I have an electrical control box that needs 48v, 12v, and 5v to power stepper motors, sensors, and microcontrollers, respecitvely. All power items will be mounted on a DIN rail right next to each other. Is it better to have an AC-DC power supply for each output voltage, or one larger 48v supply and use DC-DC converters to get the lower voltages needed? It's cheaper to get seperate power supplies, so if there aren't going to be any negative effects I'd like to go that route. Thanks!
Both works, however, the separate AC/DC supply is a bit better.
- AC/DC power supplies are dirt cheap.
- There are plenty of AC/DC that can be rail mounted, DC/DC is more difficult to find.
- You will have overall fewer conversion losses.
Where it is debatable is the 12V -> 5V where you can have a 2$ small converter onboard if you want to save some space, assuming 5V requires low current.
You need to connect all the negative to a common line.
Parallel is better because it improves the reliability. For your logic, you want that independent so you can continue to monitor systems like motor position and fluid levels even if you have a major failure that causes one of the other supplies to completely fail. This also allows you to have some sort of logic level fault detection for the other circuits that can help with troubleshooting during failures.