
  • each control circuit further includes a diode for correcting the feedback error
  • the positive terminal of the diode is coupled to the base of the NPN transistor in the control circuit, and the cathode is coupled through the feedback resistor to the emitter of the NPN transistor in the next adjacent control circuit.
  • each control circuit further includes a correction resistor and a modified PNP tube for correcting the feedback error
  • correction resistor is connected to the base of the NPN tube in the control circuit, and the other end is connected to the emitter of the modified PNP tube;
  • the collector of the PNP tube is connected to the negative terminal of the constant current source, and the base is connected to the emitter of the NPN tube in the next adjacent control circuit through a feedback resistor.
  • the invention also provides a multi-channel LED current sharing control circuit, comprising: a constant current source, a plurality of LED branches, and a control circuit corresponding to each LED branch;
  • Each of the control circuits includes: a driving resistor and a PNP tube;
  • One end of the driving resistor is connected to the negative end of the corresponding LED branch, and the other end is connected to the base of the PNP tube; the positive end of each LED branch is connected to the collector of the PNP tube; the negative of each LED branch Grounded at the end; The emitter of the PNP tube is connected to the positive end of the constant current source through a sampling resistor;
  • a feedback resistor is connected between the base of the PNP tube in each control circuit and the emitter of the PNP tube in the next adjacent control circuit, and the base of the PNP tube in the last control circuit and the first control circuit
  • a feedback resistor is connected between the emitters of the PNP tubes.
  • each control circuit further includes a diode for correcting the feedback error
  • the cathode of the diode is coupled to the base of the PNP tube, and the anode is coupled through the feedback resistor to the emitter of the PNP tube in the next adjacent control circuit.
  • each control circuit further includes a correction resistor and a modified NPN tube for correcting the feedback error
  • correction resistor is connected to the base of the PNP tube in the control circuit, and the other end is connected to the emitter of the modified NPN tube;
  • the collector of the NPN tube is connected to the positive terminal of the constant current source, and the base is connected to the emitter of the PNP tube in the next adjacent control circuit through a feedback resistor.
  • the invention also provides a multi-channel LED current sharing control circuit, comprising: a constant current source, a plurality of LED branches, and a control circuit corresponding to each LED branch;
  • Each of the control circuits includes: a driving resistor and an NMOS transistor;
  • One end of the driving resistor is connected to the positive end of the corresponding LED branch, and the other end is connected to the gate of the NMOS transistor; the positive end of each LED branch is connected to the positive end of the constant current source;
  • the source of the NMOS transistor is connected to the negative terminal of the constant current source through a sampling resistor, and the drain is connected to the negative terminal of the corresponding LED branch;
  • a feedback resistor is connected between the gate of the NMOS transistor in each control circuit and the source of the NMOS transistor in the next adjacent control circuit, and the gate of the NMOS transistor in the last control circuit and the first control circuit
  • a feedback resistor is connected between the sources of the NMOS transistors.
  • the invention also provides a multi-channel LED current sharing control circuit, comprising: a constant current source, a plurality of LED branches, and a control circuit corresponding to each LED branch;
  • Each of the control circuits includes: a driving resistor and a PMOS transistor;
  • One end of the driving resistor is connected to the negative end of the corresponding LED branch, and the other end is connected to the gate of the PMOS tube; the positive end of each LED branch is connected to the drain of the PMOS tube, and the negative of each LED branch Grounded at the end;
  • the source of the PMOS transistor is connected to the positive terminal of the constant current source through a sampling resistor;
  • a feedback resistor is connected between the gate of the PMOS transistor in each control circuit and the source of the PMOS transistor in the next adjacent control circuit, and the gate of the PMOS in the last control circuit is in the first control circuit
  • a feedback resistor is connected between the sources of the PMOS transistors.
  • the present invention has the following advantages:
  • the multi-channel LED current sharing control circuit controls the respective LED branches to achieve current sharing by setting a control circuit in each LED branch, and the closed loop cooperation between the respective control circuits.
  • the other LED branches prevent the current of the shorted LED branch from increasing, so that the current of each LED branch is the same as the current during normal operation. Since the current of each LED branch can be currentized, the current of each LED branch will always maintain one-N of the current of the constant current source (assuming there are N LED branches). Therefore, the control circuit does not need to separately detect which LED branch has a short circuit to separately adjust the current of the short-circuit LED branch.
  • the adjustment of the control circuit is an automatic adjustment of the closed loop, the cartridge is convenient, and only the switch tube and the resistor of the single tube are used. Basic components can be implemented at a lower cost.
  • FIG. 1 is a structural diagram of a multi-channel LED current control circuit in the prior art
  • FIG. 2 is another structural diagram of a multi-channel LED current control circuit in the prior art
  • FIG. 3 is a structural diagram of a multi-channel LED current sharing control circuit provided by the present invention.
  • FIG. 4 is a structural diagram of still another embodiment of a multi-channel LED current sharing control circuit provided by the present invention
  • FIG. 5 is a structural diagram of another embodiment of a multi-channel LED current sharing control circuit provided by the present invention
  • FIG. 7 is a structural diagram of still another embodiment of a control circuit composed of PNP provided by the present invention
  • FIG. 8 is a structural diagram of another embodiment of a control circuit composed of PNP provided by the present invention
  • a control circuit composed of NMOS tubes
  • Figure 10 is a control circuit composed of a PMOS transistor provided by the present invention.
  • the figure is a structural diagram of a multi-channel LED current sharing control circuit according to an embodiment of the present invention.
  • the multi-channel LED current sharing control circuit provided in this embodiment includes: a constant current source S1, a plurality of LED branches, and a control circuit corresponding to each LED branch;
  • the control circuit includes: a driving resistor and an NPN tube; the control circuit in the first LED branch in FIG. 3 includes a driving resistor Rd1 and an NPN tube Q11; and the control circuit in the second LED branch includes a driving resistor Rd2 and an NPN tube Q21;
  • the control circuit in the nLED branch includes a driving resistor Rdn and an NPN transistor Qnl.
