CN201839487U - LED multi-channel constant-current control circuit - Google Patents

Abstract

A LED multi-channel constant current control circuit, including a voltage detection circuit connected in sequence, a voltage reference circuit, a signal comparison circuit and a control signal output circuit, the voltage detection circuit includes a resistor 1, diodes and capacitors corresponding to LED tubes or LED tube groups respectively 2. The voltage reference circuit includes a resistor 3, a resistor 4, and a capacitor 3. The signal comparison circuit includes a capacitor 4, a capacitor 5, a resistor 5, and an operational amplifier or includes a diode 3, a resistor 7, and a comparator integrated circuit. The control signal output circuit includes a resistor 6. . The utility model realizes the steady flow by adopting the method of improving the efficiency of the linear series steady flow circuit, and has the advantages of high steady flow efficiency, wide steady flow range, linear steady flow, no EMC interference, simple circuit, flexible application and the like.

Description

A LED multi-channel constant current control circuit

technical field

The utility model relates to an LED control circuit, in particular to an LED multi-channel constant current control circuit.

Background technique

LED light-emitting diodes have the characteristics of high luminous efficiency, energy saving and environmental protection, and have been widely used in lighting fixtures.

Usually, an LED lamp needs to be composed of multiple LED tubes connected in series and in parallel. Due to the discrete characteristics of the parameters of the LED tubes, when the same current is passed, the voltage drop of each LED tube is different. When the same voltage is applied to the LED tubes, the working current of each LED tube is different. When multiple tubes are used in series, the discreteness of each string of LED tubes is greater. As a result, when the same voltage is used to drive the series LED tubes, the working current of each string of LED tubes is very different. Too large current will not only increase power consumption , And it brings the temperature of LED tube to rise, and the life is shortened.

The ideal driving method of LED light-emitting diodes is constant current driving to solve the above problems. With constant current drive, each string of LED tubes requires a constant current source.

The existing constant current source for driving LED lamps usually adopts the following structure: One solution is to use the output of the constant voltage source to stabilize the current through linear series to generate a constant current source. The solution is low in cost, and the EMC (ElectroMagnetic Compatibility) is simple to deal with, but the efficiency is low and the steady current range is low. Another solution is to use a constant voltage source to output a constant current source after being stepped down by a BUCK circuit or boosted by a BOOST circuit. This solution has high efficiency and a wide range of steady current, but the circuit is complex, the reliability is low, the EMC interference is great, it is very difficult to deal with, and the cost is also high.

Utility model content

The technical problem to be solved by the utility model is to provide a multi-channel constant current control circuit for LEDs, which can be used in conjunction with a constant current source generated by a constant voltage source output through a linear series of constant currents, so as to overcome the problems of existing multi-channel constant current sources for LED lamps. The aforementioned defects of the circuit.

The technical solution adopted by the utility model to solve the technical problem is: to construct a LED multi-channel constant current control circuit, which is characterized in that it includes a voltage detection circuit connected in sequence, a voltage reference circuit, a signal comparison circuit and a control signal output circuit;

The voltage detection circuit includes a resistor 1, a diode corresponding to the LED tube or LED tube group and a capacitor 2, one end of the capacitor 2 is grounded, the other end is connected to the resistor 1, and the other end of the resistor 1 is connected to the previous constant voltage source Or the auxiliary power supply VCC of the subsequent constant current source, the positive terminals of the diodes are respectively connected to the connection terminals of the resistor 1 and the capacitor 2, and the negative terminals of each diode are connected to its corresponding LED tube or LED tube group ;

The voltage reference circuit includes a resistor 3, a resistor 4, and a capacitor 3, the capacitor 3 is connected to both ends of the resistor 4 in parallel, the resistor 3 and the resistor 4 are connected in series, and the resistor 4 is connected to the ground, and the resistor 3 is connected to the previous constant voltage High-precision reference voltage for the source or post-stage constant current circuit;

