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DP83822HF: About RESET (18pin) and /INT PWDN (8pin)

Tao_2199
Genius 5770 points
Part Number: DP83822HF

Hello,

 

Regarding to DP83822, my customer is asking some question.

 

(Question)

1) About power sequence

When power up, should we need to consider only sequence of VDD and AVD?

(D/S page10)

should we need to consider Center TAP?

2) About RESET (18pin)

If Power Down mode is not used, is there no problem that RESET pin is opened?

3)About /INT PWDN (8pin)

According to D/S page6,it is described as following.

“The pin has an open-drain output with a weak internal pullup. Some applications may require an external pullup resistor.”

In this case, what condition is “some applications”?

(What condition is need external pullup?

Or in what condition is no need external pullup?)

 

Regards,

Tao2199

  • 0
    TI__Mastermind 18425 points
    Hello Tao2199,

    1. Usually center tap is connected to AVD. So Center tap will be powered up with AVD rail.
    2. Reset pin and power down pin are independent of each other. You can choose to connect or disconnect independently.
    3. The power down pin has weak internal pull up. In some cases, power down pin is connected to a MAC which has internal pull-down resistors. This MAC pull down resistor can over-power the PHY pull up resistor and hold the Power Down pin in LOW conditon. When Power Down pin is low, the PHY will enter Power Down Mode. In such cases, external pull up resistor may be required to hold the PHY in active mode for normal operation.

    -Regards,
    Aniruddha