Non-strobe isolated LED constant-current driving circuit

Abstract

The invention discloses a non-strobe isolated LED constant-current driving circuit which comprises an alternating-current source, a rectifier bridge, a filtering capacitor, a constant-current driving unit and a strobe eliminating unit. The strobe eliminating unit comprises a reference voltage generation module, a voltage compensation module, a voltage clamping module, a sampling resistor, a switching tube, a sampling capacitor, an operational amplifier and a starting module. According to the LED constant-current driving circuit, currents of the LED driving circuit are controlled, the current of an LED load is made to be equal to a mean value of output currents of the constant-current driving unit, voltage of the switching tube is made to follow a voltage ripple component on the filtering capacitor, thus voltage on the LED load is direct voltage which almost has no ripple, the current on the LED load is a direct current which almost has no ripple, and therefore the purpose that an LED has no strobe is achieved.

Description

technical field [0001] The invention belongs to the technical field of LED constant current drive, and in particular relates to a flicker-free isolated LED constant current drive circuit. Background technique [0002] LED (Light Emitting Diode, Light Emitting Diode) is a typical current-mode device, and its ideal power supply mode is constant current power supply, which requires high stability of working current. The simple schematic diagram of the traditional strobe LED constant current drive circuit is as follows: figure 1 As shown, it includes an AC input source, a rectifier bridge, a constant current drive module 1, a filter capacitor C1 and an LED load, and the LED load and the filter capacitor C1 are directly connected in parallel. The constant current drive module 1 includes: a transformer, a control module 11 , a power tube M, and a resistor R. In order to meet the requirement of high power factor, the current output by the constant current drive module 1 contains ...

AI Technical Summary

Problems solved by technology

At this time, the instantaneous input power P in is the pulsating power in the form of sine square, and the output power P o Is the flat power, the voltage across the LED load can be regarded as a flat voltage, then the current I flowing through the LED load LED There is an AC component of 100Hz in it. The light strobe at this frequency will not only cause human visual nerve fatigue and endanger human health, but also affect the luminous efficiency and color of the LED and shorten the service life of the LED. Therefore, there is an urgent need for a method that can eliminate LED strobe circuit

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