Light-emitting diode (LED) switch constant-current driving circuit

Abstract

The invention provides a light-emitting diode (LED) switch constant-current driving circuit. The LED switch constant-current driving circuit comprises a voltage input module, an energy storage inductor, a freewheel diode, an LED module serving a load, a power tube for draining current and constant current, a detection module for detecting an input voltage phase state, a dimming control module connected to the detection module, an error amplifier connected to the dimming control module, a valley bottom detection circuit for detecting power tube drain voltage, a pulse width modulation circuit connected to the error amplifier and the valley bottom detection circuit, a control circuit for controlling the power tube according to detection voltage and PWM signals and a driving circuit of the power tube, wherein according to the dimming control module, input reference voltage Vref2 of the error amplifier and dimming control signals Vdimo are generated jointly through the detection voltage and reference voltage Vref1; the error amplifier enables the Vref2 to be compared with sampling voltage; and the pulse width modulation circuit is used for generating the PWM signals. According to the LED switch constant-current driving circuit, an electrolytic capacitor is not needed, an electronic transformer and a silicon controlled dimmer are compatible, the unique power tube in multiplexing simultaneously gives consideration to the draining current and the constant current, and the cost is effectively reduced.

Description

technical field [0001] The invention relates to the technical field of LED drive control, in particular to an LED switch constant current drive circuit. Background technique [0002] LED is a semiconductor device that works under low-voltage DC conditions. Under the low-voltage AC input conditions of thyristor dimmers and electronic transformers, the market demand for replacing LEDs with existing MR16 applications is very strong. On this basis The demand for compatible SCR dimmers is also considerable in the international market. However, when replacing traditional lighting fixtures such as MR16 with LEDs, some problems will be encountered: [0003] First of all, the compatibility of LEDs and electronic transformers. The current flowing through the electronic transformer must be greater than or equal to its holding current to ensure the stable and reliable operation of the electronic transformer, otherwise the electronic transformer will work intermittently or not, and the...

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Problems solved by technology

[0007] In view of the shortcomings of the prior art described above, the purpose of the present invention is to provide a constant current drive circuit for LED switches, which is used to solve the problem of incompatibility and stability between the LED drive circuit and the thyristor dimmer and electronic transformer in the prior art. Problems such as low cost and high application cost

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