  • Each LED branch includes n LED lights connected in series. As shown in FIG. 3, the first LED branch includes LEDs ... LEDln connected in series; the second LED branch includes LEDs 21...LED2n connected in series; the nth LED branch The road includes LEDnl ... LEDnn in series.
  • One end of the driving resistor is connected to the positive end of the corresponding LED branch, and the other end is connected to the base of the NPN tube; the positive end of each LED branch is connected to the positive end of the constant current source;
  • one end of the driving resistor Rd1 in the control circuit of the first LED branch is connected to the positive end of the first LED branch, and the other end of the Rd1 Connect the base of the NPN tube Q11.
  • the emitter of the NPN tube in each control circuit is connected to the negative terminal of the constant current source through a sampling resistor, and the collector is connected to the negative terminal of the corresponding LED branch; for example, the emitter of Q11 passes through the sampling resistor.
  • Rsl connects the negative terminal S - of S1.
  • a feedback resistor is connected between the base of the NPN tube in each control circuit and the emitter of the NPN tube in the next adjacent control circuit, and the base of the NPN tube in the last control circuit and the first control circuit
  • a feedback resistor is connected between the emitters of the NPN tubes.
  • the base of the NPN transistor Q11 in the control circuit corresponding to the first LED branch is connected to the emitter of the NPN transistor Q21 in the control circuit corresponding to the second LED branch through the feedback resistor Rfl.
  • the base of the NPN transistor Q21 in the control circuit corresponding to the second LED branch is connected to the emitter of the NPN transistor (not shown) in the control circuit corresponding to the third LED branch through the feedback resistor Rf2.
  • the base of the NPN tube Qnl in the control circuit corresponding to the last LED branch passes the feedback resistor
  • Rfn is connected to the emitter of the NPN transistor Q11 in the control circuit corresponding to the first LED branch.
  • the working principle of the control circuit is introduced by taking the first LED branch and the second LED branch as examples.
  • the first LED branch and the second LED branch can achieve good current sharing.
  • the NPN tubes Q11 and Q21 in the two control circuits operate in the critical saturation region.
  • the impedance of the first LED branch will decrease, causing the current Icl of the first LED branch to increase, so that the NPN tube Q11 enters the amplification region and As the current input to the collector of the NPN tube Q11 increases, the current at the emitter also increases. The voltage Vsl across the sampling resistor Rs1 of the NPN tube Q11 emitter is also increased.
  • Vbel Vbl-Vsl
  • Vbe2 Vb2-Vs2
  • Vs2 reduction will cause Vbe2 to increase, and the resistance of current Ic2 will decrease, which will eventually make the currents of the first LED branch and the second LED branch tend to be equal, thus realizing two LED branches.
  • the multi-channel LED current sharing control circuit controls the respective LED branches to achieve current sharing by setting control circuits in each LED branch, and each control circuit works cooperatively.
  • the other LED branches prevent the current of the shorted LED branch from increasing, so that the current of each LED branch is the same as the current during normal operation. Since the current of each LED branch can achieve current sharing, the current of each LED branch will always maintain one-N of the current of the constant current source (assuming there are N LED branches). Therefore, the control circuit does not have to separately detect which LED branch is short-circuited, thereby separately adjusting the current of the short-circuited LED branch.
  • the adjustment of the control circuit is an automatic adjustment of the closed loop, the cartridge is convenient, and only the switch tube of the single tube is used. Basic components such as resistors can be realized.
  • FIG. 4 the figure is a structural diagram of still another embodiment of a multi-channel LED current sharing control circuit provided by the present invention.
  • the multi-channel LED current sharing control circuit provided in this embodiment is different from that provided in FIG. 3 in that each control circuit adds a diode for correcting feedback error;
  • a diode for correcting an error is connected in series with the feedback resistor, and a positive terminal of the series branch formed by the diode and the feedback resistor is connected to a base of the NPN tube in the control circuit, and a negative terminal of the series branch is connected The emitter of the NPN tube in the next adjacent control circuit.
  • the positive end of the series branch is the other end of the feedback resistor, and the negative end is the cathode of the diode; when one end of the feedback resistor is connected to the diode cathode, The positive terminal of the series branch is the anode of the diode, and the negative terminal is the other end of the feedback resistor.
  • the control circuit of the first LED branch adds a diode Dl1
  • the control circuit of the second LED branch adds a diode D21
  • the control circuit of the n-th LED branch adds a diode Dnl.
  • the role of the diode is to reduce the feedback error, provide the accuracy of the current adjustment, and compensate for the temperature drift.
  • this embodiment further provides a circuit for correcting feedback error.
  • FIG. 5 the figure is a structural diagram of another embodiment of a multi-channel LED current sharing control circuit provided by the present invention.
  • the correction circuit provided in the embodiment shown in Fig. 5 includes a correction resistor and a modified PNP tube.
  • correction resistor is connected to the base of the NPN tube in the control circuit, and the other end is connected to the emitter of the modified PNP tube;
  • the collector of the PNP tube is connected to the negative terminal S- of the constant current source, and the base is connected to the emitter of the NPN tube in the next adjacent control circuit through a feedback resistor.
  • the correction circuit in the control circuit of the first LED branch includes a correction resistor R11 and a modified PNP tube Q12; the correction circuit in the control circuit of the second LED branch includes a correction resistor R21 and a modified PNP tube Q22;
  • the correction circuit in the control circuit of the nLED branch includes a correction resistor Rn1 and a modified PNP tube Qn2.
  • the control circuit provided in the above embodiment is an NPN tube. It can be understood that the operation principle of the NPN tube is similar to that of the PNP tube. Therefore, the PNP tube can also be used.
  • the control circuit in FIG. 6-8 is composed of a PNP tube and a driving resistor. .
