Convert 20~70 Volts DC to 15v 3A

My input is about 20 till 70 DC volts.I need to 15v about 3A in output.
What is the best way to do that.
Very thanks.

Most big linear regulators only have a 35V input output differential.

Switching ones like the LM2576 HV can accept up to 60v input.

Perhaps if you search you might find something that can do 70V ?

What are you using as a power source that has such a wide variance ?

You need a suitable buck convertor - I'm sure they exist with that range.

Designing one yourself is a significant project in itself....



Costly, but meets your requirements: RCQ5072S15

Costly, but meets your requirements: RCQ5072S15

Seems its minimum input is 43v, he want 20v - 70v, impossible dream ?

Missed that. Might be possible but 20V in is really close to 15V out.

One also must consider that when your input voltage is 70V the differential voltage to your output will be 55V. Now this will be a net power dissipation of 55V x 3A = 165 Watts. This is assuming you are drawing 3 Amps but even at 2 Amps that's 110 Watts requiring a lot of heat sinking in a Linear Regulator.

If you go to a Switch Mode/Buck Power Supply the heat dissipation will be far less but most of these don't run in that voltage range. Also if your input voltage is fluctuating from 20 to 70V fairly quick you may have line regulation problems on the PS Output.


Doing it linear is nearly impossible. Switching is doable but it's a weird voltage range so not many chips are made for that.

But really, it's a XY-problem. What on earth is giving you that broad voltage range? And what takes 3A at 15V?

@leoncorleone very rudely started a new (more specific) thread and failed to follow-up here.

Thread locked.