TX2 Ethernet PHY BCM54610 Broadcom

Hi all,

The TX2 uses the Broadcom BCM54610 GbE Ethernet Phy. On p36 of the TX2 OWM product guide, it discusses a maximum length constraint of 109mm (690ps).

Our custom carrier board has a trace length of 157mm with little chance of being able to make this shorter due to mechanical constraints.

I am looking for:
A) The datasheet of the Broadcom BCM54610 (not available on their website) to check this 109mm spec,
B) Any advice on if this constraint can be broken and what we risk if we do (signal integrity I’m sure but other ICs are perfectly able to use differential traces for longer lengths), and
C) Any suggestions as to suitable full bi-directional buffers.

We specified a buffer, however, this is uni-directional which would likely break the cross over auto-negotiation.

Many thanks,
ED

Hi, the constraint should be follow before design start. Performance will not be guaranteed if it is broken. No such buffer experience can be shared. Suggest to try to eliminate the gap by optimize the design.

Thank you for your comment.

As mentioned, we have some mechanical and physical constraints that prevent simply eliminating the gap. A buffer would be a useful suggestion as I’m sure others would appreciate it. With the datasheet, it would be easier to tell why this constraint is present and if we can make a trade-off elsewhere that would satisfy overall performance.

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The datasheet of the Broadcom BCM54610?