  • FIG. 6 is a structural diagram of still another control circuit according to an embodiment of the present invention. Due to the dual principle of the NPN tube and the PNP tube, the multi-channel LED current sharing control circuit provided by the embodiment includes: a constant current source S1, a plurality of LED branches, and a control circuit corresponding to each LED branch; The control circuit includes: a driving resistor and a PNP tube;
  • One end of the driving resistor is connected to the negative end of the corresponding LED branch, and the other end is connected to the base of the PNP tube; the positive end of each LED branch is connected to the collector of the PNP tube; the negative of each LED branch Terminating the negative terminal of the constant current source S1;
  • the emitter of the PNP tube is connected to the positive end of the constant current source through a sampling resistor;
  • a feedback resistor is connected between the base of the PNP tube in each control circuit and the emitter of the PNP tube in the next adjacent control circuit, and the base of the PNP tube in the last control circuit and the first control circuit
  • a feedback resistor is connected between the emitters of the PNP tubes.
  • the control circuit of the first LED branch includes a driving resistor Rd1 and a PNP tube Q11; the control circuit of the second LED branch includes a driving resistor Rd2 and a PNP tube Q21; the control circuit of the nLED branch includes a driving Resistor Rdn and PNP tube Qnl.
  • sampling resistors Rsl, Rs2, and Rsn in Fig. 6 have the same functions as the sampling resistors in Fig. 3, and the connection relationships are similar, and will not be described again.
  • the feedback resistors Rfl, Rf2, and Rfn in FIG. 6 have the same functions as the feedback resistors in FIG. 3, and the connection relationships are similar, and will not be described herein.
  • the control circuit composed of PNP has the same working principle as the control circuit composed of NPN tubes, and will not be described here.
  • the control circuit consisting of PNP tubes can also include a correction circuit that corrects the feedback error, see figure
  • the correction circuit is implemented by a correction diode.
  • the diodes in the correction circuit corresponding to each LED branch are D11 and D21, respectively.
  • a diode for correcting an error is connected in series with the feedback resistor, and a negative end of the series branch formed by the diode and the feedback resistor is connected to a base of the PNP tube, and a positive end of the series branch is connected to a next adjacent The emitter of the PNP tube in the control circuit.
  • the series branches corresponding to the first LED branch are D11 and Rfl; the series branches corresponding to the second LED branch are D21 and Rf2; and the series branches corresponding to the third LED branch are Dnl and Rfn.
  • the positive end of the series branch is the other end of the feedback resistor, and the negative end is the cathode of the diode; when one end of the feedback resistor is connected to the diode cathode, The positive terminal of the series branch is the anode of the diode, and the negative terminal is the other end of the feedback resistor.
  • the correction circuit in Fig. 7 is only described by taking the first LED branch and the second LED branch as an example.
  • the series branch corresponding to the first LED branch includes D11 and Rfl; wherein, the cathode of D11 is connected to the base of PNP tube Q11; the end of Rfl not connected to D11 is connected to the emitter of PNP tube Q21;
  • the correction circuit corresponding to the branch is the same as this, and is not repeated here.
  • the correction circuit can also be a correction resistor and a modified NPN tube.
  • the circuit shown in Fig. 8 differs from that of Fig. 7 in that a correction circuit is added.
  • correction resistor is connected to the base of the PNP tube in the control circuit, and the other end is connected to the emitter of the modified NPN tube;
  • the collector of the NPN tube is connected to the positive terminal of the constant current source, and the base is connected to the emitter of the PNP tube in the next adjacent control circuit through a feedback resistor.
  • the correction circuit in the control circuit of the first LED branch includes a correction resistor R12 and a modified NPN tube Q13;
  • the correction circuit in the control circuit of the second LED branch includes a correction resistor R22 and a modified NPN tube Q23;
  • the correction circuit in the control circuit of the nLED branch includes a correction resistor Rn2 and a modified NPN transistor Qn3.
  • control circuit can also be implemented by an NMOS transistor and a PMOS transistor. This will be described in detail below in conjunction with Figures 9 and 10.
  • the figure is a schematic diagram of a control circuit composed of an NMOS transistor provided by the present invention.
  • the multi-channel LED current sharing control circuit provided in this embodiment includes: a constant current source, a plurality of LED branches, and a control circuit corresponding to each LED branch;
  • Each of the control circuits includes: a driving resistor and an NMOS transistor;
  • One end of the driving resistor is connected to the positive end of the corresponding LED branch, and the other end is connected to the gate of the NMOS transistor; the positive end of each LED branch is connected to the positive end of the constant current source;
  • the source of the NMOS transistor is connected to the negative terminal of the constant current source through a sampling resistor, and the drain is connected to the negative terminal of the corresponding LED branch;
  • a feedback resistor is connected between the source of the tube, and a feedback resistor is connected between the gate of the NMOS transistor in the last control circuit and the source of the NMOS transistor in the first control circuit.
  • the control circuit corresponding to the first LED branch includes a driving resistor Rd1 and an NMOS transistor Q11; the control circuit corresponding to the second LED branch includes a driving resistor Rd2 and an NMOS transistor Q21; and a control corresponding to the third LED branch
  • the circuit includes a driving resistor Rdn and an NMOS transistor Qnl.
  • the feedback resistance corresponding to each LED branch is Rf 1, Rf2, Rfn;
  • the corresponding resistors for each LED branch are Rsl, Rs2, and Rsn.
  • the figure is a schematic diagram of a control circuit composed of a PMOS tube provided by the present invention.
  • the multi-channel LED current sharing control circuit provided in this embodiment includes: a constant current source, a plurality of LED branches, and a control circuit corresponding to each LED branch;
  • Each of the control circuits includes: a driving resistor and a PMOS transistor;
  • One end of the driving resistor is connected to the negative end of the corresponding LED branch, and the other end is connected to the gate of the PMOS tube; the positive end of each LED branch is connected to the drain of the PMOS tube, and the negative of each LED branch Grounded at the end;
  • the source of the PMOS transistor is connected to the positive terminal of the constant current source through a sampling resistor;
  • a feedback resistor is connected between the gate of the PMOS transistor in each control circuit and the source of the PMOS transistor in the next adjacent control circuit, and the gate of the PMOS in the last control circuit is in the first control circuit
  • a feedback resistor is connected between the sources of the PMOS transistors.
