LM5143-Q1: VCC can not power on

Miles Yu

Prodigy 20 points

Part Number: LM5143-Q1

Power rail random failed_ No output, failure rate: 4/100

Following waveforms are normal and fail, What condition will cause VCC on output?

[Normal waveform]

[Fail waveform]

over 5 years ago

0 Marshall_Beck over 5 years ago

TI__Mastermind 35210 points

How are you ensuring the absolute maximum input voltage of the device is not being exceeded?

Can you share schematic?

0 Miles Yu over 5 years ago in reply to Marshall_Beck

Prodigy 20 points

The VIN of IC pin is direct from 12-V automotive battery, and we have UVP(6V), OVP (28V)function on the battery side.

The VIN on the waveform is around 12V, no more than the absolute maximum input voltage.

Sorry, we can't post schematic.

I have questions as below
1. What condition can cause VCC no output?
2. Why I just provide VIN=12V (EN=0V) VCC can rise to 1.18V

0 Marshall_Beck over 5 years ago in reply to Miles Yu

TI__Mastermind 35210 points

12V battery can have transients that must be handled to assure device absmax is not exceeded.

Long wires connected to DC/DC can cause inductive ringing that can cause device absmax to be exceeded.

ABSMAX violation I would think would be the number 1 reason for VCC to not be normal value.

Have you been able to capture the failure, with waveforms of both VIN and VCC?

Please send schematic and layout to me at my personal email: m-beck1@ti.com

0 Hsing Shen over 5 years ago in reply to Marshall_Beck

Prodigy 190 points

Why you ask 12V transients problem? We are use power supply for testing/debugging this issue. Not Battery. You can see the Vin max ~13V from the waveform.

The failure waveform of both VIN and VCC already attached before. So we want to know why VCC can't power on while Vin and EN are ready? in the other words, what kind of condition will cause VCC can't power on?

Due to NDA with customer, we can't provide schematic and layout to you. You can check with TI TW FAE Allen(allen_lee@ti.com). Thanks!

Regards,

Hsing

0 Hsing Shen over 5 years ago in reply to Marshall_Beck

Prodigy 190 points

Please see attachment. We list 3 questions and attached waveform for your check.

Regards,

Hsing

V3NP LM5143 power up issues _VCC abnormal.pptx

0 Marshall_Beck over 5 years ago in reply to Hsing Shen

TI__Mastermind 35210 points

I understand the issue with sharing information over public forum.

You can email me at: m-beck1@ti.com

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LM5143-Q1: VCC can not power on