TMP1827: Major delta between sensor and ambient at various frequency

Christina Lim

Expert 6395 points

Part Number: TMP1827

Tool/software:

Hi,

My customer is complaining 2 major issues in their system on TMP1827 :

Major visible difference in the temperature from the sensor and ambiance temperature.
Some time we see -ve values or huge number in between.

1.Major visible difference in the temperature from the sensor and ambiance temperature.

We configured the device for 12 bit precision and getting around 6 Degree Celsius difference from the ambiance temperature.

We tried with 16 bit precision by configuring “Device configuration -1” register for 16 bit but still didn’t see much difference .Below is the screenshot for your reference which we configured.

2.Some time we see -ve values or huge number in between.

To check the validity of the values for the sensor we read the checksum and calculated back to verify. Checksum was good for this -ve and huge values too.

We used the below sequence from the spec for the validation

Thanks,

Christina

over 1 year ago

0 Ren Schackmann over 1 year ago

TI__Mastermind 44025 points

Hi Christina,

Please share schematic and the raw transaction data.

thanks,

ren

0 Christina Lim over 1 year ago in reply to Ren Schackmann

TI__Expert 6395 points

Hi Ren,

I had attached here the draft schematic here for your reference and raw temperature data.

The room temperature was 25 C but temperature sensor was reading 30 to 31 . In between they could see some -ve values too .

raw_temperature_TMP1827.txt

Thanks,

Christina

0 Ren Schackmann over 1 year ago in reply to Christina Lim

TI__Mastermind 44025 points

30 to 31C is expected ambient condition and likely reflects the real localized temperature at the sensor.

You'll have to capture the extreme results on a logic analyzer or oscilloscope for analysis.

thanks,

ren

0 Christina Lim over 1 year ago in reply to Ren Schackmann

TI__Expert 6395 points

Hi Ren,

Customer have developed algorithm to prune out the spikes . But their concern is the temperature deviation . As per the spec, device can expect ±0.9°C (maximum) from –55°C to +150°C for TMP1827N .

Trying to understand is there anything from device side customer can do like HW calibration or anything which can bring the values more closeer to actual temperature.

Thanks,

Christina

0 Ren Schackmann over 1 year ago in reply to Christina Lim

TI__Mastermind 44025 points

Christina,

I don't recommend attempting to filter or calibrate out the data that the customer doesn't like. I suspect that these bad results are communication failures, or that the sensor is somehow being operated in an incorrect manner. I'll need more information to debug the issue.

thanks,

ren

0 Christina Lim over 1 year ago in reply to Ren Schackmann

TI__Expert 6395 points

Hi Ren,

Could you share what are the additional information you need?

Thanks,

Christina

0 Meredith McKean over 1 year ago in reply to Christina Lim

TI__Genius 10090 points

Hello Christina,

Currently Ren is out of office and he plans to return on Monday. In the meantime, you could provide information about how exactly the temperature sensor is used within the system and scope shots of the I2C communication to isolate any software issues.

Best Regards,

Meredith McKean

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TMP1827: Major delta between sensor and ambient at various frequency