DP83TC814R-Q1: MAC Impedance Control

Jared Becker

Genius 11845 points

Part Number: DP83TC814R-Q1

Hi Team,

Is there a breakdown of how this register corresponds to the impedance for the MAC interface?

For reference, here is what is shown for the 811:

Thank you,

Jared

over 3 years ago

Gerome Cacho over 3 years ago

TI__Mastermind 39855 points

Hi Jared,

I am looking into this. I expect an answer by EoD Friday at the very latest.

Sincerely,

Gerome

Gerome Cacho over 3 years ago in reply to Gerome Cacho

TI__Mastermind 39855 points

Hi Jared,

To control MAC impedances, only bits [0] and [5] control this. They toggle between fast and slow. I am working to get resistance values of these impedances.

Sincerely,
Gerome

Gerome Cacho over 3 years ago in reply to Gerome Cacho

TI__Mastermind 39855 points

Hi Jared,

The DC resistance is 48Ohms +/- 25%. The default is fast mode ('0' in the bit). Please note that the resistance does not change between modes. Slow mode changes the slew of the IO while keeping the impedances the same.

Sincerely,

Gerome

Jared Becker over 3 years ago in reply to Gerome Cacho

TI__Genius 11845 points

Hi Gerome,

So even though the bits are called "mac_t/rx_impedance _ctrl", they don't actually control impedance?

-Jared

Gerome Cacho over 3 years ago in reply to Jared Becker

TI__Mastermind 39855 points

Hi Jared,

That is correct.

Sincerely,

Gerome

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DP83TC814R-Q1: MAC Impedance Control