Self-adaptation LED current ripple canceling circuit

Abstract

The invention provides a self-adaptation LED current ripple canceling circuit. The circuit comprises a power tube Q108, a current sampling resistor R109, an operational amplifier U110 and a self-adaptation reference voltage generating circuit. A drain electrode of the power tube Q108 is connected to a negative electrode of an LED load, and a source electrode of the power tube Q108 is connected to one end of the current sampling resistor R109, the inverting input end of the operational amplifier U110 and the input end of the self-adaptation reference voltage generation circuit; the output end of the self-adaptation reference voltage generating circuit is connected to the non-inverting input end of the operational amplifier U110. The output end of the operational amplifier U110 is connected with a grid electrode of the power tube Q108. The other end of the current sampling resistor R109 serves as the grounding end of the self-adaptation LED current ripple canceling circuit. The self-adaptation reference voltage generating circuit is used for automatically adjusting output voltage according to sampling voltage and controlling the operational amplifier U110 so as to control the working state of the power tube Q108 to transfer to a saturation region from a linear region. The circuit is used for canceling LED frequency flickering.

Description

technical field [0001] The invention relates to an illumination drive circuit, in particular to an LED constant current drive circuit. Background technique [0002] LED is a typical current-mode device, which requires high stability of working current. A simple schematic diagram of a traditional LED constant current drive circuit is shown in figure 1 As shown, it includes AC input source, rectifier bridge, constant current drive module, filter capacitor and LED load, and the LED load and filter capacitor are directly connected in parallel. [0003] In order to meet the requirement of high power factor, the current output by the above-mentioned constant current drive module contains power frequency ripple components. Contains 100Hz ripple. At the same time, the current flowing through the LED load also contains 100Hz ripple, which causes the light output by the LED load to contain 100Hz flicker. Although it is difficult for the naked eye to perceive this low-frequency fli...

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Problems solved by technology

At the same time, the current flowing through the LED load also contains 100Hz ripple, which causes the light output by the LED load to contain 100Hz strobe

Although it is difficult for the naked eye to perceive this low-frequency flicker, the human eye will be exposed to this lighting environment for a long time, which will cause visual nerve fatigue and endanger human health. In 2010 and 2013, IEEE proposed the potential health effects of LED lighting flickering. Hazards, such as photosensitive epilepsy, migraine, vertigo, etc., so the call for flicker-free LED lighting is growing

Moreover, a large current ripple will affect the luminous efficiency of the LED and shorten its service life

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