LM2576 fault problem

litingkun

LM2576 fault problem [Copy link]

 

I used LM2576s-5 to connect such a circuit, 24V input converted to 5V/500mA. After connected, the LED light can be turned on. The output voltage is also normal 5.1V. But after plugging and unplugging the input power cord several times, the light will not light up. And the interface will spark a little when plugging and unplugging. It is soldered on a perforated board. The chip is from a certain treasure. After it does not light up, unplug the input power, use a multimeter to measure the conduction gear to measure the input or output and ground. At first, the buzzer will sound for about 3 seconds, and then it will stop. Can anyone tell me which component is the problem? (The ss14 picture is upside down)

maychang

It's impossible to tell which component is faulty.

However, SS14 is not drawn upside down, the direction in the picture is correct.

溯歌09

There is no problem with the principle. The direction of SS14 is correct. You can check whether the soldering of components is wrong.

tagetage

At the beginning, the buzzer will sound for about 3 seconds and then stop - the capacitor still has power.

qwqwqw2088

I suspect the plug is broken.

I measured the input and output, and what was the result? No output voltage?

qwqwqw2088

The conventional circuit should be like this

How can plugging and unplugging cause damage? Check where the welding is wrong, such as cold soldering.

huo_hu

Look at the waveform of pin 2

soso

Did you solve the problem? Please give me a reply.

litingkun

soso posted on 2022-3-15 11:38 Did you solve the problem? Please give me a reply.

Solved, the chip or something was burned. Just changed the parts and re-soldered it.