INN3629C-H606 not switching at start up.

Posted by: Vicenta@987 on 05/05/2025

Hello everyone,

I'm experiencing issues with an INN3629C-H606 IC.

The IC does not switch on at startup, preventing the circuit from functioning.

I've checked all components on the PCB, and they are in good condition.

After replacing the IC, the circuit starts up correctly, indicating that the original IC is likely faulty.

I've desoldered both the faulty and the new ICs and measured the resistance across the pins, but I haven't found any differences or signs of short circuits.

How can I further investigate to determine the cause of the failure?

Thank you in advance for your help.

Comments

Hi Vicenta@987,

Good day. We're sorry to learn ou had issues with the initial start-up.

To further check/ troubleshoot the issue of the board, since you've mentioned that it is not switching we can refer to the device datasheet to review the conditions for the device to start switching. And with this we probe on the switching nodes--on the Drain to Source pin of the device and from this we can verify if it's actually not switching or undergoes to other failure operation such as auto-restarting.

If the condition is confirmed, then we can probe on other parameters stated on the device datasheet page 6-7 if the said conditions were met.

PI-Hueka, thank you for the response.

My question was about how to perform an "internal check" of the IC, as all the conditions for start-up defined in the datasheet were met but there was no initial switching. However, I have found the problem: the pin of the Drain was damaged when it came out of the encapsulation and was not making good contact.

I have added solder to ensure the connection and it is now working correctly.

Thanks again.

Regards.