Power conversion efficiency and power supply efficiency indicate the ratio of output power to input power.
Efficiency [%] = (output power / input power) x 100
Loss = output power - input power
If the efficiency is high, the power to obtain the output power can be reduced and the conversion loss also becomes small. That is to say, if the efficiency is high, the power consumption is low, loss is low, and amount of heat generation is small.
When calculating a single power supply efficiency of DC/DC converter or voltage regulator, etc., following calculation is available.
Efficiency [%] = (output power / input power) x 100
= (output voltage x output current) / (input voltage x input current) x 100
How to measure the efficiency
The efficiency under each condition can be obtained by correctly measuring output voltage, output current, input voltage, and input current using stabilized power supply, multimeter, electronic load / resistance load, etc.
To measure the current, it is necessary to insert a multimeter into input / output line. As multimeter causes voltage drop, correct measurement of input voltage / output voltage near IC is required for correct calculation of efficiency.
In addition, using voltage setting value of stabilized power supply or output voltage setting value of DC/DC converter / voltage regulator for calculation of efficiency causes wrong calculation of efficiency.