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TMP117: Hidden Registers

Part Number: TMP117
Other Parts Discussed in Thread: TMP461-SP

Hi,

I recently irradiated several TMP117 parts to xxx Mrad to see whether they would work for an application that requires sterilization. The parts still communicate over I2C but the EEPROM was erased (predictably) and now they read -256.00C and the 3 ID registers are all 0x0.

In my application I could read the EEPROM registers prior to irradiation and then write them back after irradiation. But there appear to be some hidden registers containing calibration values that I can’t read (or write).

Can you please provide information about how to read/write these hidden registers?

Thanks,

Jonathan

  • Dear Jonathan - 

    Thanks for the post. Here we would be unable to provide to you unit specific trim data in that manner - it really would not be scalable. 

    If you need a radiation hardened sensor, please see: https://www.ti.com/product/TMP461-SP 

    and see the https://www.ti.com/product/TMP461-SP#tech-docs section for the radiation testing results. 

    or, you could try a different method of sterilization. (ETO, steam, dry heat, etc.) with the catalog devices. 

  • Josh,

    The space grade TMP461-SP is orders of magnitude too expensive for this application.

    Just to clarify, I am not asking you to provide unit-specific trim data by email or other electronic means. I am asking that you provide information that would help me read that trim data out of the TMP117 chip prior to irradiation so I can save it locally, then write it back to the chip after irradiation. Are you willing to provide that information?

    Jonathan

  • Jonathan - 

    Interacting with the device in this manner is not something we open up for customer use. 

    Furthermore, the immediate observation you have made may not be the only impact. There may be longer term issues started by the exposure that you may not see right away (on the whole system you are making).   

    I would suggest here to choose a different method of sterilization, even though it may require longer time or different handling, I think it may then allow you to meet your cost target, as you mention the application cannot afford a rad-hard sensor.