Hello everybody. I'm designing a custom PCB fed by a typical 3.7 V nominal 4.2 V peak lipo battery, where minimal area and thus component count is a key factor. Aside from the nrf52 SOC (evaluating both nrf52810 and 32), the board main power requirements will come from at most 2 DC motors and 1 stepper motor (3-5 V range), driven from two drivers with a total current of no more than 300 mA, motors that may be started and stopped with relative frequency.
I want to ensure efficient and reliable radio communication, and so I've considered several power setups I'd like to discuss with you, to better know if they are valid or if I may be missing something else.
- Using a 3 V LDO just for SOC and logic, powering the motors directly from battery
- Pros: simple setup, with reasonable power dissipation and a stable output with little ripple for the nrf52 and drivers logic
- Cons: motors won't have a constant voltage input, LDO efficiency
- Using an integrated inductor 3 V step down buck converter for the entire system
- Pros: regulated voltage for both nrf52, logic and motors, high efficiency
- Cons: intrinsic regulator output ripple voltage, motor operation could induce noise in the nrf52 power rail or transient voltage drops?
- Using an nrf52833 and power everything directly from battery
- Pros: lowest part count, simplest setup
- Cons: motors and nrf52 won't have a regulated input, nrf52833 regulator may not be enough for the radio power demands (in terms of stability or efficiency), may need to power drivers logic from a regulated nrf52 pin, motor operation could induce noise or transient voltage drops in the nrf52 power rail?
I'm also planning on enabling the nrf52 DCDC converter, as I think is a good compromise between the extra inductor and efficiency.
Looking forward to hear your thoughts about this setups. Thank you.
