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LMP90099 Datasheet Clarifications

Reagan Revisore
Expert 4225 points

Assuming a setting of both single ended and differential inputs, with 0-5V input range, having an external reference, VA=5V, and VIO=3.3V, could we get clarifications on the following:

  1. If the buffer is OFF, would we still be able to measure thermistors, RTDs, and other high impedance sensors?
  2. Is unipolar measurement only for gains of 8 or below (buffer=Off.) With a gain of 16, there seems to be some overlap in possibilities for the VINN max and VINP min
  3. Would the resolution for a unipolar input of 0-5V just be 23 bits?
  4. What is the wake-up time out of stand-by?
  5. For system calibration, is a full-scale input required throughout? It seems to mention that it  might not be required, and with this in mind, could a gain coefficient be calculated with a 4V reference input, when the plan is ultimately to use 4.99V for the reference?

Any answers that can be provided would be greatly appreciated!

-Reagan

  • 0
    TI__Intellectual 2065 points

    Hi Reagan,

    1. Yes.
    2.Yes, Single ended can be used with gains 8 or less.
    3.Yes.
    4.Can I know what you are refering to ? to get out of stand-by mode you will have to write PWRCN register, there is no automatic timout mode.
    5.Full scale in not needed throught. However chaning the reference at a later point would change the full-scale code. Coefficients has to be recomputed.

    Regards,
    Murali

  • 0 in reply to MS1291
    TI__Expert 4225 points

    Thank you very much for the info here Murali!

    On 4), it's just a question of what the latency might be after writing to the PWRCN register to fully wake-up out of standby.

    -Reagan