IWR6843AOP: mcu Power short-problem

dave choi

Part Number: IWR6843AOP

Hi there, I'm dave, Hareware engineer.

I would like to ask about iwr6843aop

I designed the circuit using iwr6843aop. 10 PCBs were produced, and 2 MCUs were mounted on one PCB.

But the moment I turned on the power, about 3 out of 10 shorts occurred on the 3.3V or 1.2V line. (I confirmed that the MCU itself was shorted)

PMIC used LP87524JRNFRQ1, 24V to 5V DCDC used LMR33640ADDAR.

I'm not sure where to start, so ask.

I can send you the circuit if you need it.

Where should I check?

Why does the MCU short at 3.3V or 1.2V even though I have a PMIC?

A brief circuit diagram is attached.

PMIC(LP87524JRNFRQ1) is refer to IWR6843AOPEVM Board.

P.S For reference, two MCUs (IWR6843AOP) and two PMICs (LP87524JRNFRQ1) are designed on one PCB. in a dual architecture format.

I will wait for answer.

Best Regards,

Dave.

over 2 years ago

0 Ankit Mohanty over 2 years ago

TI__Genius 9630 points

Hi Dave,

We are looking into your query and will get back to you soon.

Regards

Ankit

0 Ankit Mohanty over 2 years ago in reply to Ankit Mohanty

TI__Genius 9630 points

Hi,

Please send the complete schematic so that we can review it. You can probe along the 3.3V and 1.2V line decaps to check where the short happened.

Regards

Ankit

0 dave choi over 2 years ago in reply to Ankit Mohanty

Prodigy 235 points

Ok thank you. So, where can i send it? can you give me e-mail address?

0 Ankit Mohanty over 2 years ago in reply to dave choi

TI__Genius 9630 points

You can attach the design here.

Regards

Ankit

0 dave choi over 2 years ago in reply to Ankit Mohanty

Prodigy 235 points

I can't do that, cause of confidential, Can you give me e-mail? thanks.

0 Ankit Mohanty over 2 years ago in reply to dave choi

TI__Genius 9630 points

Dave,

We can move this thread to private conversation.

Regards

Ankit

0 dave choi over 2 years ago in reply to Ankit Mohanty

Prodigy 235 points

How can do that? can you do that?

if you can, do it.

and let me know how to attach schematic file with confidential.

P.S I belong to a company, so I have to send it as a secure document

thank you.

0 Ankit Mohanty over 2 years ago in reply to dave choi

TI__Genius 9630 points

Hi Dave,

I verified that the PMIC used is compatible with the IWR6843AOP design, but the TI IWR6843AOP design does not use a DC-DC converter. Please confirm if the dc dc part number is compatible. Please check for overvoltage and probe through the 3.3 and 1.2 V supply lines to determine exactly where the short occurred. Given that every component used in the PMIC is in working order, it is challenging to determine why the short occurred.

Regards

Ankit

0 dave choi over 2 years ago in reply to Ankit Mohanty

Prodigy 235 points

In our system, we need to supply 24v, so we need to use 24v to 5v dcdc. In our system we used the LMR33640ADDAR.
If there is something better suited than this DCDC, please recommend it.

3.3v 1.2v short occurs very rarely, and when it does, the IWR6843AOP MCU dies.
(The fact that the MCU died was actually tested by removing the MCU from the PCB)

I want to check whether the bypass cap is designed incorrectly, so I request a circuit diagram review.

Thanks