  • the control circuit corresponding to the first LED branch includes a driving resistor Rd1 and a PMOS transistor Q11; the control circuit corresponding to the second LED branch includes a driving resistor Rd2 and a PMOS transistor Q21; and a control corresponding to the third LED branch
  • the circuit includes a driving resistor Rdn and a PMOS transistor Qnl.
  • the feedback resistance corresponding to each LED branch is Rf 1, Rf2, Rfn;
  • the corresponding resistors for each LED branch are Rsl, Rs2, and Rsn.
  • control circuit composed of the NMOS transistor or the PMOS transistor is the same as that of the control circuit composed of the NPN transistor, and will not be described herein.
  • the above embodiment respectively introduces a method for multi-channel LED current sharing realized by a control circuit composed of an NPN tube, a PNP tube, an NMOS tube and a PMOS tube. No matter which switch tube is used, a closed loop automatic connection between each LED branch can be realized. For the purpose of adjustment, the control circuit has a simple structure and low cost.

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Description

一种多路 LED均流控制电路
本申请要求于 2010 年 6 月 1 日提交中国专利局、 申请号为 201010192631.X, 发明名称为"一种多路 LED均流控制电路 "的中国专利申请 的优先权， 其全部内容通过引用结合在本申请中。
技术领域
本发明涉及 LED照明技术领域， 特别涉及一种多路 LED均流控制电路。 背景技术
目前很多 LED照明灯内部包括多路并联的 LED支路，如果其中一路 LED 支路上有 LED烧毁， 则该支路和其他支路的输入电流会变得大小不均等， 这 样会造成整个 LED照明灯内部有的 LED变亮、 有的 LED变暗。 变亮的 LED 由于长期工作于大电流状态下， 会影响其寿命， 并且， 电流太大将造成 LED 烧毁。 变暗的 LED会影响照明效果。
现有技术中解决以上出现的问题大部分采用的是对各个 LED支路的电流 进行独立控制。
参见图 1 , 该图为现有技术中多路 LED电流控制电路的结构图。
该技术是采用恒压模块和多个非隔离 DC/DC 恒流电路组成均流控制电 路， 例如包括非隔离 DC/DC恒流电路 1、 非隔离 DC/DC恒流电路 2, —直到 非隔离 DC/DC恒流电路 n。每个非隔离 DC/DC恒流电路的输出端连接对应的 LED支路。 每路 LED支路有单独的非隔离 DC/DC恒流电路来做恒流控制， 这样比较容易实现多路均流控制， 但是这种控制电路结构复杂， 每路 LED支 路需要单独的控制支路， 因此成本较高。
参见图 2, 该图为现有技术中另一种多路 LED电流控制电路的结构图。 该技术是采用电压可调稳压模块和多个线性调整恒流电路组成均流控制 电路， 例如包括线性调整恒流电路 1、 线性调整恒流电路 2, —直到线性调整 恒流电路 n。 电压可调稳压模块的输出端连接每个线性调整恒流电路的输入 端， 每个线性调整恒流电路的输出端连接对应的 LED支路。 线性调整恒流电 路由 MOS管或三极管来实现线性调整。
与图 1所示的电路结构相似， 图 2所示的电路结构也是针对每路 LED采 用独立的恒流控制电路，优点是比较容易实现均流控制，但是这样的缺点是控 制电路结构复杂， 造成整体的控制电路成本较高。
发明内容
本发明要解决的技术问题是提供一种多路 LED均流控制电路， 电路结构 筒单， 成本低。
本发明提供一种多路 LED均流控制电路， 包括： 恒流源、多个 LED支路、 每个 LED支路对应一个控制电路；
每个所述控制电路包括： 驱动电阻和 NPN管；
所述驱动电阻的一端连接对应 LED支路的正端 ,另一端连接所述 NPN管 的基极； 每个 LED支路的正端连接所述恒流源的正端；
所述 NPN管的发射极通过采样电阻连接所述恒流源的负端， 集电极连接 对应 LED支路的负端；
每个控制电路中的 NPN管的基极与下一个相邻的控制电路中的 NPN管的 发射极之间连接有反馈电阻， 最后一个控制电路中的 NPN管的基极与第一个 控制电路中的 NPN管的发射极之间连接有反馈电阻。
优选地， 每个控制电路还包括用于修正反馈误差的二极管；
