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TMP464: remote temperature test

Janice yi
Prodigy 10 points
Part Number: TMP464

Hi All,

I'm an ICT engineer and I'm handling a project that required to test TMP464 remote temperature.

- How is the connection for remote temperature?

- should I just follow the BJT, Rs1, Rs2 and Cdiff connection as below photo?

- i have N3906 PNP transistor, 1K resistor, 1000pF capacitor, is it ok to use in this connection?

Thank you,

Regards,

Janyi

  • +1
    TI__Mastermind 41325 points

    Hi Janyi,

    Your resistor and capacitor values are high, but still supported by the specification. Note that resistance RS1 + RS2 is summed for the purposes of TMP464's series resistance specification. Resistance and capacitance are not necessary for operation and can be omitted. In Figure 6, resistance is tested with zero capacitance. In Figure 7, capacitance is tested with zero resistance. The combination of too much R+C will cause the error shown in Figure 7 to occur at lower capacitances. 

    Our official recommendations are in Figure 20 notes.

    thanks,

    ren

  • 0 in reply to Ren Schackmann
    Prodigy 10 points

    Hi Ren,

    ok got it, so i will remove the resistor and capacitor.

    i will just use 2N3906 and wire base on the datasheet typical application.

    next in order to read the remote temperature data output,

    i will follow the figure 16, pointer to hex 01. then the data output will be the remote temperature 1 value.

    correct me if im wrong.

    Thanks,

    Janyi

  • 0 in reply to Janice yi
    Prodigy 10 points

    Hi,

    Why my data is 1000 0000 0000 0000 when using BJT 2N3906 as remote temperature.

    Thanks,

    Janyi

  • 0 in reply to Janice yi
    TI__Mastermind 41325 points

    Janice,

    This result suggests the 2N3906 is not connected. If you read register 0x23, it will likely report the remote channels as OPEN. Did you accidentally disconnect your 2N3906 by removing the resistors?

    thanks,

    ren

  • 0 in reply to Ren Schackmann
    Prodigy 10 points

    Hi Ren,

    i think i have found the problem, I'm using relay for switching the BJT to the board signal,

    after i remove the relay and direct wire to the board, it works fine.

    thank you so much for the help!

    Regards,
    Janyi