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Suggest POE PD based power supplies for high precision ADC

Other Parts Discussed in Thread: ADS1261, PGA280, LM20123, SN6505B, ADS125H02, TPS7A39, TPS23730, TPS23731, PMP6672

Hello,

I'm interested in whether TI has a suggestion for some power supplies for a high-precision data acquisition device that will operate from POE Power.

Low noise is the biggest factor, size is mostly unimportant and cost is not relevant.

AUX Power input is required - this design may have to operate from adapter power rather than POE so a wide input range of ~18V to 55V is necessary.

We'll be using a 24 bit bi-polar ADC (probably ADS1261, but not decided yet) and a PGA280 device.

Requirements are for the POE PD to be fully isolated.  Power rails required are:

+5V or +12V - Can be noisy, only used for non-critical devices.  (Really anything above 5V is acceptable)
+3.3V - ADC and Microcontroller power.  Power budget around 350mA
+2.5V - ADC AVDD
-2.5V - ADC AVSS
+18V - PGA280 AVDD
-18V - PGA280 AVSS

My initial thought is to use a POE PD design that outputs 5V.
Create 3.3V using a LM20123 from the 5V
Create the +/-18V using a SN6505B+TPS7A39 from the 5V (As per the design in the ADS125H02 Datasheet)
Create the +/-2.5V using a SN6505B+TPS7A39 from the 5V (Similar to above, but with a lower output from the SN6505B)

Does TI have any thoughts on this power distribution scheme?  I'd also be interested in TI's suggestions for the POE PD Reference design the with the highest power quality.

Thank you