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Photovoltaic MOSFET Drivers - Voltage Rating

ElecDesigner

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Hi,

I am looking at various Photovoltaic MOSFET Drivers for a high voltage application. Looking for something that will ideally withstand about 4/5KV DC continuous during normal operation. Various devices are specified for this but when looking onto the details, they do not mention the continuous withstand voltage in the specs but in the safety specs 5300V (t =1min) is stated. I'm a little confused about if these devices can handle the the large DC in to out difference continuously or just as a safety spec (e.g. for mains isolation).


See this one as an example....
 

FvM

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The datasheet has a peak working voltage specification VIORM of 890 V according opto-coupler safety standard IEC 60747-5-5. A pessimistic assumption would be that the internal isolation barrier isn't designed to keep higher continuous voltages, apart from possible requirements for transient voltage withstanding and external clearance/creepance distances.

Apart from this specification, you would need to mold your circuit to achieve 4 or 5 kV working voltage with only 7 mm package creepage distance.
 

mtwieg

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It's normal for a device to describe its insulation according to standards, for example UL1577 and DIN EN 60747-5-5 in this case. Often they describe max voltage for short times, like 60s or 1s. Sometimes they describe the "working voltage," which refers to continuous operation. Depending on your device and your country, you may be required to use parts certified to specific standards.

I have never seen any PVI with a working voltage >1kV (at least not in a monolithic package like this). Not even sure if any certifications extend to such voltages.
 
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I have never seen any PVI with a working voltage >1kV (at least not in a monolithic package like this). Not even sure if any certifications extend to such voltages.
I've seen one device with 1250V working voltage (IORM), still with small creepage distance of 7 or 8 mm. There are no photovoltaic couplers in wide packages availiable. The problem is as I think that photovoltaic drivers need high optic efficiency which is hard to achieve with large isolation gap.
 

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mtwieg

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On a similar note, I assume that these standard optos (see link below) can be used for continuous 4/5KV working.
Doesn't looks anything wrong to me and 15KV is mentioned but asking the question anyhow.

What I need to see when determining continuous working voltage is either:
1) Certification which refers to continuous/working voltage
2) A clear statement by the manufacturer stating that continuous operation at a given voltage won't degrade component lifetime unacceptably. For example, I've seen in some analog devices datasheets that they spec working voltages which result in failure rates <0.1% over 20 years.

That datasheet gives neither. The only certification it mentions is "UL recognition is for 3500 VAC for one minute." That doesn't mean it can't work at 4-5kV continuously, but I certainly wouldn't bet on it.

They don't explain what their 15kV isolation rating is based on. It's apparently not some standard, so I wouldn't trust it without more info from the manufacturer.
 

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