WO2012006847A1

WO2012006847A1 - Light emitting diode (led) lamp drive circuit

Info

Publication number: WO2012006847A1
Application number: PCT/CN2010/079219
Authority: WO
Inventors: 段卫垠; 熊林生; 汪本强
Original assignee: 深圳市航嘉驰源电气股份有限公司
Priority date: 2010-07-13
Filing date: 2010-11-29
Publication date: 2012-01-19
Also published as: CN201869400U

Abstract

A light emitting diode (LED) lamp drive circuit is disclosed, which forms multiplex constant current and uniform current circuits by using a constant current source and multiplex current mirror circuits. The LED lamp drive circuit includes the constant current source, a constant current drive circuit, a sampling circuit, at least one way load circuit, and a current mirror circuit correspondingly connected with the load circuit, wherein the load circuit is connected with the power supply in parallel, the sampling circuit is used for collecting a voltage of the current mirror circuit logic combination, the constant current drive circuit is connected with the sampling circuit and the current mirror circuit, and controls the current mirror circuit performing the uniform current adjusting according to the voltage collected by the sampling circuit. The LED lamp drive circuit controls the current mirror circuit performing the uniform current adjusting through collecting the voltage of the current mirror circuit logic combination, which can meet the high uniform current precision and improve the drive efficiency, and its circuitry is simple and price is low.

Description

LED light drive circuit

Technical field

The present invention relates to the field of driving circuit technologies, and in particular, to an LED lamp driving circuit.

Background technique

With the intensification of the world energy crisis, reducing energy consumption and protecting the environment have become a consensus. LED lighting will replace the first- and second-generation lighting technologies with low energy efficiency. For LED lighting, TI, ONSEMI, PI and other companies have developed many products. The circuit topology includes BUCK, BOOST, FLYBACK, LLC, and linear steady current. The technologies used include the following two:

(1) Current mode PWM control technology, by directly sampling the current of the series LED, comparing the sampling current with the reference voltage, and adjusting the duty ratio according to the comparison result, thereby controlling the operating current of the LED.

(2) Linear steady current technology, by directly sampling the current of the series LED, comparing the sampling current with the reference voltage, and adjusting the on-resistance of the steady flow tube according to the comparison result, thereby controlling the working current of the LED.

Existing high-power LED lighting lamps generally use multiple LEDs in series, and each string of LEDs needs a corresponding constant current source for separate driving. Therefore, when multiple strings of LEDs are operated in parallel, a corresponding number of constant current sources are required to supply power. Moreover, each constant current source must independently perform current sampling, and the power consumption of the sampling resistor will increase, and the design of multiple constant current sources also increases the cost. If a constant current source and multiple current mirror circuits are used to form a multi-channel constant current sharing circuit, the design can be simplified, but the power consumption of the current sharing circuit cannot be controlled.

Summary of the invention

The main object of the present invention is to provide an LED lamp driving circuit aimed at reducing the cost of the LED lamp driving circuit and improving the driving efficiency.

The invention provides an LED lamp driving circuit, comprising: a constant current source, a constant current driving circuit, a sampling circuit, at least one load circuit and a current mirror circuit correspondingly connected to the load circuit, wherein the load circuit is connected in parallel with the power source; The sampling circuit is configured to collect a voltage of a logical combination of the current mirror circuits; the constant current driving circuit is connected with the sampling circuit and the current mirror circuit, and controls the current mirror circuit to perform current sharing adjustment according to the voltage collected by the collecting circuit.

Preferably, the current mirror circuit includes a switch tube correspondingly connected to the load circuit, the drain of the switch tube is connected to the load circuit, and the gate is connected to the constant current drive circuit, and the load circuit is controlled according to the constant current drive circuit. Perform current sharing adjustment.

Preferably, the voltage of the logical combination of the current mirror circuits collected by the acquisition circuit includes a minimum voltage, an average voltage or a maximum voltage.

Preferably, the constant current driving circuit includes an operational amplifier, the non-inverting input terminal of the operational amplifier is connected to the sampling circuit, the inverting input terminal is connected to the source of the switching tube, and the output end is connected to the gate of the switching tube; The operational amplifier generates an output signal according to the positive phase input terminal signal and the inverting input terminal signal, and controls the current mirror circuit to perform current sharing adjustment on the load circuit.

Preferably, the constant current driving circuit further includes a feedback resistor and a voltage dividing resistor, one end of the feedback resistor is connected to the output end of the operational amplifier, and the other end is connected to the inverting input terminal of the operational amplifier; one end of the voltage dividing resistor and the feedback The resistor and the inverting input of the operational amplifier are connected, and the other end is connected to the source of the switching transistor.

Preferably, the feedback resistor and the voltage dividing resistor are both adjustable resistors.

Preferably, the above-mentioned switching transistor MOSFET transistor or BIPOLAR transistor.

Preferably, the above load circuit comprises at least two LEDs connected in series.

