The new PGA2500's ADC and DAC meed plenty of clean +5v power !

If I use the same +5v rail to power the DSP and ARM MC with some head room I think 4A would be safe

I don't think I'll ever use more than 1amp neg 5v so that negative rail can stay the same with the TPS regulator.

I'll have a 3.3v 2A LDO on the main board to power the digital stuff ( DSP and ARM )

Amazingly the board got a lot smaller even though it can make 4A +5v from 7v - 25v or possibly higher.

this was mainly down to the 4A capable TPS low noise regulator and the LMZ23605. Its not cheap! I'd love to know

if anyone has a better Idea ? the LMZ23605 has an integrated inductor and so reduces footprint of the design although

it is itself quite large ! 

anyway , here is a pic of the layout , I think i will make this anyway to power my next main board.

I'm not really convinced I should be running the 3.3v LDO for the digital stuff ( DSP and ARM ) off the analogue +5v rail !

perhaps that could add noise to the analouge +5v rail on the preAmps ? anyone have any thoughts on that ?

Will the LDO put noise onto its input ? can I isolate this without transformers? or should I really have a whole other

channel to make the digital power?