所述二极管的正端连接所述控制电路中的 NPN管的基极， 阴极通过所述 反馈电阻连接下一个相邻的控制电路中的 NPN管的发射极。
优选地， 每个控制电路还包括用于修正反馈误差的修正电阻和修正 PNP 管，
所述修正电阻的一端连接所述控制电路中的 NPN管的基极， 另一端连接 修正 PNP管的发射极；
修正 PNP管的集电极连接所述恒流源的负端， 基极通过反馈电阻连接下 一个相邻的控制电路中的 NPN管的发射极。
本发明还提供一种多路 LED均流控制电路， 包括： 恒流源、 多个 LED支 路、 每个 LED支路对应一个控制电路；
每个所述控制电路包括： 驱动电阻和 PNP管；
所述驱动电阻的一端连接对应 LED支路的负端， 另一端连接所述 PNP管 的基极； 每个 LED支路的正端连接所述 PNP管的集电极； 每个 LED支路的 负端接地； 所述 PNP管的发射极通过采样电阻连接恒流源的正端；
每个控制电路中的 PNP管的基极与下一个相邻的控制电路中的 PNP管的 发射极之间连接有反馈电阻， 最后一个控制电路中的 PNP管的基极与第一个 控制电路中的 PNP管的发射极之间连接有反馈电阻。
优选地， 每个控制电路还包括用于修正反馈误差的二极管；
所述二极管的阴极连接所述 PNP管的基极， 阳极通过所述反馈电阻连接 下一个相邻的控制电路中的 PNP管的发射极。
优选地， 每个控制电路还包括用于修正反馈误差的修正电阻和修正 NPN 管；
所述修正电阻的一端连接所述控制电路中的 PNP管的基极， 另一端连接 修正 NPN管的发射极；
修正 NPN管的集电极连接所述恒流源的正端， 基极通过反馈电阻连接下 一个相邻的控制电路中的 PNP管的发射极。
本发明还提供一种多路 LED均流控制电路， 包括： 恒流源、 多个 LED支 路、 每个 LED支路对应一个控制电路；
每个所述控制电路包括： 驱动电阻和 NMOS管；
所述驱动电阻的一端连接对应 LED支路的正端， 另一端连接所述 NMOS 管的栅极； 每个 LED支路的正端连接所述恒流源的正端；
所述 NMOS管的源极通过采样电阻连接所述恒流源的负端， 漏极连接对 应 LED支路的负端；
每个控制电路中的 NMOS管的栅极与下一个相邻的控制电路中的 NMOS 管的源极之间连接有反馈电阻， 最后一个控制电路中的 NMOS管的栅极与第 一个控制电路中的 NMOS管的源极之间连接有反馈电阻。
本发明还提供一种多路 LED均流控制电路， 包括： 恒流源、 多个 LED支 路、 每个 LED支路对应一个控制电路；
每个所述控制电路包括： 驱动电阻和 PMOS管；
所述驱动电阻的一端连接对应 LED支路的负端， 另一端连接所述 PMOS 管的栅极；每个 LED支路的正端连接所述 PMOS管的漏极，每个 LED支路的 负端接地； 所述 PMOS管的源极通过采样电阻连接恒流源的正端；
每个控制电路中的 PMOS管的栅极与下一个相邻的控制电路中的 PMOS 管的源极之间连接有反馈电阻， 最后一个控制电路中的 PMOS 的栅极与第一 个控制电路中的 PMOS管的源极之间连接有反馈电阻。
与现有技术相比， 本发明具有以下优点：
本实施例提供的多路 LED均流控制电路通过在每个 LED支路设置控制电 路， 并且各个控制电路之间闭环协同工作来控制各个 LED支路实现均流。 当 有一个或多个 LED支路中出现 LED灯短路时， 其他 LED支路阻止短路 LED 支路的电流增大， 从而实现各个 LED支路的电流与正常工作时的电流相同。 由于各个 LED支路的电流可以实现均流， 因此， 每个 LED支路的电流将永远 保持恒流源的电流的 N分之一 (假设有 N个 LED支路）。 因此， 该控制电路 不必单独检测哪个 LED支路出现短路来单独调节该短路 LED支路的电流，该 控制电路的调节是闭环的自动调节， 筒单方便， 并且仅用筒单的开关管和电阻 等基本器件即可实现， 成本较低。
附图说明
图 1是现有技术中多路 LED电流控制电路的结构图；
图 2是现有技术中多路 LED电流控制电路的又一种结构图；
图 3是本发明提供的多路 LED均流控制电路结构图；
图 4是本发明提供的多路 LED均流控制电路又一实施例结构图； 图 5是本发明提供的多路 LED均流控制电路另一实施例结构图； 图 6是本发明提供的由 PNP组成的控制电路的结构图；
图 7是本发明提供的由 PNP组成的控制电路的又一实施例结构图； 图 8是本发明提供的由 PNP组成的控制电路的另一实施例结构图； 图 9是本发明提供的由 NMOS管组成的控制电路；
图 10是本发明提供的由 PMOS管组成的控制电路。
具体实施方式
为使本发明的上述目的、 特征和优点能够更加明显易懂， 下面结合附图对 本发明的具体实施方式做详细的说明。
参见图 3 , 该图为本发明实施例提供的多路 LED均流控制电路结构图。 本实施例提供的多路 LED均流控制电路包括： 恒流源 Sl、 多个 LED支 路、 每个 LED支路对应一个控制电路；
所述控制电路包括： 驱动电阻和 NPN管； 如图 3中第一 LED支路中的控 制电路包括驱动电阻 Rdl和 NPN管 Q11 ;第二 LED支路中的控制电路包括驱 动电阻 Rd2和 NPN管 Q21； 第 nLED支路中的控制电路包括驱动电阻 Rdn和 NPN管 Qnl。
每个 LED支路包括 n个串联的 LED灯， 如图 3所示， 第一 LED支路包 括串联的 LEDll ...LEDln; 第二 LED 支路包括串联的 LED21...LED2n; 第 nLED支路包括串联的 LEDnl ... LEDnn。
所述驱动电阻的一端连接对应 LED支路的正端 ,另一端连接所述 NPN管 的基极； 每个 LED支路的正端连接所述恒流源的正端；
以第一 LED支路和第二 LED支路为例， 如图 3所示， 第一 LED支路的 控制电路中的驱动电阻 Rdl的一端连接第一 LED支路的正端， Rdl的另一端 连接 NPN管 Q11的基极。
