Quoting ivp <joecolquitt@clear.net.nz>:

> Having my first proper play this evening with a battery booster,
> the ST L6920
>
> I ordered some 10uH inductors from Farnell. The 1077049 to be
> exact, the Murata 22R103C. It's a 6mm x 8mm cylinder, through-
> hole
>
> With 3.8V in / 5V out, the circuit is drawing around 15uA without
> a load from Vout to V
>
> 4k7 (1.07mA load) draws 1.51mA from the battery
> LED + 680R (4.87mA load) draws 6.69mA
> 1k (5mA load) draws 6.96mA
> LED + 1k (9.87mA load) draws 13.65mA
>
> Efficiency is a pretty consistent 72%. I expected > 90%

Take the 5mA case. Input power is 3.8V * 6.96mA = 26.4mw
                    Output power is 5V * 5mA = 25mW

Efficiency = output power/input power  = 94.7%



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