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TMP400: about remote sensing of TMP400

Part Number: TMP400

Hi dear supporting team,

customer is using TMP400 in below way:

1. one chip has remote pins D+, D- floating, sometimes they will get "OPEN" bit as 0, sometimes it will be 1, from d/s, it seems if not use remote control, we need short D+,D- in case of fault alert.  so is this normal? 

2.  for another chip, they connect it to remote sensor of PMBT3904,  they find one chip will sometimes report 113degree when the temp actually be 60degree. from the transistor d/s, there is no resistance spec which request in our d/s P19, so could you pls help comment whether  it is  matching to our spec requirement?

tks a lot!

  • Hi Vera,

    If the D+ and D- pins are left floating the OPEN status should be detected and a '1' should be seen in the register as long as the ADC attempts to convert a remote temperature.  If customer is not converting a remote temperature reading this will not be seen as a 1.  Please short these pins together if they are not being used.

    The temperature reading on that transistor is not expected to be that far off from the actual temperature.  A series resistor may be necessary for increased accuracy, but this is setup specific.  Please see FILTERING section on page 18 of the datasheet for more details. 

    Thanks,