如图 3所示， 每个控制电路中的 NPN管的发射极通过采样电阻连接所述 恒流源的负端， 集电极连接对应 LED支路的负端； 例如， Q11的发射极通过 采样电阻 Rsl连接 S1的负端 S -。
每个控制电路中的 NPN管的基极与下一个相邻的控制电路中的 NPN管的 发射极之间连接有反馈电阻， 最后一个控制电路中的 NPN管的基极与第一个 控制电路中的 NPN管的发射极之间连接有反馈电阻。
如图 3所示，第一 LED支路对应的控制电路中的 NPN管 Q11的基极通过 反馈电阻 Rfl连接第二 LED支路对应的控制电路中的 NPN管 Q21的发射极。
第二 LED支路对应的控制电路中的 NPN管 Q21的基极通过反馈电阻 Rf2 连接第三 LED支路对应的控制电路中的 NPN管 （图中未示出） 的发射极。
最后一个 LED支路对应的控制电路中的 NPN管 Qnl的基极通过反馈电阻
Rfn连接第一 LED支路对应的控制电路中的 NPN管 Q11的发射极。
以上是本发明实施例提供的多路 LED均流控制电路的连接关系， 下面结 合附图 3以两个 LED支路为例详细介绍本发明实施例的工作原理。
以第一 LED支路和第二 LED支路为例介绍控制电路的工作原理： 当电路正常工作时，第一 LED支路和第二 LED支路能够实现良好的均流， 此时， 两个控制电路中的 NPN管 Q11和 Q21工作于临界饱和区。
假设第一 LED支路中有一个或多个 LED短路， 则第一 LED支路的阻抗 将减小，导致第一 LED支路的电流 Icl将增大，从而 NPN管 Q11进入放大区， 并且随着输入 NPN管 Q11集电极的电流增大， 其发射极的电流也随之增大。 NPN管 Q11发射极连接的采样电阻 Rsl上的电压 Vsl也增大。由于恒流源 S1 输出的总电流 Io恒定，因此， Icl增大将导致第二 LED支路上的电流 Ic2减小， 第二控制电路中的 NPN管 Q21进入饱和区， 并且随着输入 NPN管 Q21集电 极的电流减小， NPN管 Q21发射极的电流也随之减小。 这样， NPN管 Q21发 射极上连接的采样电阻 Rs2上的电压 Vs2也减小。 Vs2减小将使 NPN管 Q11 的基极电压 Vbl减小， 根据 NPN管的工作原理 Vbel=Vbl-Vsl , 因此， NPN 管 Q11的 Vbel将减小， 这样将阻止电流 Icl增大， 同时根据 Vbe2=Vb2-Vs2, Vs2减小将导致 Vbe2增大， 阻值了电流 Ic2的减小， 这样最终使第一 LED支 路和第二 LED支路的电流趋向于相等，从而实现两路 LED支路的自动均流调 节。
需要说明的是， 以上仅是以两路 LED支路为例来介绍本实施例提供的均 流控制电路的工作原理， 可以理解的是， 多路 LED支路时其工作原理相同， 在此不再赘述。
本实施例提供的多路 LED均流控制电路通过在每个 LED支路设置控制电 路， 并且每个控制电路之间协同工作来控制各个 LED支路实现均流。 当有一 个或多个 LED支路中出现 LED灯短路时， 其他 LED支路阻止该短路 LED支 路的电流增大， 从而实现各个 LED支路的电流与正常工作时的电流相同。 由 于各个 LED支路的电流可以实现均流， 因此， 每个 LED支路的电流将永远保 持恒流源的电流的 N分之一（假设有 N个 LED支路）。 因此， 该控制电路不 必单独检测哪个 LED支路出现短路， 从而单独调节该短路 LED支路的电流， 该控制电路的调节是闭环的自动调节， 筒单方便， 并且仅用筒单的开关管和电 阻等基本器件即可实现。
参见图 4, 该图为本发明提供的多路 LED均流控制电路又一实施例结构 图。 本实施例提供的多路 LED均流控制电路与图 3提供的区别是每个控制电 路增加了用于修正反馈误差的二极管；
用于修正误差的二极管与所述反馈电阻串联，由所述二极管和反馈电阻构 成的串联支路的正端连接所述控制电路中的 NPN管的基极， 所述串联支路的 负端连接下一个相邻的控制电路中的 NPN管的发射极。
其中， 当所述反馈电阻的一端连接二极管阳极时， 所述串联支路的正端为 所述反馈电阻的另一端， 负端为二极管的阴极； 当所述反馈电阻的一端连接二 极管阴极时， 所述串联支路的正端为所述二极管的阳极， 负端为反馈电阻的另 一端。
如图 4所示， 第一 LED支路的控制电路增加了二极管 Dl 1 , 第二 LED支 路的控制电路增加了二极管 D21 ,第 nLED支路的控制电路增加了二极管 Dnl。
增加二极管的作用是可以减小反馈误差， 提供电流调整的精度， 补偿温度 漂移。
需要说明的是， 本实施例还提供了一种修正反馈误差的电路， 参见图 5 , 该图为本发明提供的多路 LED均流控制电路另一实施例结构图。
该实施例与图 4所示的实施例不同的是提供的修正电路不同，图 5所示的 实施例提供的修正电路包括修正电阻和修正 PNP管。
所述修正电阻的一端连接所述控制电路中的 NPN管的基极， 另一端连接 修正 PNP管的发射极；
修正 PNP管的集电极连接所述恒流源的负端 S- , 基极通过反馈电阻连接 下一个相邻的控制电路中的 NPN管的发射极。
如图 5所示， 第一 LED支路的控制电路中的修正电路包括修正电阻 R11 和修正 PNP管 Q12; 第二 LED支路的控制电路中的修正电路包括修正电阻 R21和修正 PNP管 Q22; 第 nLED支路的控制电路中的修正电路包括修正电 阻 Rnl和修正 PNP管 Qn2。
以上实施例提供的控制电路中是 NPN管，可以理解的根据 NPN管与 PNP 管的工作原理相似， 因此也可以用 PNP管， 图 6-8中的控制电路是由 PNP管 和驱动电阻组成的。
