Hi, I'm designing a WLC system based on BQ51003 receiver and BQ500412 TX, with custom, small geometry coils.The target max load current on the rx side is some 200 mA and, ideally, the TX side could be powered directly from a 5V USB device port.
I'm looking at the BQ500412 EVM schematic, but there a 5V to 12V DC-DC converter is used to supply the coil power drivers with 12V. My question is, would it work just as well with plain 5V VBUS as the swtiched power rail through the coils? As stated, the coils are customized and strict Qi compliance will probably not be possible anyway.
Differences to the EVM schematics, related to the coil power path, include using a TI CSD95379q3m on the high side and dual CSD16301q2 on the low sides (only two coils will be used, for separate and mutually exclusive charging positions). I've adjusted the voltage dividers in the COMM+ paths, before the analog mux:es (100k / 10k vs. 200k / 10k in the EVM schematics). Is this correct and/or are there any other modifications needed for 5V switched coil voltage?
Other changes include using digital MCU GPIO instead of stand-alone sleep/snooze/snooze-cap etc mechanisms, but I already found a lot of helpful comments regarding that in another thread here (thanks!).
Thank you.
/Mathias