I'm looking for a bit of a sanity check here (I'm a hobbyist) --

I want to use a 12v regulator capable of outputting 600mA

It's required that it be able to provide enough current to power a 12V to 5V regulator outputting 1000mA.

12 / 5 = 2.4, so theoretically the 600mA @ 12V should be able to provide 1440mA @ 5V, right?

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    \$\begingroup\$ Practically it'll be more like 1200mA 5V but yes (assuming the 5V regulator is a buck convertor, not a 7805 or other linear regulator) \$\endgroup\$
    – user16324
    Commented Sep 10, 2020 at 16:17
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    \$\begingroup\$ With good switchers this might just work but it seems like a relatively bad idea - you don't seem to have left any power budget for a 12v load so why have the intermediate voltage at all?. What's the overall design and purpose of the system? Why can't you just create the lower voltage output directly? \$\endgroup\$ Commented Sep 10, 2020 at 16:20
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    \$\begingroup\$ Work on 90% transfer efficiency for each regulator and ask yourself if it still stacks-up. \$\endgroup\$
    – Andy aka
    Commented Sep 10, 2020 at 16:28
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    \$\begingroup\$ Careful, vehicle systems routinely experience 48v or more surges and spikes. \$\endgroup\$
    – rdtsc
    Commented Sep 10, 2020 at 16:36
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    \$\begingroup\$ This sounds like going about things the wrong way. Find a 5v switcher with a wider input range, one suitable for automotive use. If you need a tiny bit of current at a steady 12v, you may actually need a buck/boost to provide that from a car electrical system... possibly even a boost from your 5v. \$\endgroup\$ Commented Sep 10, 2020 at 16:36

1 Answer 1


Assuming you are talking about 12V Voltage regulator that can provide up to 600mA, answer to your question is YES.

But since you need 5V input for you system you need to good step down circuit after regulator.

Also this is repeat for question here Can I turn a 12V 5A (60W) supply into a 5V ~10A (50W)?


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