CN201904959U - LED drive circuit with long service life - Google Patents

Abstract

The utility model relates to a long-lived LED drive circuit, which comprises: a rectifier bridge circuit (1), which rectifies the AC power supply into a DC input; : a low voltage reference module (3), which outputs a constant low voltage as a reference voltage; a sampling resistor circuit (4), which generates a constant current through the reference voltage, and controls the current flowing through the LED light-emitting circuit to be a constant current; the LED voltage limiting circuit ( 5), limiting the voltage drop on the LED lighting circuit; the feedback constant current adjustment circuit (6), when the load of the LED drive circuit changes, maintains the constant current through the feedback control sampling resistor circuit (4), so as to keep flowing through the LED The current of the light emitting circuit (2) is a constant current. The long-life LED drive circuit adopts a constant low voltage as a reference to realize constant current, and reduces the voltage drop on the LED light-emitting element, and keeps the current of the LED light-emitting element constant through feedback, thereby realizing a voltage-limited constant-current drive power supply to meet the requirements of the LED light-emitting element. Longevity driven requirements.

Description

A long-life LED drive circuit

technical field

The utility model relates to LED lighting technology, in particular to a long-life LED lighting driving circuit.

Background technique

LED (Light Emitting Diode) is a light-emitting diode, which uses a solid semiconductor chip as a light-emitting material. When a forward voltage is applied to both ends, the carriers in the semiconductor recombine, and excess energy is released to cause photon emission to produce visible light.

LED lighting has many advantages, including: high efficiency and energy saving; the light does not contain infrared and ultraviolet radiation; the light does not flicker, which is beneficial to the health of eyesight; it relies on low-voltage DC drive, which is suitable for battery and solar power supply; high safety factor; high light efficiency, Less fever, wait. Therefore, with the maturity of technology, LED lighting has been widely used. Replacing existing energy-saving lamps with LED lighting has become a development trend at home and abroad.

In terms of the life of LED lighting products, the current life of LED, that is, light-emitting diode itself, has theoretically reached 100,000 hours. However, LED has very strict requirements on its power drive circuit, so the reliability and lifespan of LED lighting products are directly determined by the condition of the LED drive circuit. Experiments have proved that only under the premise that the driving circuit maintains a high-precision constant current and voltage limit can the LED ensure uniform brightness and long-term reliable operation.

However, in existing LED lighting products, it is common that the power drive circuit cannot stably realize constant current and voltage limitation, resulting in accelerated light decay, shortened lifespan and even damage to the LED. Although the performance of the power drive circuit of high-end LED lighting products is relatively stable, it needs to use a dedicated chip to control the power supply, and the cost is high, so it is not popularized and applied. Therefore, there is an urgent need for an LED driving circuit capable of stably realizing constant-current and voltage-limited power supply while maintaining low cost in existing LED lighting products.

Utility model content

Aiming at the above-mentioned various defects of the existing LED drive circuit, the utility model provides an improved long-life LED drive circuit, which uses low voltage as a reference, effectively reduces the voltage drop of the LED light-emitting circuit, and can provide stable power through feedback. Constant current, thereby realizing the voltage limitation and constant current power supply of the LED light-emitting circuit, achieving the purpose of making the LED light-emitting circuit long-lived, and keeping the cost low.

The long-lived LED drive circuit of the present utility model comprises: a rectifier bridge circuit (1), which rectifies the AC power supply into a DC input; and an LED light-emitting circuit (2), which is composed of several groups of LEDs (LED1-LED4) connected in series; it is characterized in that, Also includes:

A low voltage reference module (3), which outputs a constant low voltage as a reference voltage;

The sampling resistance circuit (4) generates a constant current through the reference voltage, and controls the current flowing through the LED lighting circuit to be a constant current;

The LED voltage limiting circuit (5) limits the voltage drop on the LED lighting circuit;

The feedback constant current adjustment circuit (6) maintains the constant current through the feedback control sampling resistance circuit (4) when the load of the LED driving circuit changes, so as to keep the current flowing through the LED light emitting circuit (2) at a constant current.

Preferably, wherein, the sampling resistor circuit (4) includes a parallel circuit of first and second sampling resistors (R6, R7); the LED voltage limiting circuit (5) includes first and second voltage dividing resistors (R4 , R5) and the third voltage dividing resistor (R2); and, the reference voltage output terminal of the low voltage reference module (3) is connected to the parallel connection of the first and second voltage dividing resistors (R4, R5) Circuit; the parallel circuit of the first and second voltage dividing resistors (R4, R5) is connected in series with the parallel circuit of the first and second sampling resistors (R6, R7), and passes through the third voltage dividing resistor (R2) The DC input connected in series to the rectifier bridge circuit (1) reduces the voltage drop on the LED lighting circuit (2) through the first and second voltage dividing resistors (R4, R5) and the third voltage dividing resistor (R2). And, wherein, the reference voltage output by the low voltage reference module (3) is 1.24V. Still further preferably, the low-voltage reference module (3) is TL432 (U1), and the reference pole of TL432 (U1) is used as a reference voltage output terminal.

