Hi,

The current drain of 1µA is the average drain of the circuit.

A capacitor over the oscillators supply terminals is needed in your case.

The formula for capacitance is:

C = As/V [Farad]

*Where:*

A = Ampere

s = seconds

V = voltage drop allowed

If we assume each pulse is eg. 1ms in the 500ms period, the current drain will be:

500ms/1ms*1µA = 500µA.

500µA in 1ms assuming an allowed voltage drop of 0.5V, will take a capacitor of:

0.0005 x 0.001 / 0.5 = 1µF

A tantalum capacitor will be best, since it has lower ESR than an electrolyte. You might need a bit higher value than calculated, as they have a large tolerance on the marked capacity.