TPS40322EVM-074: TPS40322 EVM has negative voltage in VIN ON/OFF

Rock Shao

Part Number: TPS40322EVM-074
Other Parts Discussed in Thread: TPS40322

Hi E2E team,

My customer tested the TPS40322 EVM and found there has a negative voltage of about -250mV in the following test item.

1. OLP test, C1(yellow): Vin, 12Vdc, C2(red): Vout, used a short probe to test TP7 & TP22, found output voltage has a negative voltage

2. Vin ON/OFF test, C1(yellow): Vin, 12Vdc, C2(red): Vout, used a short probe to test TP7 & TP22, found output voltage has a negative voltage

3. EN ON/OFF test (output add Switch), C1 (yellow): Vin, 12Vdc, C2(red): Vout, used a probe test output terminal, found output voltage has a negative voltage

Load 0A

Load 30A

Are the above waveforms normal? thanks.

Regards

Rock

over 4 years ago

0 Matt Schurmann over 4 years ago

TI__Genius 11095 points

Hello, Are you using an electronic load for this test? It is not uncommon to see a similar effect due to energy storage in the inductance of the wires which connect the EVM board to the electronic load. Can you re-try the test with a resistor load?

0 Rock Shao over 4 years ago in reply to Matt Schurmann

Expert 2985 points

Hello,

My customer used electronic load for this test.

0 Rock Shao over 4 years ago in reply to Rock Shao

Expert 2985 points

Hi Matt,

Did you have any idea about TPS40322 EVM has a negative voltage issue? thanks.

0 Matt Schurmann over 4 years ago in reply to Rock Shao

TI__Genius 11095 points

Hi Rock, Can you ask them to try it with a resistor load soldered on the board (no long wires)? I think this is just an artifact of the measurement methodology.

0 Chasel Chen over 4 years ago

TI__Expert 5830 points

Hi Rock,

This thread will be closed because we did not hear you for a while.

Thanks

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TPS40322EVM-074: TPS40322 EVM has negative voltage in VIN ON/OFF