TPS62173: Unstable under both load and no-load conditions

kyle aven88804

Part Number: TPS62173

Hello,

I have a TPS62173 that is being used to power only the digital interface section of two I2C devices. After the devices showed signs of constant POR conditions, I probed the 5V rail produced by the TPS62173 and noticed that it was a saw tooth like waveform.

I then removed the I2C devices the regulator was powering and took the following screenshots:

No load condition

250mA purely resistive load

Schematic clip of device

Suggestions on where to start? The layout if very tight with CIN and COUT very close to the device, SW node is short and wide, VIN and 5V are separate planes, and the board has sufficient ground planes. Nothing else is attached to the VIN rail on these test boards.

Thanks in advance

over 4 years ago

0 JohnTucker over 4 years ago

TI__Guru**** 191445 points

Let me look into this later today.

0 JohnTucker over 4 years ago in reply to JohnTucker

TI__Guru**** 191445 points

Kyle,

Can I see these waveforms dc coupled along with the SW node voltage?

0 kyle aven88804 over 4 years ago in reply to JohnTucker

Prodigy 100 points

John,

It will likely be after the holidays before I can get those waveforms to you. The boards had to be sent to our board house to have all the TPS62173's removed. The problem was damaging the down stream IC's. The only thing the regulator is powering is the digital section of two IRPS5401 regulators. Illustrated below:

0 Jason Wang (BSR-MV) over 4 years ago in reply to kyle aven88804

TI__Genius 9550 points

Kyle,

Just reminder, please upload the waveforms for analysis which mentioned.

0 Jason Wang (BSR-MV) over 4 years ago in reply to Jason Wang (BSR-MV)

TI__Genius 9550 points

Kyle,

We haven’t heard back from you, assume you were able to resolve your issue. If not, just post a reply below (or create a new thread if the thread has locked due to time-out) – thanks

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TPS62173: Unstable under both load and no-load conditions