Electronics > Electronics

Current Draw of A Voltage Regulator

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airman00:
Hello,

Lets say a voltage regulator provides 5V @500mA output . Does that mean that the regulator is always drawing 500mA from the power source or is the current draw of the regulator dependent of the circuit draw on the output of the regulator?

So for example if I were to connect a 25 mA draw to the regulator, would the regulator be drawing the full 500mA from the source or would it be drawing only the 25mA ?

Trumpkin:
I think the regulator can draw up to 500ma but I don't think it would draw 500ma all the time.

izua:
No, it will always draw more. It depends on the input voltage, too. Talking, of course, about the regular type (with a voltage reference and an unsaturated junction acting as a power output)
There are also the low dropout and the switchmode regulators, which reach way higher efficiencies.

airman00:
so it would draw the full 500mA all the time?

izua:
in my experience, linear voltage regulators sink a bit more on the input then the current sourced on their output.
so, if you will draw 500mA all the time from a LVR's output, it will draw at least 500mA on its input.

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