Preferably, the feedback constant current adjustment circuit is a MOSFET transistor (Q1), and the D pole of the MOSFET transistor (Q1) is connected to the negative pole of the LED lighting circuit 2, and the positive pole of the LED lighting circuit (2) is connected to the rectifier bridge circuit (1 ) DC input; the S pole of the MOSFET transistor (Q1) is grounded through the parallel circuit of the first and second sampling resistors (R6, R7); the G pole of the MOSFET transistor (Q1) is connected to the low voltage reference Module (3) constitutes a feedback loop.

The utility model adopts the constant low voltage of the low-voltage reference module as a reference to realize constant current, reduces the voltage of the sampling resistance circuit, and reduces the voltage drop on the LED light-emitting element by adjusting the voltage-dividing resistance value of the LED voltage-limiting circuit. Keep the current of the LED light-emitting element constant, so as to realize the voltage-limited constant-current driving power supply, and meet the requirements of long-life driving of the LED light-emitting element.

Description of drawings

FIG. 1 is a schematic diagram of a circuit structure of a long-life LED driving circuit according to an embodiment of the present invention.

Detailed ways

In order to describe the technical content, structural features, achieved goals and effects of the present utility model in detail, the following will be described in detail in combination with specific implementation methods and accompanying drawings.

FIG. 1 is a schematic diagram of a circuit structure of a long-life LED driving circuit according to an embodiment of the present invention. As shown in FIG. 1 , the long-life LED drive circuit includes a rectifier bridge circuit 1 composed of a rectifier bridge D2 and capacitors C1 and C2 for rectifying AC power into DC input. The LED driving circuit also includes an LED lighting circuit 2, which is made up of several groups of LEDs connected in series. For example, the LED lighting circuit 2 shown in FIG.

The long-life LED driving circuit uses a constant low voltage as a reference voltage to realize constant current. As shown in Fig. 1, the low voltage reference module 3 outputs a constant low voltage as a reference voltage. In this embodiment, the module can use TL432 chip U1. The TL432 chip is a voltage stabilizing chip commonly used in the field, and its reference pole can output a constant low voltage of 1.24V. In this embodiment, the positive pole of the TL432 chip U1 is grounded, and the negative pole is connected to the DC output of the rectifier bridge circuit 1 through a resistor R1 and a diode D1 , the reference pole is used as the reference voltage output terminal, so that a constant low voltage of 1.24V is used as the reference voltage to generate a constant current on the sampling resistor circuit. Compared with the 2.4V voltage provided by TL431 commonly used in the prior art in this field as a reference voltage, the utility model uses a constant low voltage of 1.24V as a lower reference voltage, which effectively reduces the voltage on the sampling resistor circuit.

The sampling resistor circuit 4 generates a constant current through the reference voltage, and controls the current flowing through the LED lighting circuit 2 to be a constant current. The sampling resistor circuit 4 includes a parallel circuit of the first sampling resistor R6 and the second sampling resistor R7. Since the reference voltage is constant, the current flowing through R6 and R7 is a constant current, so that the current flowing through the LED lighting circuit 2 is also constant current. The LED voltage limiting circuit 5 is used to limit the voltage drop on the LED lighting circuit; the LED voltage limiting circuit 5 includes a parallel circuit of a first voltage dividing resistor R4, a second voltage dividing resistor R5 and a third voltage dividing resistor R2. As shown in Figure 1, the reference voltage output terminal of the low voltage reference module 3 is connected to the parallel circuit composed of the first and second voltage dividing resistors R4 and R5; the parallel connection of the first and second voltage dividing resistors R4 and R5 The other end of the circuit is connected in series with the parallel circuit of the first and second sampling resistors R6 and R7, and connected in series to the DC input of the rectifier bridge circuit 1 through the third voltage dividing resistor R2. Therefore, by rationally designing the resistance values of the first and second voltage dividing resistors R4, R5 and the third voltage dividing resistor R2, the voltage drop on the LED light-emitting circuit 2 can be controlled and reduced, thereby satisfying the voltage-limited driving necessary for LED longevity requirements.