参见图 6, 该图为本发明实施例提供的又一控制电路结构图。 由于 NPN管与 PNP管的对偶原理， 本实施例提供的多路 LED均流控制 电路， 包括： 恒流源 Sl、 多个 LED支路、 每个 LED支路对应一个控制电路； 每个所述控制电路包括： 驱动电阻和 PNP管；
所述驱动电阻的一端连接对应 LED支路的负端， 另一端连接所述 PNP管 的基极； 每个 LED支路的正端连接所述 PNP管的集电极； 每个 LED支路的 负端接恒流源 S1的负端；
所述 PNP管的发射极通过采样电阻连接恒流源的正端；
每个控制电路中的 PNP管的基极与下一个相邻的控制电路中的 PNP管的 发射极之间连接有反馈电阻， 最后一个控制电路中的 PNP管的基极与第一个 控制电路中的 PNP管的发射极之间连接有反馈电阻。
如图 6所示，第一 LED支路的控制电路包括驱动电阻 Rdl和 PNP管 Ql 1； 第二 LED支路的控制电路包括驱动电阻 Rd2和 PNP管 Q21 ; 第 nLED支路的 控制电路包括驱动电阻 Rdn和 PNP管 Qnl。
图 6中的采样电阻 Rsl、 Rs2、 Rsn与图 3中的采样电阻的作用相同， 连 接关系相似， 在此不再赘述。
图 6中的反馈电阻 Rfl、 Rf2、 Rfn与图 3中的反馈电阻的作用相同， 连接 关系相似， 在此不再赘述。
由 PNP组成的控制电路与由 NPN管组成的控制电路的工作原理相同， 在 此不再赘述。
由 PNP管组成的控制电路也可以包括修正反馈误差的修正电路， 参见图
7, 该修正电路是由修正二极管实现的。
图 7与图 6的区别是增加了由二极管组成的修正电路。
如图 7所示，每个 LED支路对应的修正电路中的二极管分别为 D11、D21、
Dnl。
用于修正误差的二极管与所述反馈电阻串联，由所述二极管和反馈电阻构 成的串联支路的负端连接所述 PNP管的基极， 所述串联支路的正端连接下一 个相邻的控制电路中的 PNP管的发射极。
第一 LED支路对应的串联支路为 D11和 Rfl ; 第二 LED支路对应的串联 支路为 D21和 Rf2; 第三 LED支路对应的串联支路为 Dnl和 Rfn。 其中， 当所述反馈电阻的一端连接二极管阳极时， 所述串联支路的正端为 所述反馈电阻的另一端， 负端为二极管的阴极； 当所述反馈电阻的一端连接二 极管阴极时， 所述串联支路的正端为所述二极管的阳极， 负端为反馈电阻的另 一端。
图 7中的修正电路仅以第一 LED支路和第二 LED支路为例进行介绍。 如图 7所示， 第一 LED支路对应的串联支路包括 D11和 Rfl ; 其中， D11 的阴极连接 PNP管 Q11的基极； Rfl未连接 D11的一端连接 PNP管 Q21的发 射极； 其他 LED支路对应的修正电路与此相同， 在此不再——赘述。
需要说明的是， 参见图 8, 该修正电路也可以为修正电阻和修正 NPN管。 图 8所示的电路与图 7的区别是增加了修正电路。
所述修正电阻的一端连接所述控制电路中的 PNP管的基极， 另一端连接 修正 NPN管的发射极；
修正 NPN管的集电极连接所述恒流源的正端， 基极通过反馈电阻连接下 一个相邻的控制电路中的 PNP管的发射极。
如图 8所示， 第一 LED支路的控制电路中的修正电路包括修正电阻 R12 和修正 NPN管 Q13; 第二 LED支路的控制电路中的修正电路包括修正电阻 R22和修正 NPN管 Q23; 第 nLED支路的控制电路中的修正电路包括修正电 阻 Rn2和修正 NPN管 Qn3。
可以理解的是， 控制电路也可以由 NMOS管和 PMOS管来实现。 下面结 合图 9和图 10来详细说明。
参见图 9, 该图为本发明提供的由 NMOS管组成的控制电路示意图。 本实施例提供的多路 LED均流控制电路， 包括： 恒流源、多个 LED支路、 每个 LED支路对应一个控制电路；
每个所述控制电路包括： 驱动电阻和 NMOS管；
所述驱动电阻的一端连接对应 LED支路的正端， 另一端连接所述 NMOS 管的栅极； 每个 LED支路的正端连接所述恒流源的正端；
所述 NMOS管的源极通过采样电阻连接所述恒流源的负端， 漏极连接对 应 LED支路的负端；
每个控制电路中的 NMOS管的栅极与下一个相邻的控制电路中的 NMOS 管的源极之间连接有反馈电阻， 最后一个控制电路中的 NMOS管的栅极与第 一个控制电路中的 NMOS管的源极之间连接有反馈电阻。
如图 9所示， 第一 LED支路对应的控制电路包括驱动电阻 Rdl和 NMOS 管 Q11 ; 第二 LED支路对应的控制电路包括驱动电阻 Rd2和 NMOS管 Q21 ; 第三 LED支路对应的控制电路包括驱动电阻 Rdn和 NMOS管 Qnl。
每个 LED支路对应的反馈电阻分别是 Rf 1、 Rf2、 Rfn;
每个 LED支路对应的采用电阻分别是 Rsl、 Rs2、 Rsn。
参见图 10, 该图为本发明提供的由 PMOS管组成的控制电路示意图。 本实施例提供的多路 LED均流控制电路， 包括： 恒流源、多个 LED支路、 每个 LED支路对应一个控制电路；
每个所述控制电路包括： 驱动电阻和 PMOS管；
所述驱动电阻的一端连接对应 LED支路的负端， 另一端连接所述 PMOS 管的栅极；每个 LED支路的正端连接所述 PMOS管的漏极，每个 LED支路的 负端接地；
所述 PMOS管的源极通过采样电阻连接恒流源的正端；
每个控制电路中的 PMOS管的栅极与下一个相邻的控制电路中的 PMOS 管的源极之间连接有反馈电阻， 最后一个控制电路中的 PMOS 的栅极与第一 个控制电路中的 PMOS管的源极之间连接有反馈电阻。
如图 10所示，第一 LED支路对应的控制电路包括驱动电阻 Rdl和 PMOS 管 Q11 ; 第二 LED支路对应的控制电路包括驱动电阻 Rd2和 PMOS管 Q21 ; 第三 LED支路对应的控制电路包括驱动电阻 Rdn和 PMOS管 Qnl。
