I'm developing a PCB for a LiON battery powered portable device featuring the Raspberry Pi CM3+ compute module, but am having difficulty verifying my power budget for the system due to the datasheet and schematic omitting the specifics of the regulator circuit for the switching power supply on the module. I need to determine the requirements for the system voltage rails, to ensure I have adequate current capacity on the 3.3V rail used to power the Pi and display circuitry.
VBAT is listed as accepting an input voltage of 2.5-5.0V, and implicit to the name VBAT indicates it can accept a variable input voltage and buck/boost as necessary, but all the schematics I find online feed VBAT a 5V input rather than a direct battery voltage. Do I need to generate a separate 5V boosted rail on my own, or can anyone directly confirm that the CM3+ can operate within the lower voltage range listed in the datasheet? Does anyone know what regulator is used for the SMPS circuit on the CM3+ so I can look up a datasheet, or have full schematics? Why are those sheets omitted from the CM3+ schematics in the first place, contractual agreement nonsense?