Should have done a quick search as it was a basic question:
Can you give me more details on how v2.3 DC works internally?
Below is a block diagram of the v2.3 DC circuit. All relevant parts are marked in red. The mcu controls two high-side switches (HS switches): it turns on switch 1 to engage the boost converter (based on MC34063), which generates 22V DC and stores that into a capacitor; it then turns off switch 1 but turns on switch 2 to dump the boosted voltage to the common (COM) wire, which provides the in-rush current. Finally it turns off switch 2 and the input 9V DC continues to provide the holding current through the diode.