I'm working on a project that requires the following voltages and currents:
- 3.8V at 2A
- 3.3V at 900mA
- 1.8V at 100mA
The input power to the system is a 12V wall wart adapter.
I've decided I'll run the 1.8V from an LDO on the 3.3V supply as it'll keep cost lower than supplying its own SMPS.
Now the question is, should I supply the 3.8V and 3.3V side with 12V OR should I supply the 3.8V with 12V and then feed the 3.3V with the 3.8V whilst upping the current supply for the 3.8 to accommodate for the extra power required.
I'm thinking it'd be most efficient to daisy chain the 3.3V to the 3.8V as it'd lower the switching frequency and thus the switching losses.
Do I have my thinking right, are there any other design concerns I'm missing?