LED constant-current driving circuit

Abstract

Disclosed in the invention is an LED constant-current driving circuit comprising a first comparator, a second comparator, a first resistor, a first triode and a light-emitting diode group. The light-emitting diode group includes a plurality of light-emitting diodes connected in series; and each light-emitting diode in the light-emitting diode group is connected in parallel with a reversed connected voltage-stabilizing tube. One terminal of the first resistor is connected to an inverted input terminal of the first comparator; and the other terminal is connected with a circuit between an output terminal of the first comparator and a non-inverting input terminal of the second comparator. An output terminal of the second comparator is connected with a base electrode of the first triode; and an inverted input terminal of second comparator is connected with an emitter of the first triode. A direct-current voltage input line and a trigger voltage input line are connected to the first comparator; an output terminal of the light-emitting diode group is connected with a collector of the first triode; and an input terminal of the light-emitting diode group is connected to the direct-current voltage input line. With the structure, the cost is low and the size is small; and reliability of the circuit during application can be improved.

Description

technical field [0001] The invention relates to a driving circuit, in particular to an LED constant current driving circuit. Background technique [0002] LED has the advantages of small size and low cost, so people often use LED for signal detection of some systems, and judge whether the signal in the system is connected by whether the LED light is on during system testing. As a low-voltage, DC semiconductor device, LED needs to work in a constant current environment. Generally, the mains power supply is often used for system power supply. If the LED is required to emit light during system detection, the AC voltage needs to be rectified and controlled by the driving circuit for the LED to use. It can be seen from the electrical characteristics of LEDs that the average forward current of LEDs increases linearly with the increase of forward voltage, and the change of forward voltage of LEDs after forward conduction will cause great changes in the current on LEDs. , and the ...

AI Technical Summary

Problems solved by technology

It can be seen from the electrical characteristics of LEDs that the average forward current of LEDs increases linearly with the increase of forward voltage, and the change of forward voltage of LEDs after forward conduction will cause great changes in the current on LEDs. , and the current has a great influence on the junction temperature of the LED. Excessive current can easily cause the LED to be damaged due to the rise of the junction temperature.

In order to avoid LED damage and affect the accuracy of the test, the existing LED constant current drive circuit has defects such as complex structure, many components, high cost and low reliability.

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