The signal comparison circuit includes a capacitor 4, a capacitor 5, a resistor 5 and an operational amplifier, and the capacitor 4 is connected in parallel to the two ends of the capacitor 5 connected in series with the resistor 5 to form a negative feedback network, and one end of the negative feedback network is connected to The output end of the operational amplifier and the other end are connected to the inverting input end of the operational amplifier, and the non-inverting input end of the operational amplifier is connected to the connection end of the resistor 1 and the capacitor 2 of the voltage detection circuit, the inverting The input end is connected to the serial connection end of the resistor 3 and the resistor 4 of the voltage reference circuit, or the inverting input end of the operational amplifier is connected to the connection end of the resistor 1 and the capacitor 2 of the voltage detection circuit, The non-inverting input end is connected to the serial connection end of the resistor 3 and the resistor 4 of the voltage reference circuit;

Or the signal comparison circuit includes a diode 3, a resistor 7 and a comparator integrated circuit, the two ends of the diode 3 and the resistor 7 are connected in series to form a hysteresis circuit, and the anode end of the diode 3 in the hysteresis circuit is connected to the comparator The output terminal of the integrated circuit of the comparator, the other end of the hysteresis circuit is connected to the non-inverting input terminal of the integrated circuit of the comparator, and the non-inverting input terminal of the integrated circuit of the comparator is connected to the resistor 1 and the capacitor 2 of the voltage detection circuit The connecting end and the inverting input end of the voltage reference circuit are connected in series with the resistor 3 and the resistor 4;

The control signal output circuit includes a resistor 6, one end of the resistor 6 is connected to the output end of the operational amplifier or comparator integrated circuit, and the other end is an output end.

In the LED multi-channel constant current control circuit of the present utility model, the control signal output circuit includes a diode 4, and the resistor 6 is connected in series with the diode 4; when the non-inverting input terminal of the operational amplifier is connected to the voltage detection circuit When the connecting end of the resistor 1 and the capacitor 2 is connected, the positive end of the diode 4 is connected to the output of the operational amplifier; when the inverting input of the operational amplifier is connected to the voltage detection circuit When the connection terminal of the resistor 1 and the capacitor 2 is connected, the negative terminal of the diode 4 is connected to the output terminal of the operational amplifier; when the non-inverting input terminal of the comparator integrated circuit is connected to the resistor 1 of the voltage detection circuit When connecting with the capacitor 2, the positive terminal of the diode 4 is connected to the output terminal of the comparator integrated circuit.

In the LED multi-channel constant current control circuit of the present invention, the voltage detection circuit includes a capacitor 1 and a resistor 2, the capacitor 1, the resistor 2 and the capacitor 2 form an RC filter circuit, and the capacitor 1 and the capacitor 2 are commonly grounded , the connecting end of the capacitor 1 and the resistor 2 is connected to the non-inverting input end or the inverting input end of the operational amplifier or the non-inverting input end of the comparator integrated circuit.

Implementing the LED multi-channel constant current control circuit of the present utility model, compared with the prior art, its beneficial effects are:

1. The highest efficiency of the LED multi-channel constant current control circuit of the utility model is higher than that of the existing BUCK or BOOST constant current source; the experiment proves that the utility model minimizes the linear adjustment by adopting the method of improving the efficiency of the linear series constant current circuit The tube-to-ground voltage can be controlled at a minimum of 0.1V, and the efficiency is higher than that of the switching regulator circuit. For example, if the voltage is stabilized from 12V to 11.9V, the efficiency can reach 99.1%, and the efficiency can reach 99.1% if the voltage is stabilized from 53V to 52.9V. Up to 99.98%.

2. It has the advantages of wide steady current range of BUCK or BOOST constant current source, and can stabilize the current well and efficiently within 20% of the output voltage change;

3. It has the advantages of linear steady flow and no EMC interference;

4. The circuit is simple and the application is very flexible.

Description of drawings

The utility model will be further described below in conjunction with accompanying drawing and embodiment, in the accompanying drawing:

Fig. 1 is a circuit diagram of an embodiment of the utility model LED multi-channel constant current control circuit.

