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"Auto" configuration for the AFE4490?

Ed Hepler
Expert 1940 points
Other Parts Discussed in Thread: AFE4490

Does TI have an app note that describes any method for "auto" configuration of the AFE4490?

I'm looking for a way to set LED1/LED2 levels, gain levels, ambient DAC value, etc. automatically, perhaps by periodically running an algorithm that "senses" various parameters available from the chip and calculating what the "best" TX and RX parameters should be.   I would assume that the sampling rate (PRP) would be set by the user.

Thanks!

  • 0
    TI__Mastermind 49186 points
    Hello Ed,

    Currently there is no app note that describes the auto configuration for AFE4490.

    Here is a brief procedure to do the gain and LED configuration manually.

    1) At first, run the system with lowest gain (Rf = 10K) and low LED current (ILED = 2mA). Disable the stage 2. Measure the DC and AC in the ADC output.
    2) If the AC value is not reasonable good, Increase the LED current or Rf setting such that DC becomes half of the ADC full scale. This will increase the AC signal also.
    3) If the AC value is still not sufficient, then enable stage and cancel the extra DC current (but ensure that the data in the ambient phase is not saturated)
    4) The Cf value can be set such that the TIA time constant is much lower than the LED pulse width.