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TPS54531: Suitability for 12V plane

Part Number: TPS54531
Other Parts Discussed in Thread: TPS51120, , LM5176

Good evening,

My 4-layer PCB has 3V3, 5V and 12V rails, which will be organised as various polygons on the PWR plane (layer 3). The input source for the board is 7-27VDC, which goes through an EMI filter stage before a TPS51120 dual step-down controller to produce the 3V3 and 5V rails. I'm thinking that the 12V rail can either be regulated from the 7-27VDC input directly, or boosted from either of the 3V3/5V sources. First question (coming from a novice), would a buck-boost topology or a boost (from 3V3 or 5V) topology be recommended/advisable to generate the 12V rail? The 12V rail will be used for the following:

  1. Power for a precision voltage reference IC
  2. Power for display backlight LEDs
  3. General purpose 12V outlet power

I expect the 12V rail will draw upwards of 5 amps (maximum). If the buck-boost topology is a recommended/advisable approach, would the TPS54531 be a suitable IC?

Thanks!