TMP468: Reporting -256 value intermittently 5 out of 1000 reads

Soham Karanjikar

Part Number: TMP468

Hi,

We are using this to sense an OCTS. We get -256 (open) reading intermittently...roughly 5 out of 1000 tries. We are using 4 positions out of the 8. We are testing 4octs, and only see the intermittent fail on site 0 which is D1 on TMP468.

Please let us know why this might be.

Thanks,
Soham

over 2 years ago

0 Nicole Khoury over 2 years ago

TI__Genius 10080 points

Hi Soham,

Thank you for posting to the Sensing forum.

Can you please provide the schematic and a logic analyzer capture of the -256 readings? This will help us to debug the issue further.

Best regards,
Nicole

0 Soham Karanjikar over 2 years ago in reply to Nicole Khoury

Prodigy 70 points

Hi Nicole,

Here is the schematic. The C76, C79, C80, C81 caps have been changed to 0ohm resistors. All diode connections from this page just go to an edge connector pin that is connected to our board where the DUT sits.

0 Soham Karanjikar over 2 years ago in reply to Soham Karanjikar

Prodigy 70 points

As for the logic analyzer capture, I can try to get that next week...however since the fail is so intermittent, it might be hard to. I am also checking the RSOP register to see if that triggers when we get a false read.

0 Nicole Khoury over 2 years ago in reply to Soham Karanjikar

TI__Genius 10080 points

Hi Soham,

I do not see issues with the schematic that you attached, however it does not show the diode connections for each channel. It appears that the TMP468 is detecting an intermittent fault condition on D1; please note that the device will report -256 °C when there is a short-circuit condition detected.

Best regards,

Nicole

0 Soham Karanjikar over 2 years ago in reply to Nicole Khoury

Prodigy 70 points

Hi,

The issue was we were not resetting after measurements, giving us incorrect readings.

Thanks,
Soham

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TMP468: Reporting -256 value intermittently 5 out of 1000 reads