U3
RT6150
IC
Buck-boost regulator
About this component
Generates the board's fixed 3.3 V supply for the RP2040, flash and the 3V3 pin from VSYS, whether the input is above or below 3.3 V (for example a single Li-ion cell or two AA cells). GPIO23 drives its power-save pin: low (default) lets it use PFM for low light-load current, high forces PWM for lower ripple. If 3V3 is missing while VSYS is present, check the 3V3_EN pin (pulled to ground stops the regulator) before suspecting the chip.
What it does on this board
Generates a stable 3.3V from USB/VSYS.
Pinout & readings
No pinout or reference readings yet — these show what each pin does and what a healthy part should measure.