Fig. 2 is a circuit diagram of another embodiment of the LED multi-channel constant current control circuit of the present invention.

Fig. 3 is a circuit diagram of another embodiment of the LED multi-channel constant current control circuit of the present invention.

Fig. 4 is a circuit diagram of the utility model LED multi-channel constant current control circuit when its control signal output circuit is connected to the constant voltage source voltage feedback control loop of the previous stage and the circuit diagram is used.

Fig. 5 is a circuit diagram of the utility model LED multi-channel constant current control circuit in the application of an optocoupler whose control signal output circuit is connected to the previous stage constant voltage source voltage feedback control loop.

Fig. 6 is a complete application diagram of the wiring of the voltage detection circuit of the LED multi-channel constant current control circuit of the present invention.

Detailed ways

As shown in FIG. 1 , the LED multi-channel constant current control circuit 100 of the present invention includes a voltage detection circuit 10 , a voltage reference circuit 20 , a signal comparison circuit 30 and a control signal output circuit 40 connected in sequence.

The voltage detection circuit 10 includes a resistor R1, diodes D1, D2...DN, capacitors C1, C2, and a resistor R2. One end of resistor R1 is connected to the auxiliary power supply VCC of the previous stage constant voltage source or the rear stage constant current source, and the other end is connected to capacitor C2. Capacitors C1, C2 and resistor R2 form an RC filter circuit. Capacitors C1 and C2 are commonly grounded. Capacitor C1 and resistor R2 The connection terminal leads to the output terminal of the voltage detection circuit 10, and the positive terminals of the diodes D1, D2...DN are respectively connected to the connection terminal of the resistor R1 and the capacitor C2, and the negative terminal is connected to the corresponding LED tube or LED tube group LED1, LED2...LEDN.

In other embodiments, a capacitor can be used to replace the above-mentioned RC filter circuit, that is, the voltage detection circuit 10 includes a resistor R1, diodes D1, D2...DN, and a capacitor C2, and one end of the resistor R1 is connected to the previous constant voltage source Or the auxiliary power supply VCC of the rear stage constant current source, the other end is connected to the capacitor C2, and the capacitor C2 is grounded. The extreme ends are respectively connected to the connecting end of the resistor R1 and the capacitor C2, and the negative end is connected to the corresponding LED tube or LED tube group LED1, LED2...LEDN.

The voltage reference circuit 20 includes a resistor R3, a resistor R4 and a capacitor C3. Capacitor C3 is connected to both ends of resistor R4 in parallel. After resistor R3 and resistor R4 are connected in series, resistor R4 is grounded, and resistor R3 is connected to the high-precision reference voltage VREF of the previous stage constant voltage source or the rear stage constant current circuit. Resistor R3 and resistor R4 The connection end leads out to the output end of the voltage reference circuit 20 .

The signal comparison circuit 30 includes a capacitor C4, a capacitor C5, a resistor R5 and an operational amplifier U1-A. Capacitor C4 is connected in parallel to both ends of capacitor C5 and resistor R5 in series to form a negative feedback network, one end of the negative feedback network is connected to the output terminal (pin 1) of operational amplifier U1-A, and the other end is connected to operational amplifier U1-A the inverting input (pin 2). The non-inverting input terminal (pin 3) of the operational amplifier U1-A is connected to the output terminal of the voltage detection circuit 10, that is, the connection terminal connected to the resistor R2 and the capacitor C1 of the voltage detection circuit 10 (when the voltage detection circuit 10 adopts an RC filter circuit) Or connect the connection terminal of the resistor R1 and the capacitor C2 (when the voltage detection circuit 10 uses a capacitor instead of the RC filter circuit), the inverting input terminal (pin 2) of the operational amplifier U1-A is connected to the output terminal of the voltage reference circuit 20 , that is to connect the series terminal of the resistor R3 and the resistor R4 of the voltage reference circuit 20 .

