LMR33630AP-Q1: LMR33630APAQRNXRQ1 power supply issue

Ankur Patel

Part Number: LMR33630AP-Q1
Other Parts Discussed in Thread: LMR33630

Hi,
I am using LMR33630APAQRNXRQ1 for 3.8V@3A. Mistakenly did not connect PGND to GND, I have connected it through external wire to GND.
Now the supply is coming for sometimes and all of sudden Vout is getting 0V. I have changed IC few times on different boards but same problem is there. I've observred that in IC there is Internal regulator of 5V which is coming on VCC pin of IC, it is getting drop to 1.65V.

Waiting for your promt response.

Attaching schematics for reference.

9 months ago

0 Naresh Adepu 9 months ago

TI__Mastermind 19820 points

Thanks Ankur for your question. I will look into it and get back to you

Thanks and Regards

Naresh

0 Ankur Patel 9 months ago in reply to Naresh Adepu

Prodigy 10 points

Thank you,
I have taken waveform of SW and BOOT pin also.
Please check if it is correct or not.
Note : Red waveform is BOOT & Blue waveform is SW.

0 Naresh Adepu 9 months ago in reply to Ankur Patel

TI__Mastermind 19820 points

Hi Ankur,

thanks for your question. I will look into it and get back to you

Thanks and Regards

Naresh

0 Naresh Adepu 9 months ago in reply to Naresh Adepu

TI__Mastermind 19820 points

thanks for your patience Ankur. I will get back to you by tomorrow.

0 Naresh Adepu 9 months ago in reply to Naresh Adepu

TI__Mastermind 19820 points

Thanks Ankur,

The issue is caused by PGND not being connected directly and locally to GND at the IC. Using an external wire introduces voltage drop and noise, so the IC’s internal 5V VCC falls to 1.65V and it shuts down, causing Vout to drop. The SW and BOOT waveforms confirm abnormal switching due to loss of proper ground reference. Please ensure PGND and AGND are tied together at the IC with short, wide local copper pour - do not use external wires. This will restore correct VCC operation and stable switching per datasheet guidelines.

Thanks and Regards

Naresh

0 Ankur Patel 9 months ago in reply to Naresh Adepu

Prodigy 10 points

Thanks Naresh,
Will do the necessary changes in layout.
I have one more question: if the ICs shut down because of an improper connection, is there a chance they will function again?

0 Naresh Adepu 9 months ago in reply to Ankur Patel

TI__Mastermind 19820 points

Thanks Ankur. I will get back to you

0 Naresh Adepu 9 months ago in reply to Naresh Adepu

TI__Mastermind 19820 points

Hi Ankur,

Yes, if the LMR33630 IC only shut down due to a temporary improper ground or VCC connection, it should work normally again after fixing the layout and restoring proper grounding. As long as the IC wasn’t exposed to overvoltage, excess current, or prolonged faults, its undervoltage lockout and protection features allow recovery without lasting damage. If repeated severe faults occurred, then replacement may be necessary

Thanks,

Naresh

0 Ankur Patel 9 months ago in reply to Naresh Adepu

Prodigy 10 points

Thanks Naresh,
Will check.

0 Naresh Adepu 9 months ago in reply to Ankur Patel

TI__Mastermind 19820 points

Okay Ankur. thank you

Simulation, hardware & system design tools

Simulation, hardware & system design tools forum

LMR33630AP-Q1: LMR33630APAQRNXRQ1 power supply issue