2KV High-side, low-current measurement

Question

Is it possible to use an AD620 connected to an AD210 to measure high-side current through a sampling resistor? With the REF line on the AD620 and the Icom line on the AD210 connected to the bottom of the resistor (and the top of the resistor is connected to 2KV). The REF/Icom voltage measured with respect to ground would be very close to 2KV. 
 If I were to do that what ground referenced voltage would I measure at +VISS on the AD210? Would it be 2KV - Rsense*Iload + 15V? That is, assuming I didn't let the smoke out. ;-) 
 Are there any common mode limits I need to be careful to watch out for?

ADIApproved · Accepted Answer

The 600V DC working voltage is very conservative, but there's another factor to consider (which I did not in my initial response): creepage. Using the IEC 60664-1 insulation coordination standard, a 2 kV DC working voltage requires 14 mm creepage. This is assuming basic insulation with the equipment operating in a pollution degree 2 environment. 
 
 You can run two isolators in series to effectively cut the working voltage in half for each component. This reduces the creepage requirement to 7.1 mm, which any of our 16-SOIC packages will meet. The ADuM6000 could support 1kV DC working voltage. ADI has published an app note with an example of this approach. The inefficiency of the ADuM6000 is more of an issue. You would need to place a 2-channel isolator in series with the AD7401A, such as the ADuM2281 . 
 
 Sorry I didn't think of this sooner. 
 
 DaveC)

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2KV High-side, low-current measurement