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TMP422: Replace TMP421 with TMP422， Tie pin 3/4 of TMP422 to GND, does it work?

ni yong
Prodigy 80 points
Part Number: TMP422
Other Parts Discussed in Thread: TMP421,

Hi

I am using TMP421 as a remote temperature sensor to monitor the ASIC junction temperature. Blow is my schematic design of TMP421.

I want to replace TMP421 with TMP422 without hardware and firmware change, is it workale?

Per datasheet of TMP422, I found If DX3/DX4 are connected to GND, the I2C address is 1001100x, the same as my TMP421 setting address, It looks good for hardware.

Please help me to confirm is there any potential hardware/electrical risk if I directly solder a TMP422 on the TMP421 location in existing product.

Many thanks.

  • 0
    Prodigy 80 points

    Some update for your reference:

    I replaced a TMP421 with TMP422 in one of my PCB, firmware can readout the local sensor and remote 1 sensor through the same I2C address(1001100x),  the replacement looks fully transparent to my firmware code. 

    Thanks.

  • 0 in reply to ni yong
    Prodigy 80 points

    One more question:

    I found there are three part number of TMP422, what is the main different between them? TMP422AIDCN，TMP422AMDCN，TMP422AQDCN.

    I guess they are mainly different with environment and reliability, my product is general commercial grade, can I import all of the three part number into my product?

    Thanks

  • 0 in reply to ni yong
    TI__Mastermind 28070 points

    Hi Ni Yong,

    Thank you for your post and updates. 

    The TMP422 and TMP421 are register map compatible, so this should work as you have noticed. Typically I would recommend disabling the secondary remote channel (REN2 Bit in Configuration register 2) so the TMP422 doesn't waste any time or power trying to perform conversions on the second channel, but this isn't strictly necessary. 

    ni yong said:
    I found there are three part number of TMP422, what is the main different between them? TMP422AIDCN，TMP422AMDCN，TMP422AQDCN.

    The TMP422AQDCN version is the automotive qualified version of the part, and the TMP422AMDCN is our -EP version, which is intended to support hi-reliability applications. For general commercial use I would recommend sticking to the TMP422AIDCN.

    Best Regards,
    Brandon Fisher

  • 0 in reply to Brandon Fisher94
    Prodigy 80 points

    Hi Brandon

    Thanks for your quick response, and I think I got the answer well. 

     

    BRs