LM3671: LM3671MF-1.8/NOPB output defect

MJ Jeon

Part Number: LM3671

Hi,

In the circuit below, it replaced the LM3671MF-1.8 in place of the existing SC189 and occurred during the function test.

[Defect symptom]
The output was lowered to 0.8V or less when the power was turned on during the test by installing it in the place of U16 of the above circuit.
It does not recover automatically and returns to normal output (1.8V) after reset.

The bad symptoms did not occur again afterwards.

[condition]
Vin: DC 5V
Vout: DC 1.8V
Iout: about 70mA (only used for memory power)

What is the cause of this defect?

In order to apply it as a replacement product, it is intended to accurately determine the cause of the defective symptom.
Take good care of me.

Thanks.

Regards,

over 3 years ago

0 Excel Regidor over 3 years ago

TI__Mastermind 30346 points

Hello MJ,

Apology for the late response.

The output voltage (1.8V) dropped to 0.8V or less after power-up. It will return to its nominal value (1.8V) only after resetting the supply voltage. Is my understanding correct?

I need to additional information to better understand the issue.

1. Can you share a waveform (VIN, Vout, inductor current) when the voltage drop to 0.8V?

2. When you change with a new device, does the Vout still drop 0.8V or less?

Best regards,

Excel

0 MJ Jeon over 3 years ago in reply to Excel Regidor

Genius 5240 points

Hi, Excel

What you understand is correct.

1. No defect occurred after 1 time.

2. The same defect did not occur when changing to a new part.

Are there cases where the same symptom may occur due to a one-time defect?

Thanks.

Regards,

0 Excel Regidor over 3 years ago in reply to MJ Jeon

TI__Mastermind 30346 points

Hi MJ,

Thanks for the update.

I have not encountered where the output voltage does not regulate to its target level. Did you place the "bad" part on a good board and check the issue still persist? If it is, then I suggest sending the device to your local TI team for failure analysis.

Best regards,

Excel

0 Excel Regidor over 3 years ago in reply to Excel Regidor

TI__Mastermind 30346 points

Hi MJ,

Have you send the "bad" part for failure analysis?

Best regards,

Excel

0 Excel Regidor over 3 years ago in reply to Excel Regidor

TI__Mastermind 30346 points

Hi MJ,

Just a soft reminder.

Did you send the "bad" part in TI for failure analysis?

Best regards,

Excel

0 MJ Jeon over 3 years ago in reply to Excel Regidor

Genius 5240 points

Hi, Excel

As mentioned earlier, bad symptoms have not occurred after one episode.

The customer has not yet received a request for analysis on defective products, so we cannot send it.

We will respond again after re-inquiring with the customer.

Thanks.

Regards,

0 Excel Regidor over 3 years ago in reply to MJ Jeon

TI__Mastermind 30346 points

Hi MJ,

Noted. I will close this thread in the meantime. And you can re-open it again by adding your comments.

I hope it is ok with you.

Best regards,

Excel

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LM3671: LM3671MF-1.8/NOPB output defect