Sizing the boost for a 5.1 V rail
The TPS61235PRWLR is a fixed-output boost converter from Texas Instruments that delivers 5.1 V from an input range of 2.3 V to 4.5 V. The internal switch handles up to 6.5 A, so the output current capability depends on the input-to-output voltage ratio — at 3.3 V in, you can pull roughly 3.5 A continuous before hitting the switch current limit.
The part comes in a 9-VQFN-HR package measuring 2.5 mm x 2.5 mm. Without adequate copper area, the switch current derates faster than the 6.5 A peak suggests.