Multiple regulators in the same circuit

[permal]

Hi,

I don't have a practical use case for this, but I'm curious - is it possible to have multiple regulators, such as two LM1085IS-3.3, in the same circuit to power different parts of the circuit or would they somehow interfere with eachother? If it is possible, what is needed to make it work?

[IanMacdonald]

Yes, this is quite standard practice for low currents.

Less practical for higher currents though, since the unnecessarily high input voltage on the lower voltage regulators will mean a lot of waste heat.

[Benta]

This is normal practice. It's called "point of load" or POL regulators.

[Zero999]

As mentioned above, that's common practise. The only thing to be wary of, is connecting the regulator outputs together can cause problems with stability, such as oscillation. Of course the 0V connections needs to be connected together, as with any non-isolated circuits, which need to interface with one another.

[permal]

Love the quick responses

So a circuit like in this image would be OK, as long as the two rails are not directly connected?

[KuroZ]

So a circuit like in this image would be OK, as long as the two rails are not directly connected?

Yes, there should be no problem with this. Just avoid powering the same device from more than one rail.

[permal]

Thanks to you all

[Zero999]

So a circuit like in this image would be OK, as long as the two rails are not directly connected?

Yes, there should be no problem with this. Just avoid powering the same device from more than one rail.

Yes, the two 3.3V rails should  be treated as different power supplies. If an IC has more than one VDD pin, they should all be connected to the same 3.3V rail. It doesn't matter which one, as long as the VDD pins on each device, all go to the same regulator.

[Ice-Tea]

Love the quick responses

So a circuit like in this image would be OK, as long as the two rails are not directly connected?

You may want to add some capacitors on the 12V line, though. Preferably local to each LDO