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DP83TD510E: Strap resistor value range

Cyrus Kelly
Prodigy 240 points
Part Number: DP83TD510E

Hello,

How much flexibility in the value used for the strap resistor?  Would it be OK to use a 3.0K, 2.7K, 2.2K, 2.0K, 1.8K etc.?

Thanks,

Cyrus

  • 0
    TI__Mastermind 39835 points

    Hi Cyrus,

    Please refer to table 7-5 of the datasheet. You must use 2.49kOhms, 1% tolerant resistors.

    Sincerely,

    Gerome

  • 0 in reply to Gerome Cacho
    Prodigy 240 points

    Hello,

    I did refer to table 7-5.  It says, "IDEAL RESISTORS" which implies that other values may be used.  Can you please double check this?  Requiring different exact resistor values that are very close to the same value adds extra components to the BOM and drives product cost up.  If I could use even a 2.2K or 2.7K instead it would be very helpful.

    Thanks,

    Cyrus

  • 0 in reply to Cyrus Kelly
    TI__Mastermind 39835 points

    Hi Cyrus,

    I understand where you are coming from. The value is important to be close to as this external resistor connection completes a voltage divider circuit. When the PHY boots up, it samples the strapping pins to see which mode it will be in per strapping pin (in this case, mode 0 or mode 1). By attaching a different resistor value than what is provided in the datasheet, the voltage on that node may be different than what the PHY is expecting, which may cause it to bootup in a different mode than what you intend it to be. This problem becomes more apparent in our other PHYs which have 4 level straps (therefore a tighter window to be in). We cannot guarantee intended operation if you deviate from these values. 

    Sincerely,

    Gerome