Linear Voltage Regulator help

Thread Starter


Joined Sep 24, 2018
Hi, can anyone help me get the efficiency or any other values. This is the first time I encountered this type of linear voltage regulator so im not sure what to do.

: cleaned up your image.

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Joined Mar 14, 2008
You question is way too general.
Have you looked at the data sheets for those regulators to try to understand what they do?


Joined Feb 8, 2018
Ignoring the losses due to powering a linear regulator's own circuity, the efficiency is simply Vout/Vin. For example, if the input voltage of a regulator is 9 V and the output is 5 V, the efficiency is 5/9 or 56%. You don't have to consider the current because the output current is equal to the input current, but ...

In reality, in some cases the power used by the regulator itself must be considered. If the output current is very low, the few milliamps used in the reg's circuit may be significant. With many regulators, the power they consume is more or less independent of output current. Some reg's (old low dropout voltage designs) are less efficient because some moderate fraction of input current goes to ground instead of to the output. With these reg's the power they consume is partly fixed but mostly proportional to output current.