The MIC2251-2YD5-TR: The 900 mA switch current limit and 2.5 MHz switching frequency let it generate output up to 37 V from a 2.5 V input.
900 mA switch — sizing the output power
The 900 mA switch current is the internal MOSFET's peak limit, not the continuous output current. For a 37 V output from 2.5 V input, the maximum output current is limited by the switch current and efficiency.
2.5 MHz switching — inductor and capacitor selection
The part is not synchronously rectified, so the Schottky diode's forward voltage adds to the loss budget.
No pin-compatible second source or official successor is listed, so single-source risk applies for production builds.