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Original question:

DP83825I: Internall PU, PD values and strap resistor value

DP83825I: HSDC045 Rev B

Harsha K
Prodigy 180 points
Part Number: DP83825I


Tool/software:

Hi,

Regarding the Boot strap

from the above for the default options "0", does need to add PD resistor 2.49K or is the internal pull-down resistor is sufficient, In the HSDC045 Rev B schematic, only pull up options are provided.

and also, is LED_0 pin capable of driving LED, is below circuit acceptable ?

Regards,

Harsha

  • 0
    TI__Mastermind 40545 points

    Hi Harsha,

    The PD resistor should be enough to initialize the pin so long as nothing else in the node is altering (ie loading from the SoC). The PD is recommended atleast as a placeholder in case, but the critical functionality can be done with the weaker internal PD. A DC measurement of the node at strapping time would yield whether or not the external resistor is required for your circuit.

    LED pins should be capable of driving the circuit below in 3.3V condition. For 1.8V, extra circuitry may be required to compensate for the LED turn-on voltage.

    Sincerely,
    Gerome