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AM5728: Pullup/pulldown questions

yf liao
Expert 1080 points
Part Number: AM5728

Hi, in PinMux if one pin's pull up/down is checked:

1. what's the value of this pull up/down resistor?  What's the difference from the resistor calculated from "IN with pull down enabled" or "IIN with pull up enabled" in datasheet section 5.7?

2.  when will those pull up/down resistor take effective? After POR or after software has configured that pin?

3. If one pin works as output, is that internal pull down/up resistor still exist?



  • 0
    TI__Guru**** 393215 points

    Hi,

    1. The resistor value can be calculated according to Ohm's law:

    Rpulldown = VDDSHVx / IIN with pulldown enabled
    Rpullup = VDDSHVx / IIN with pullup enabled

    2. After the pin is configured by software, except in cases where the pullup/pulldown is enabled at reset release time. See Table 4-2 in the datasheet.

    3. Yes, but there is normally no need to enable it.

  • 0 in reply to Biser Gatchev-XID
    Expert 1080 points

    Hi Basier,

    1.  For those pins enter  PD  state after POR release, their resistor value is same as what you calculated in answer 1, and they actually take effective  prior to software take control ? please confirm.

    3. if above is true , then for those pins work as output, or have external pull resistor placed  in circuit, no need to check  the pull settings in PINMUX, is that correct?

  • 0 in reply to yf liao
    TI__Guru**** 393215 points

    1. Yes.

    3. Yes.