The control signal output circuit 40 includes a resistor R6 and a diode D4', and the resistor R6 is connected in series with the diode D4'. The positive terminal of diode D4' is connected to the output terminal (pin 1) of operational amplifier UI-A.

As shown in Figure 2, in other embodiments, the inverting input terminal (pin 2) of the operational amplifier U1-A of the signal comparison circuit 30 is connected to the output terminal of the voltage detection circuit 10, that is, connected to the resistor R2 of the voltage detection circuit 10 The connection terminal with the capacitor C1 (when the voltage detection circuit 10 uses an RC filter circuit) or the connection terminal connecting the resistor R1 and the capacitor C2 (when the voltage detection circuit 10 uses a capacitor instead of the RC filter circuit), the operational amplifier U1-A The non-inverting input end (pin 3) of the voltage reference circuit 20 is connected to the output end of the voltage reference circuit 20, that is, the serial connection end of the resistor R3 and the resistor R4 of the voltage reference circuit 20 is connected. At this time, the diode D4' of the control signal output circuit 40 is negative The purpose of the present invention can also be achieved by connecting the terminal to the output terminal (pin 1) of the operational amplifier UI-A.

As shown in Fig. 3, in other embodiments, the signal comparison circuit 30 includes a diode D3', a resistor R7' and a comparator integrated circuit U5-A. Diode D3' and resistor R7' are connected in series to form a hysteresis circuit (to prevent misoperation of the comparator integrated circuit U5-A), and the anode end of the diode D3' in the hysteresis circuit is connected to the output terminal of the comparator integrated circuit U5-A (reference pin 1), the other end of the hysteresis circuit is connected to the noninverting input terminal (pin 3) of the comparator integrated circuit U5-A, and the noninverting input terminal of the comparator integrated circuit U5-A is connected to the output terminal of the voltage detection circuit 10, that is, connected The connection terminal between the resistor R2 and the capacitor C1 of the voltage detection circuit 10 (when the voltage detection circuit 10 adopts an RC filter circuit) or the connection terminal connecting the resistor R1 and the capacitor C2 (when the voltage detection circuit 10 adopts a capacitor instead of the RC filter circuit) ), the inverting input terminal (pin 2) of the comparator integrated circuit U5-A is connected to the output terminal of the voltage reference circuit 20, that is, the serial connection terminal of the resistor R3 and the resistor R4 of the voltage reference circuit 20 is connected. At this time, the positive terminal of the diode D4' of the control signal output circuit 40 is connected to the output terminal (pin 1) of the comparator integrated circuit U5-A.

As shown in Figure 4, when the output terminal of the control signal output circuit 40 is connected to the voltage stabilizing reference (pin 5 of the operational amplifier U2-B of the previous stage) of the previous stage constant voltage source voltage feedback control loop, the control signal output circuit 40 must The resistor R6 is connected in series with the diode D4'.

In other embodiments, as shown in FIG. 5 and FIG. 6, when the output terminal of the control signal output circuit 40 is connected to the optocoupler OT1-B, the control signal output circuit 40 can omit the diode D4', that is, the control signal output circuit 40 only A resistor R6 is used.

The parameters of the resistors, capacitors, diodes, operational amplifiers, and comparator integrated circuits in the above embodiments can be determined and selected according to the prior art.

As shown in Figure 6, the constant current source 110 is composed of an operational amplifier U4 with a reference, a current detection resistor RS1, a voltage regulator Q1 and its surrounding resistive capacitors. Pin 3 of the operational amplifier U4 outputs a 2.5V reference voltage. The constant current source 120 is composed of an operational amplifier U3 with a reference, a current detection resistor RS2, a voltage regulating tube Q2 and surrounding resistive capacitor devices, and pin 3 of the operational amplifier U3 outputs a 2.5V reference voltage. The constant current sources 110, 120 drive LED2, LED1 respectively.