The LED lamp driving circuit of the invention can control the current mirror circuit to perform current sharing adjustment by collecting the voltage of the logic combination circuit of the current mirror circuit, so as to meet the high current sharing precision and improve the driving efficiency. Moreover, the line is simple and the price is low.

DRAWINGS

1 is a schematic structural view of an embodiment of an LED lamp driving circuit of the present invention;

2 is a schematic diagram showing the circuit structure of an embodiment of an LED lamp driving circuit of the present invention;

3 is a schematic diagram showing the output characteristics of the switch tube related to the LED lamp driving circuit of the present invention;

4 is an experimental report of a switch tube in an LED lamp driving circuit of the present invention;

5 is a schematic circuit diagram of an embodiment of an LED lamp driving circuit of the present invention;

Fig. 6 is a view showing simulation results of the LED lamp driving circuit in the above embodiment.

The implementation, functional features, and advantages of the present invention will be further described in conjunction with the embodiments.

detailed description

It is understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.

BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 is a block diagram showing an embodiment of an LED lamp driving circuit of the present invention.

In the LED driving circuit of the embodiment, a constant current source and a multi-channel current mirror circuit are used to form a multi-channel constant current equalizing circuit, including a constant current source 10, a constant current driving circuit 20, a sampling circuit 30, at least one load circuit 40, and a load. Circuit 40 corresponds to a connected current mirror circuit 50. The multi-way load circuit 40 is connected in parallel with the constant current source 10. The sampling circuit 30 is for collecting the voltage of the logical combination of the current mirror circuits 50. The constant current driving circuit 20 is connected to one of the load circuit 40 and the sampling circuit 30, and controls the current mirror circuit 50 to perform current sharing adjustment according to the voltage collected by the sampling circuit 30.

2 is a circuit configuration diagram of an LED lamp driving circuit of the present invention. In the LED lamp driving circuit of this embodiment, the load circuit 40 is three paths.

The current mirror circuit 50 includes a switch tube that is connected to the load circuit 40. The drain of the switch is connected to the load circuit 40, and the gates are connected to the constant current drive circuit 20. The load circuit 40 is subjected to current sharing regulation according to the control of the constant current drive circuit 20. The switching transistor is preferably a transistor (eg, a MOSFET transistor, a BIPOLAR transistor). The switching transistor 21 of this embodiment is a MOSFET, such as the first MOSFET Q1, the second MOSFET Q2, and the third MOSFET Q3 in FIG. The switch tube includes a gate, a drain and a source. The gate of the switching transistor is connected to the output terminal of the constant current driving circuit 20, and the drain is connected to the load circuit 40.

The voltage combination of the logic mirror circuit 50 collected by the sampling circuit 30 described above includes a minimum voltage, an average voltage or a maximum voltage.

The constant current driving circuit 20 includes an operational amplifier X1, a feedback resistor R2, and a voltage dividing resistor R3. The operational amplifier X1 The non-inverting input is connected to the drain of the switch, and the inverting input is connected to the feedback resistor R2 and the voltage dividing resistor R3. Operational Amplifier X1 According to the positive phase input terminal signal and the inverting input terminal signal, an output signal is generated and output to the gate of the switch tube, and the control switch tube performs current sharing adjustment on the load circuit 40. One end of feedback resistor R2 and op amp X1 The output is connected and the other end is connected to the inverting input of the operational amplifier X1 for negative feedback of the operational amplifier X1 to achieve constant current driving of the load circuit 40. Voltage divider resistor R3 One end is connected to the source of the switch, and the other end is connected to the feedback resistor R2 and the inverting input of the operational amplifier X1. The operational amplifier X1, the feedback resistor R2, and the voltage divider resistor R3 It can constitute a minimum power consumption constant current drive control circuit.

The above constant current source can also be replaced by a constant voltage source, and the constant voltage source can achieve the same effect as the constant current source according to the impedance characteristic of the load, and provides a constant current for the load.

Figure 3 is a graph showing the output characteristics of a MOSFET. The MOSFET is referenced to the switch of the Philips model BSH105. As can be seen from FIG. 3, the ID current of the switch BSH105 is controlled by VGS, where VGS is the voltage between the source and the gate of the switch BSH105. When the VGS is 1.1V, its ID current is constant, about 0.3A. VDS is the voltage between the drain and the source of the switching transistor BSH105, which can be varied within a voltage range of 0.5V to 2V. Moreover, the higher the VDS, the greater the loss of the switching tube.

Since the VGSs of the switching tubes corresponding to the multiple load circuits 40 are equal in this embodiment, the current flowing through the switching tubes is also equal. Therefore, the total current I provided by the constant current source 10 will be an average of 3 parts, respectively flowing through the corresponding switching tubes of each of the load circuits 40. When I is 1.05A, the current ID of the switch corresponding to each load current 40 is 350mA. Therefore, by adjusting the ratio of the feedback resistor R2 and the voltage dividing resistor R3, the size of the switching transistor VGS is adjusted to meet the accuracy of the current sharing. The lowest power consumption can be obtained by selecting the largest VDS through the sampling circuit.

