High voltage feedback measurement

[Akwasi]

I have a converter with 1kV output voltage which charges a 47nF capacitor,
to measure that voltage I'm looking for a solution as an alternative to a fixed resistor divider to let the capacitor store the charge as long as possible, >1sec,
I thought about taking sample measurements at intervals, for example to use a MOSFET to switch the resistor divider off between the measurements,
but all the MOSFETs I see are specified below 1kV,
maybe an option would be to put some z-diodes in series with the MOSFET, but does this really make sense ?
I assume that even with the Z-diodes in series the MOSFET will still see the 1kV in off-state,


any ideas ?
Thx, Andreas

 

[chuckey]

So T > 1, So CR> 1, C = 50 X 10^-9, so if R = 1/50 G ohm, or 20 M ohms, Easy, go out and buy a 500 M resistor, this will give you an intrinsic time constant 10X greater then what you are after.
Frank

 

[Akwasi]

agreed, the 500M resistor is a valid solution, in series with a 1M the 1kV would result in 2V, but I'm still looking for something that does not constantly drain current from the capacitor