IMP003: What does the circuit connected to DCDC_IN and DCDC_OUT do?

Why is there a coil (L1) and capacitor (C11)? Is this circuit required? I couldn’t find that info in IMP003 datasheet. What is the voltage? Can I power it externally?

This is the DCDC buck for the wifi chip’s digital core, and input to some of its internal regulators. You can’t power this externally, as it’s under firmware control.