The LED light bar flickers, which is a very common problem in LED drivers, so let’s first analyze the working principle of LED driver.

The general LED driver circuit using the constant current source control circuit, because the lamp bead a linear relationship between the amount of light and current, there is no change to lamp brightness, constant current.

In other words, when the load resistance value is very high, it needs constant current, so it must increase the output voltage, so that beyond the voltage of the diode, the diode is turned on, and a current flows through the current sampling resistor. That will limit the pressure.

Generally speaking, LED flashing mainly for the following reasons,

1. Sampling current problem, because of the resistance heating, resistance tolerance will have changed, when it gets smaller, that will lead to an increase in output power, which will lead to chip over current protection, there is power protection which will cause flashing. If the sampling resistance increases, the lamp will darken or remain inactive, and the output voltage is important, so the current sampling resistor must have a power margin.

2. There is something wrong with the light board. If the lamp board load does not match, there will also be chip output voltage over voltage, resulting in chip over voltage protection, will lead flashing.

3 The LD input voltage is unstable, that is, the supply voltage of the chip is unstable. If the voltage is not constant, the output voltage and current must be unstable, so the lights will also flash.

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