Claims (3)

1. A kind of LED multi-channel constant current control circuit, is characterized in that, comprises the voltage detection circuit that is connected successively, voltage reference circuit, signal comparison circuit and control signal output circuit; The voltage detection circuit includes a resistor 1, a diode corresponding to the LED tube or LED tube group and a capacitor 2, one end of the capacitor 2 is grounded, the other end is connected to the resistor 1, and the other end of the resistor 1 is connected to the previous constant voltage source Or the auxiliary power supply VCC of the subsequent constant current source, the positive terminals of the diodes are respectively connected to the connection terminals of the resistor 1 and the capacitor 2, and the negative terminals of each diode are connected to its corresponding LED tube or LED tube group ; The voltage reference circuit includes a resistor 3, a resistor 4, and a capacitor 3, the capacitor 3 is connected to both ends of the resistor 4 in parallel, the resistor 3 and the resistor 4 are connected in series, and the resistor 4 is connected to the ground, and the resistor 3 is connected to the previous constant voltage High-precision reference voltage for the source or post-stage constant current circuit; The signal comparison circuit includes a capacitor 4, a capacitor 5, a resistor 5 and an operational amplifier, and the capacitor 4 is connected in parallel to the two ends of the capacitor 5 connected in series with the resistor 5 to form a negative feedback network, and one end of the negative feedback network is connected to The output end of the operational amplifier and the other end are connected to the inverting input end of the operational amplifier, and the non-inverting input end of the operational amplifier is connected to the connection end of the resistor 1 and the capacitor 2 of the voltage detection circuit, the inverting The input end is connected to the serial connection end of the resistor 3 and the resistor 4 of the voltage reference circuit, or the inverting input end of the operational amplifier is connected to the connection end of the resistor 1 and the capacitor 2 of the voltage detection circuit, The non-inverting input end is connected to the serial connection end of the resistor 3 and the resistor 4 of the voltage reference circuit; Or the signal comparison circuit includes a diode 3, a resistor 7 and a comparator integrated circuit, the two ends of the diode 3 and the resistor 7 are connected in series to form a hysteresis circuit, and the anode end of the diode 3 in the hysteresis circuit is connected to the comparator The output terminal of the integrated circuit of the comparator, the other end of the hysteresis circuit is connected to the non-inverting input terminal of the integrated circuit of the comparator, and the non-inverting input terminal of the integrated circuit of the comparator is connected to the resistor 1 and the capacitor 2 of the voltage detection circuit The connecting end and the inverting input end of the voltage reference circuit are connected in series with the resistor 3 and the resistor 4; The control signal output circuit includes a resistor 6, one end of the resistor 6 is connected to the output end of the operational amplifier or comparator integrated circuit, and the other end is an output end. 2. The LED multi-channel constant current control circuit according to claim 1, characterized in that: the control signal output circuit includes a diode 4, and the resistor 6 is connected in series with the diode 4; when the non-inverting input of the operational amplifier When the terminal is connected to the connection terminal of the resistor 1 and the capacitor 2 of the voltage detection circuit, the positive terminal of the diode 4 is connected to the output terminal of the operational amplifier; when the inverting input terminal of the operational amplifier is connected to the When connecting the resistor 1 and the capacitor 2 of the voltage detection circuit, the negative terminal of the diode 4 is connected to the output terminal of the operational amplifier; when the non-inverting input terminal of the comparator integrated circuit is connected to the voltage When detecting the connection terminal of the resistor 1 and the capacitor 2 of the circuit, the positive terminal of the diode 4 is connected to the output terminal of the comparator integrated circuit. 3. The LED multi-channel constant current control circuit according to claim 1 or 2, wherein the voltage detection circuit includes a capacitor 1 and a resistor 2, and the capacitor 1, resistor 2 and capacitor 2 constitute an RC filter circuit, The capacitor 1 and the capacitor 2 are commonly grounded, and the connecting terminal of the capacitor 1 and the resistor 2 is connected to the non-inverting input terminal or the inverting input terminal of the operational amplifier or the non-inverting input terminal of the comparator integrated circuit.

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