How can I calculate what the current "I" output can i have for determining my Efficiency.
I am building a simple linear regulator and is it possible to know during design of the circuit , what the efficiency of the circuit would be?
Should I just assume input current to be the maximum current it can out put, or should I put in a resistor for my calculations and see how much current it will draw, if its the second one, then how do I determine the impedance due to other parts in my circuit?
Best Answer
The efficiency is:
$$\eta = \dfrac{p_{out}}{p_{in}} = \dfrac{V_{out}\cdot I_{out}}{V_{in}\cdot I_{in}}$$
For a linear regulator, assuming the output current is much greater than the regulator circuit's internal currents, we have \$I_{out} \approx I_{in}\$ thus:
$$\eta \approx \dfrac{V_{out}}{V_{in}}$$