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TMP461: D+ D- Pins Impedance + Voltage to Counts Transfer Function

Filipe Rubinstein
Prodigy 651 points
Part Number: TMP461

Hi all, 

I hope you are doing well. I have several questions regarding the usage of the TMP461 that I am looking for answers on:

Q1) Does the TMP461 treat the voltage developed between the D+ and the D- pins as a true differential signal implying the D- input is high impedance?  If D- input is low impedance, what is its impedance with respect to GND (pin 6).  If D-  is high impedance what is the maximum & minimum  common mode voltage allowed on D+ and D- ?

Q2) What is voltage to counts transfer function that maps the (assumed differential voltage between) D+ and D-  that corresponds to 0 through full scale A/D counts.

 

Q3) What is minimum bandwidth needed for the A/D to read accurately at each of the 3 measurement currents?

Thank you for your support on this and I hope to hear back from you soon.

  • 0
    TI__Mastermind 35835 points

    Hi Filipe,

    Regarding TMP461, D- is connected internally to GND.

    The currents used in the remote junction measurement are listed in the spec table:

    Figure 6 shows the impact of excessive capacitance:

    We don't disclose further information on the operation of the ADC or bandwidth required.

    thanks,

    ren