每个 LED支路对应的反馈电阻分别是 Rf 1、 Rf2、 Rfn;
每个 LED支路对应的采用电阻分别是 Rsl、 Rs2、 Rsn。
需要说明的是， 由 NMOS管或 PMOS管组成的控制电路的工作原理与由 NPN管组成的控制电路的工作原理相同， 在此不再赘述。
以上实施例分别介绍了由 NPN管、 PNP管、 NMOS管和 PMOS管组成的 控制电路实现的多路 LED均流的方法， 无论使用那种开关管， 均可以实现各 个 LED支路之间闭环自动调节的目的， 该控制电路结构筒单， 成本低。
以上所述，仅是本发明的较佳实施例而已，并非对本发明作任何形式上的限制。 虽然本发明已以较佳实施例揭露如上， 然而并非用以限定本发明。任何熟悉本 领域的技术人员， 在不脱离本发明技术方案范围情况下， 都可利用上述揭示的 方法和技术内容对本发明技术方案做出许多可能的变动和修饰，或修改为等同 变化的等效实施例。 因此， 凡是未脱离本发明技术方案的内容， 依据本发明的 技术实质对以上实施例所做的任何筒单修改、等同变化及修饰， 均仍属于本发 明技术方案保护的范围内。

Claims

权 利 要 求
1、 一种多路 LED均流控制电路， 其特征在于， 包括： 恒流源、 多个 LED 支路、 每个 LED支路对应一个控制电路；
每个所述控制电路包括： 驱动电阻和 NPN管；
所述驱动电阻的一端连接对应 LED支路的正端 ,另一端连接所述 NPN管 的基极； 每个 LED支路的正端连接所述恒流源的正端；
所述 NPN管的发射极通过采样电阻连接所述恒流源的负端， 集电极连接 对应 LED支路的负端；
每个控制电路中的 NPN管的基极与下一个相邻的控制电路中的 NPN管的 发射极之间连接有反馈电阻， 最后一个控制电路中的 NPN管的基极与第一个 控制电路中的 NPN管的发射极之间连接有反馈电阻。
2、 根据权利要求 1所述的多路 LED均流控制电路， 其特征在于， 每个控 制电路还包括用于修正反馈误差的二极管；
所述二极管与所述的反馈电阻串联，所述的串联支路的正端连接所述控制 电路中的 NPN管的基极， 所述的串联支路的负端连接下一个相邻的控制电路 中的 NPN管的发射极。
3、 根据权利要求 1所述的多路 LED均流控制电路， 其特征在于， 每个控 制电路还包括用于修正反馈误差的修正电阻和修正 PNP管，
所述修正电阻的一端连接所述控制电路中的 NPN管的基极， 另一端连接 修正 PNP管的发射极；
修正 PNP管的集电极连接所述恒流源的负端， 基极通过反馈电阻连接下 一个相邻的控制电路中的 NPN管的发射极。
4、 一种多路 LED均流控制电路， 其特征在于， 包括： 恒流源、 多个 LED 支路、 每个 LED支路对应一个控制电路；
每个所述控制电路包括： 驱动电阻和 PNP管；
所述驱动电阻的一端连接对应 LED支路的负端， 另一端连接所述 PNP管 的基极； 每个 LED支路的正端连接所述 PNP管的集电极； 每个 LED支路的 负端接地；
所述 PNP管的发射极通过采样电阻连接恒流源的正端； 每个控制电路中的 PNP管的基极与下一个相邻的控制电路中的 PNP管的 发射极之间连接有反馈电阻， 最后一个控制电路中的 PNP管的基极与第一个 控制电路中的 PNP管的发射极之间连接有反馈电阻。
5、 根据权利要求 4所述的多路 LED均流控制电路， 其特征在于， 每个控 制电路还包括用于修正反馈误差的二极管；
所述二极管与所述的反馈电阻串联，所述的串联支路的负端连接所述 PNP 管的基极， 所述的串联支路的正端连接下一个相邻的控制电路中的 PNP管的 发射极。
6、 根据权利要求 4所述的多路 LED均流控制电路， 其特征在于， 每个控 制电路还包括用于修正反馈误差的修正电阻和修正 NPN管；
所述修正电阻的一端连接所述控制电路中的 PNP管的基极， 另一端连接 修正 NPN管的发射极；
修正 NPN管的集电极连接所述恒流源的正端， 基极通过反馈电阻连接下 一个相邻的控制电路中的 PNP管的发射极。
7、 一种多路 LED均流控制电路， 其特征在于， 包括： 恒流源、 多个 LED 支路、 每个 LED支路对应一个控制电路；
每个所述控制电路包括： 驱动电阻和 NMOS管；
所述驱动电阻的一端连接对应 LED支路的正端， 另一端连接所述 NMOS 管的栅极； 每个 LED支路的正端连接所述恒流源的正端；
所述 NMOS管的源极通过采样电阻连接所述恒流源的负端， 漏极连接对 应 LED支路的负端；
每个控制电路中的 NMOS管的栅极与下一个相邻的控制电路中的 NMOS 管的源极之间连接有反馈电阻， 最后一个控制电路中的 NMOS管的栅极与第 一个控制电路中的 NMOS管的源极之间连接有反馈电阻。
8、 一种多路 LED均流控制电路， 其特征在于， 包括： 恒流源、 多个 LED 支路、 每个 LED支路对应一个控制电路；
每个所述控制电路包括： 驱动电阻和 PMOS管；
所述驱动电阻的一端连接对应 LED支路的负端， 另一端连接所述 PMOS 管的栅极；每个 LED支路的正端连接所述 PMOS管的漏极，每个 LED支路的 负端接地；
所述 PMOS管的源极通过采样电阻连接恒流源的正端；
每个控制电路中的 PMOS管的栅极与下一个相邻的控制电路中的 PMOS 管的源极之间连接有反馈电阻， 最后一个控制电路中的 PMOS 的栅极与第一 个控制电路中的 PMOS管的源极之间连接有反馈电阻。
PCT/CN2011/074775 2010-06-01 2011-05-27 一种多路led均流控制电路 WO2011150772A1 (zh)

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