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AFE4404 two LED mode

Warwick Freeman
Prodigy 70 points

Other Parts Discussed in Thread: AFE4404

I am using an AFE4404 with 3 LEDS.  However I want to run it in two LED mode for oximetry.  The data sheet indicated "When three LEDs are used within a single period, the Ambient2 phase is replaced by the LED3 phase."

How do I disable the third LED from a timing point of view.  Do I set the LED3LEDSTC and LED3LEDENDC registers to 0? so that the sample ambient 2 only has ambient.  I tried the EVM GUI but it does not have samples for 2 LED and 3 LED operation

  • 0
    TI__Guru 50036 points
    Hi Warwick,

    For 2 LED mode, you can set LED3LEDSTC and LED3LEDENDC registers to 0.
    Additionally you can set LED3 current to 0.
    That way, the second phase and the fourth phase will be ambient and first phase and the third phase will be the 2 LED phases.

    The GUI supports 2 LED and 3 LED modes.
    Can you please elaborate on what you mean by there are no samples for 2 LED and 3 LED operation?
  • 0
    Prodigy 70 points
    Thanks that mostly answers my question. What I meant was that I could not see how the GUI provides guidance on 2 or 3 led mode. How does the GUI support 2 LED and 3 LED mode. I can certainly manually put the values you described in the locations but are there examples of a 2 LED and a 3 LED setup?