Consider the CBTD16210/1 instead of the LVCH162245

[nonarkitten]

In this use case, they're functionally similar, but the CBTD:

• has no direction (save drd_rl_to_fpga)
• has a much shorter propagation delay (150ps versus ~2.5ns)
• has slightly more IO per 48 TSSOP (20 channels versus 16)
• use virtually no power themselves (current is drawn thru the CBTD, not from it)
• if space permits, two CBT16211's could replace the three LVCH162245's

The CBT's are more common and cheaper than the CBTD's. TI makes a specific 5V to 4.3V LDO for this (since the CBT's clip another 1V off that for 3.3V output): TLV70243DSER.

You would then be able to omit the 3.3V LDO by taking the 4.3V power meant for the CBTs to some of the spare pins and using the other side pins as a 3.3V power source. Then you're just swapping the existing 3.3V LDO for the 4.3V LDO.