AM5728: Pullup/pulldown questions

yf liao

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?

over 6 years ago

0 Biser Gatchev-XID over 6 years ago

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 yf liao over 6 years ago 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 Biser Gatchev-XID over 6 years ago in reply to yf liao

TI__Guru**** 393215 points

1. Yes.

3. Yes.

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AM5728: Pullup/pulldown questions