Electronic – Power management for a 5V 12A load

currentheatsinkpowerpower supplyvoltage-regulator

I need to deal with a peak load at 5VDC and about 11.25A but I'm not sure how to manage this.

I have 5 individual loads of 2.25A and small loads from an MCU and some LEDs all of which should fit into the 12A. Another requirement that I have is that power supply can be placed in a sealed enclosure so that it can be placed outside and not have water get in. I suppose an aluminum case might help with this.

I am not quite confident enough to build my own power supply. Dealing with mains is a bit scary. I've found some a RC car battery charger power supplies that will supply 14VDC @ 16A (Turnigy T-20Pro). They have fans in them which wouldn't do much being in a sealed enclosure. My though was that I could use simple 5V linear regulators for each of the 2.25A loads and another for the MCU and LEDs.

What alternatives do I have and/or what trouble am I going to run into?

UPDATE:
I wasn't explicit about the power source, sorry. It will be 120v 60Hz AC.

UPDATEv2:
Most of the load (5×2.25A=11.25A) will be outside the enclosure as the project is a LED Christmas light controller.

Best Answer

If you're not comfortable working with mains voltage, and assuming that your loads are in the same enclosure as your power supply (i.e. you're generating a lot of heat in an enclosure), you might consider a AC->DC power supply mounted remotely from your enclosure, and running 5V into your enclosure.

Normally, voltage droop would be a concern under such use cases, as it only takes 0.04 ohm of line resistance to drop 10% of your supply voltage. Many power supplies have remote sense leads, such that the power supply closes its control loop around the supply voltage at your enclosure, compensating for any transmission losses.

The benefits of this approach include reduced power dissipation in your outdoor enclosure and only hand-friendly 5V in the enclosure (but watch out for shorts!). The downsides are the need for a separate (hopefully indoor-rated) enclosure for the supply and possibly a slightly higher cost for a AC-DC supply with remote sense capability.

Related Topic