HV Snubber circuit

  • Thread starter Jdo300
  • Start date
  • #1
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Hello All,

I'm designing a high voltage snubber circuit to protect a MOSFET which is driving an inductive load to produce BEMF spikes. I am expecting that the snubber capacitor will have to handle 500-1000V transients with greater than 10000V/ms rise and fall times, which I hear can burn up most caps. So I began looking for some good RF capacitors (around 5-10 nF) that could handle the load and someone recommended to me that I look at using Silver Mica capacitors. But seeing how expensive they are, I am wondering if there are any alternative types of capacitors that have similar specs. I would just go for ceramic caps, but I hear they are not good for this either?

Thanks,
Jason O
 

Answers and Replies

  • #2
NoTime
Science Advisor
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You hear right about most capacitor types failing in this type of installation.
I think the ones we used were Polypropylene film or Polystyrene film capacitors.
 
  • #3
Can you catch most of the BEMF using a flyback diode across the load?
Otherwise you want to look at polypropylene film construction.
What is the total capacitance you require?
The 10kV/ms rise time is generally easy to meet, as most snubber capacitors are rated at >1000V/us at that voltage.
 

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