DP83867IS: output 50 ohm impedence

David Sandler

Intellectual 1910 points

Part Number: DP83867IS

Hi,

We are intending to use the DP83867ISRGZ in tow of our new designs. According to the datasheet pg. 86, the device has controlled impedance for MAC I/Os. Despite using the term “I/O” I believe this is only available for the MAC outputs:

TX_CTRL

GTX_CLK

TX_D[0:3]

Can you verify if only these signals I have listed include the output 50 ohm impedance?

Thanks,

David

over 8 years ago

0 Rob Rodrigues over 8 years ago

TI__Mastermind 19780 points

Hi David,

You are correct. The adjustable IO impedance is referring to the MAC interface. The GPIO, LEDS, MDIO, RESET, and clock pads are not effected by this adjustable IO impedance.

Best Regards,

0 David Sandler over 8 years ago in reply to Rob Rodrigues

TI__Intellectual 1910 points

Hi Rob,

I am aware that it is only the MAC interface. What is not clear is if the controlled impedance is only on the output signals or both the output and the input signals. A controlled output impedance would look something like this

And a controlled input impedance would look like this

My assumption is that these devices only have controlled OUTPUT impedance, which is why I need clarification

Outputs:

Inputs:

Thanks,

David

0 Rob Rodrigues over 8 years ago in reply to David Sandler

TI__Mastermind 19780 points

Hi David,

The output pins, RX, impedance is adjusted by the programmable terminations.

The input pins, TX, are high impedance at all times and are not controlled by programmable terminations.

Best Regards,

Interface

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DP83867IS: output 50 ohm impedence