When the load of the LED driving circuit changes, the feedback constant current adjustment circuit 6 controls the sampling resistor circuit 4 through a feedback loop to maintain the constant current, so as to keep the current flowing through the LED lighting circuit 2 at a constant current, thereby achieving a more stable constant current drive. As shown in Figure 1, the feedback constant current adjustment circuit is a MOSFET transistor Q1, and the D pole of the MOSFET transistor Q1 is connected to the negative pole of the LED lighting circuit 2, and the positive pole of the LED lighting circuit 2 is connected to the DC input of the rectifier bridge circuit 1; MOSFET three The S pole of the stage transistor Q1 is grounded through the parallel circuit of the first and second sampling resistors R6 and R7; the G pole of the MOSFET transistor Q1 is connected to the negative pole of the TL432 of the low voltage reference module 3 to form a feedback loop. Q1 maintains a certain conduction state. When the load of the LED drive circuit changes, the feedback obtained from the sampling resistor circuit 4 also changes, resulting in a change in the conduction state of Q1 for feedback adjustment, so that the first and second sampling resistors The electric current of R6, R7 keeps constant. Therefore, the LED lighting circuit 2 can obtain a constant current value, which will not be affected by changes in the load and voltage value, forming a high-precision constant current source.

The longevity LED drive circuit of the utility model realizes high-precision constant current and voltage-limited driving through the lower reference voltage of TL432 and the feedback constant current adjustment circuit, and has the following advantages: it provides resistance step-down constant The current drive circuit and high-precision constant current power supply ensure the life of the LED light-emitting components; the LED drive circuit has no electrolytic capacitors, and all devices can reach a working life of nearly 100,000 hours. The bridge rectifier supports AC and DC power supply, and there is no direction requirement ; The accuracy of the constant current is within 1%, fully satisfying the driving characteristics of the LED, and suitable for replacing the existing products on the market.

The above is only an embodiment of the utility model, and does not limit the patent scope of the utility model. Any equivalent structure or equivalent process conversion made by using the utility model specification and accompanying drawings, or directly or indirectly used in other Related technical fields are all included in the patent protection scope of the present utility model in the same way.

Claims (5)

1. long-lived led drive circuit comprises:

Rectifier circuit (1) is the direct current input with the Alternating Current Power Supply rectification, and

LED illuminating circuit (2) is made up of the some groups of LED (LED1-LED4) that connect;

It is characterized in that, also comprise:

Low-voltage base modules (3) is exported constant low-voltage as reference voltage;

Sample resistance circuit (4) produces constant current by described reference voltage, and control flows is a constant current through the electric current of LED illuminating circuit;

LED pressure limiting circuit (5), the pressure drop on the restriction LED illuminating circuit;

Circuit (6) is adjusted in the feedback constant current, when the load variations of led drive circuit, keeps described constant current by FEEDBACK CONTROL sample resistance circuit (4), is constant current with the electric current of the LED illuminating circuit (2) that keeps flowing through.

2. long-lived led drive circuit according to claim 1 is characterized in that, described sample resistance circuit (4) comprises the parallel circuits of first, second sample resistance (R6, R7); Described LED pressure limiting circuit (5) comprises the parallel circuits and the 3rd divider resistance (R2) of first, second divider resistance (R4, R5); And the reference voltage output end of described low-voltage base modules (3) connects the parallel circuits of described first, second divider resistance (R 4, R5); The parallel circuits of first, second divider resistance (R4, R5) is connected with the parallel circuits of described first, second sample resistance (R6, R7), and be connected serially to the direct current input of described rectifier circuit (1) by described the 3rd divider resistance (R2), reduce pressure drop on the LED illuminating circuit (2) by first, second divider resistance (R4, R5) and the 3rd divider resistance (R2).

3. long-lived led drive circuit according to claim 2 is characterized in that, the reference voltage of described low-voltage base modules (3) output is 1.24V.

4. long-lived led drive circuit according to claim 3 is characterized in that, described low-voltage base modules (3) is TL432, and the reference utmost point by TL432 is as reference voltage output end.

5. long-lived led drive circuit according to claim 2, it is characterized in that, it is MOSFET triode (Q1) that circuit is adjusted in described feedback constant current, and the D utmost point of MOSFET triode (Q1) connects the negative pole of LED illuminating circuit 2, and the positive pole of LED illuminating circuit (2) connects the direct current input of described rectifier circuit (1); The S utmost point of MOSFET triode (Q1) is by the parallel circuits ground connection of described first, second sample resistance (R6, R7); The G utmost point of MOSFET triode (Q1) is connected to described low-voltage base modules (3) and constitutes feedback loop.

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