4 is an experimental report of a switch tube in an LED lamp driving circuit of the present invention. The switch tube is a switch tube of the BS296 model of Siemens. It can be seen from Fig. 4 that the input voltage is 1.05A in one load and the input current is 1.05A. If the current sharing effect is the best (the load current is 0.363A, 0.353A, 0.343A, respectively), the current error is only 5.51%. . Then the MOSFET has a large loss (the total power consumption of the MOSFET is 0.79W). If the power consumption is minimized (the total power consumption of the MOSFET is 0.499W), the current sharing effect is relatively poor (load current is 0.354A, 0.390A, 0.317A, respectively), and the current error is as high as 18.72%. Therefore, the logic combination of the current mirror circuit collected by the acquisition circuit 30, the feedback resistor R2, and the adjustment of the resistance of the voltage divider resistor R3 can achieve the purpose of better current sharing effect and minimum power consumption.

FIG. 5 is a simulation circuit of the LED lamp driving circuit of the embodiment, and the parameters of the respective components are as shown in FIG. 5.

The impedance difference between the first load circuit and the second load circuit is 220m, and the impedance difference between the load circuit and the third load circuit is 470m. . The switch tube connected to the load circuit is a switch tube of the Philips BSH105 model. The sampling circuit collects the logic combination voltage of the switch tube to be the maximum voltage, that is, collects the voltage VDS of the switch tube corresponding to the first load circuit. Feedback resistor R2 has a resistance of 22K The resistance of the voltage dividing resistor R3 is 10K. The current of the constant current source is 1.05A.

Fig. 6 is a simulation result of the LED lamp driving circuit of this embodiment.

As can be seen from FIG. 6, in the LED lamp driving circuit of this embodiment, the current ID1 of the switching transistor Q1 is 358 mA, and the current ID2 of the switching transistor Q2 is 351. mA, the current ID3 of the switch Q3 is 334 mA. The VDS1 of the switching transistor Q1 is 1V, the VDS2 of the switching transistor Q2 is 0.962V, and the VDS3 of the switching transistor Q3 is 0.928V. Therefore, the power consumption of the switch Q1 is 149.6. mW, the power consumption of the switch Q2 is 131 mW, and the power consumption of the switch Q3 is 115.8 mW.

The above is only the preferred embodiment of the present invention, and is not intended to limit the scope of the invention, and the equivalent structure or equivalent process transformations made by the description of the invention and the drawings are directly or indirectly applied to other related The technical field is equally included in the scope of patent protection of the present invention.

Claims

An LED lamp driving circuit, comprising: a constant current source, a constant current driving circuit, a sampling circuit, at least one load circuit, and a current mirror circuit correspondingly connected to the load circuit, wherein the load circuit is connected in parallel with the power source; The sampling circuit is configured to collect a voltage of a logical combination of the current mirror circuits; the constant current driving circuit is connected with the sampling circuit and the current mirror circuit, and controls the current mirror circuit to perform current sharing adjustment according to the voltage collected by the collecting circuit.
The LED lamp driving circuit according to claim 1, wherein the current mirror circuit comprises a switch tube correspondingly connected to the load circuit, the drain of the switch tube is connected to the load circuit, and the gate is driven by a constant current. The circuit is connected, and the load circuit is subjected to current sharing regulation according to the control of the constant current driving circuit.
The LED lamp driving circuit according to claim 2, wherein the voltage of the logical combination circuit of the current mirror circuit collected by the acquisition circuit comprises a minimum voltage, an average voltage or a maximum voltage.
The LED lamp driving circuit according to claim 2, wherein the constant current driving circuit comprises an operational amplifier, the non-inverting input terminal of the operational amplifier is connected to the sampling circuit, and the inverting input terminal and the source of the switching transistor Connected, the output end is connected to the gate of the switch tube; the operational amplifier generates an output signal according to the signal of the positive phase input terminal and the signal of the inverting input terminal, and controls the current mirror circuit to perform current sharing adjustment on the load circuit.
The LED lamp driving circuit according to claim 3, wherein the constant current driving circuit further comprises a feedback resistor and a voltage dividing resistor, one end of the feedback resistor is connected to the output end of the operational amplifier, and the other end is connected to the operational amplifier. The inverting input is connected; one end of the voltage dividing resistor is connected to the feedback resistor and the inverting input of the operational amplifier, and the other end is connected to the source of the switching transistor.
The LED lamp driving circuit according to claim 5, wherein the feedback resistor and the voltage dividing resistor are both adjustable resistors.
The LED lamp driving circuit according to any one of claims 2 to 6, wherein the switching transistor is a MOSFET transistor or a BIPOLAR transistor.
The LED lamp driving circuit according to any one of claims 1 to 7, wherein the load circuit comprises at least two LEDs connected in series.