I am using a TPS63000 in the following circuit - attempting to make a buck/boost converter to take a single cell lipo in and set for 3.0v on the output.
However, the output voltage is widely variable depending on the input voltage - it tracks about ~1v below the input.
2.8v in -> 1.9v out (FB pin @ .3v)
3.0v in -> 2.1v out (FB pin @ .33v)
3.5v in -> 2.6v out
4.0v in -> 3.0v out (FB pin @ 0.5v)
4.5v in -> 3.6v out
I have tried:
-Building two different boards (one hand assembled with hot air, one reflowed in an oven)
-Different ICs (also tried using the TPS63000-Q1)
-Tying VINA/EN/PS_SYNC to VIN (removing R11 and C8)
-Different inductor (NR3015T4R7M - 4.7UH 1.04A 144 MOHM)
Any thoughts on why this is happening?