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Isolated high voltage side measurement problem (short kills IC)

Question asked by FernandoMierHicks on Apr 1, 2013
Latest reply on Apr 1, 2013 by MSCantrell

Hi:

 

I am testing a circuit that measures the voltage generated by a high voltage converter.

 

An off the shelf converter (EMCO) generates 1500 volts that are delivered to a load. A voltage divider divides this voltage by 10,000 and an isolation amplifier (AMC1100) is used to transfer the value to a microprocessor on the low side. An isolated dc-dc converter (ADUM6401) is used to power the amplifier on the isolated side.

 

Schematic

https://docs.google.com/file/d/0B8t-JKa-x1NXSDd1V19DUHllQ1k/edit?usp=sharing

 

The circuit functions very well until a short on the load happens on the high voltage side. When this happens the Dc-Dc Converter/ isolation amplifier start consuming much more current, after several shorts on the high voltage load these devices stop working altogether.

 

My power supply system has to be robust enough to handle shorts on the high voltage load. 

 

When a short happens on the load, could there be voltage spikes induced on my dc-dc converter or amplifier and killing them? I have tried putting voltage suppressor (suppressing 10 volts) both on the input and power supply pins of my amplifier with no good results.

 

Again the circuit works fine as long as no short happen on the load.

 

 

Thanks.

 

 

Fernando

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