Voltage regulation circuit 12V to 5V in 5A range

[tumbleweed]

I just noticed the LM1084-ADJ is claimed to "provide 5 A at high efficiencies and very low drop-out." I just ordered a few from Digikey.

The only difference between the LM1084-ADJ and the fixed output LM1084-5 is the latter already has the resistors to set the output voltage built inside it. You will only get 5A out of it if you have the input > the Vdo drop out voltage spec, and stay within the max power dissipation. With no heatsink you're not going to get anywhere near 5A out, not with 12V in.

You said the output voltage of the LM1084-5 dropped when you added a load. That shouldn't happen as long as you're within the datasheet specs.

If you're trying to get 2.5A out, with your 12V adapter that gives a Pd = (12v-5v) x 2.5 = 17.5W !!

Yeah, I'm waiting for a 9V 2A wall adapter to help reduce the waste heat. I'm getting 7V 2A wall adapter tomorrow to reduce that even more.

You'll need an adapter with more than 2A out if you want 2.5 or 5A out of the linear regulator.

[Ioannis]

Not so tumbelweed.

With Linear regulators, your Input current is the same with the output current! Beware of that! Plus the current of the regulator of course, though this is small enough.

The opposite happens with SMPS. In that case wattage is the same plus the losses in the regulator itself.

The voltage drop with increased load is called Load Regulation and is there in the specs. And of course it is different for every regulator, either linear or SMPS. Besides that spec, which is typically small enough (less that 1% for the TPS565208), the voltage will drop for many other reasons, like design of PCB, part selection, thickness of wires and the point where output voltage sample is taken for the regulator to compensate for. the drop.

More output current, more copper on PCB and thicker wires are needed. After all, the regulator will have the nominal voltage on the output but if your wire is 10 meters long, you will have voltage drop on the cable, right?

I think TPS565208 is one of the easiest to handle and very good in terms of cost, pcb estate, output noise and efficiency.

Ioannis