I am designing a DCDC Buck regulator for 12V to 3.3V system power supply. My controller; bluetooth & some other peripherals have following nominal currents on 3.3V rail as per datasheets (Details given below).
There is a required parameter of Io(max) for DCDC regulator. How to calculate maximum required current for circuit?
CAN Transciever: Nom: 40mA Max: 70mA Bluetooth LE Chip (+5dbm Transmission): Nom: 21mA Max: 32mA Microcontroller(@ 16MHz): Nom: 10mA Max: 28mA GPS: Nom: 46mA Max: 100mA
I would like to know which value should be taken to calculate maximum load current on this rail? Is it nominal current or peak current?
We generally follow: Io(max) = I(nom)*1.5. Is it OK? Because calculating with Max current ratings in datasheet will generate very high & way off current value for regulator current calculations as number of peripherals on line increases.
E.g. Here in this case: Nom (Total) = 117mA & Max(Total: 230mA)
**It is also observed that system current never reach to Max (total) current with full load on system.
Hence I would like to know which current value from datasheet should be generally considered for power supply rail current calculation & How to calculate Maximum rail current based on it?