LM25183-Q1: Flyback power with LM25183-q1 startup failed

yansong.wei

Part Number: LM25183-Q1
Other Parts Discussed in Thread: LM25183

Hi,

Now we use LM25183-Q1 to design flyback power with dual output.

The question is that the power start failed, the output voltage is always 0.

When starts, pin SW has no oscillation switch action, remain high (input voltage: 15V).

What are the possible reasons for this problem？

Thanks.

0 Marshall_Beck over 2 years ago

Hello,

What is the current consumption of the supply ?

Does the issue remain after replacing the device and do you have any waveforms to share?

I will reply with comments on schematic review.

0 yansong.wei over 2 years ago in reply to Marshall_Beck

Thanks, Marshall

We have solved the problem. The pin 8 of LM25183 does not connect to GND, only the thermal pad connect to GND.

And i think this is unreasonable.

+1 Marshall_Beck over 2 years ago in reply to yansong.wei

That is good to hear. Yes, the ground pin and thermal pad are recommended to be connected to the ground net on the PCB.

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