Double-circuit complementary linear LED constant current circuit

Abstract

The invention discloses a double-circuit complementary linear LED constant current circuit which comprises a major loop, an output current sampling control loop and a complementary PWM signal input end. The complementary PWM signal input end is used for an external circuit to input mutually-inverted PWM signals. According to the constant current circuit, double-circuit complementary PWM signals are utilized to control two power triodes to be connected in turn and jointly provide a current path for an LED light-emitting unit, compared with a traditional method that just one power triode is used, power consumption of the single triode is reduced by 50%, power supply efficiency is improved, heating is reduced, and safety performance of a lamp is increased; electrolytic capacitance does not exist, cost is low, and service life is long.

Description

technical field [0001] The invention relates to an LED driving circuit, in particular to a dual-channel complementary linear LED constant current circuit. Background technique [0002] At present, for various reasons, many LED lamps use high-voltage and low-current drive schemes. The driving scheme of using traditional transistors in series to achieve linear constant current has the advantages of simple circuit and small size. In this circuit, the power transistor and LED are connected in series. , the divided voltage of the triode will fluctuate accordingly, so the power consumption of the triode will change with the fluctuation of the power supply. In order to further reduce the cost and improve the service life, many circuits do not use electrolytic capacitors for filtering after rectification, so that the voltage at the input terminal will fluctuate greatly, and the triode will withstand the voltage exceeding the LED conduction voltage. When the number of LEDs in series...

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Problems solved by technology

In order to further reduce the cost and improve the service life, many circuits do not use electrolytic capacitors for filtering after rectification, so that the voltage at the input terminal will fluctuate greatly, and the triode will withstand the voltage exceeding the LED conduction voltage. When the number of LEDs in series is small When it is small, the triode consumes a lot of power and generates a lot of heat, which greatly affects the reliability and safety of the circuit.

[0003] At present, household LED lighting drivers tend to be low-cost and miniaturized. Traditional RC step-down is popular, but its inherent defects limit its application in LED lighting. Switching power supply has complex structure, high cost, and is not suitable for high voltage and low current. LED drive; linear power supply has the advantages of simple structure and good electromagnetic compatibility, and is the first choice for high-voltage and low-current drive. However, because the power tube of the linear power supply is connected in series with the LED, the power consumption of the power tube is large, and a large amount of heat is generated. The efficiency of the power supply is reduced, and at the same time, the heat dissipation design difficulty of the lamp is increased, especially when the power of the lamp is small and the number of LEDs connected in series is small, the heat generated by the power tube is huge, and the reliability of the circuit is significantly reduced

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