IC is easily damaged, but I don't know why. Please help me analyze the reason or make some modifications.

HUhu00

This is a 5V1.5A machine

tagetage

What does T1A T1B mean???

maychang

tagetage posted on 2023-3-31 10:09 What does T1A T1B mean? ? ?

[What does T1A T1B mean? ? ? ]

T1B is another winding on the same core as T1A.

qwqwqw2088

IC is easily damaged for many reasons

See the picture on the first floor

The U1 chip has almost no peripheral protection, and only has a feedback function on the FB pin. Usually, FB generates an error signal as feedback input to the controller by monitoring the output voltage and comparing it with the internal reference voltage, and then monitors and regulates the output voltage.

And this FB is connected to T1B,,,,?

tagetage

Why does this circuit diagram look weird to me? I don't understand the principle. Who designed this diagram?

pcf2000

Without any parameters or models, it is really difficult to analyze...

HUhu00

pcf2000 posted on 2023-3-31 13:17 There are no parameters or models, so it is really difficult to analyze. . .

What information do you need? BOM and circuit have been sent

HUhu00

maychang posted on 2023-3-31 10:36 [What does T1A T1B mean? ? ? ] T1B is another winding on the same core of T1A.

Maychang, could you please help me take a look?

maychang

HUhu00 posted on 2023-3-31 17:22 Can maychang help take a look?

Sorry! I can't figure it out either. I don't know what the reason is.

zhuyu630

The transformer design is most likely to be unreasonable. Ask the chip factory engineer to help you calculate it.

pcf2000

Generally speaking, a power control IC will have a corresponding application circuit, which can be used as a reference. The device must be properly protected, after all, it is a high-voltage circuit. Also, the transformer design is reasonable, the primary side has inductance requirements, and the parameters must be reasonable.

Try to test whether the voltage value of each point is normal, and do the corresponding circuit analysis, you should be able to find the problem.

yyq006

The fault is not only related to the circuit, but also to the PCB routing, especially the FB pin, which has a spacing requirement from the high-voltage part. It is best to contact the chip manufacturer's technical staff to take a look.