Re: micro power square wave oscillator


"D from BC"

I was thinking of loading too..
Mmmmm....
1/100Khz = 10uS

Let's say a risetime and falltime of 1uS.
Say supply = 5V

By
I = C dv/dt
And assuming a 100% efficient circuit..

10uA = C 5V/1uS

C = 2pF !!

With those assumptions and if I did the math right, it suggests you
can't even drive a typical scope probe without going over the supply
current spec.


** Nonsense.

The load charging current only flows during the rise-time of the square
ave - which even in your hand-picked example is only some 10% of the time.

The average supply current is therefore ( for your example) only 1 uA.

Similar math applies for faster rise times making the AVERAGE current draw
essentially independent of the rise-time for fixed frequency and load C.


...... Phil




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