At 01:50 AM 2/26/02 +1100, you wrote:

>And BTW, that's continuous current.

Absolute maximum clamp current is +/-20mA. Absolute maximum.

>For narrow pulses, the PIC could handle proportionally more current.

Unh, no, not a good assumption.

>My point is that the resistor will die long before the PIC !
>(a 1 Meg resistor with 20 KV across it is dissipating 400 Watts !!)

More likely it is arcing and dissipating 40kW ;-)

>And of course you would have a small cap at the PIC to filter out the HF
>junk.
>This cap would  also greatly limit any spikes.

Really? Without doing the math, I'd certainly think that any such
capacitor would cause a lot of phase shift before it did much good.

Best regards,

Spehro Pefhany --"it's the network..."            "The Journey is the reward"
speff@interlog.com             Info for manufacturers: http://www.trexon.com
Embedded software/hardware/analog  Info for designers:  http://www.speff.com
9/11 United we Stand

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