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Forum Index : Electronics : "neat" way to measure 400V DC by a micro
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Haxby Guru  Joined: 07/07/2008 Location: AustraliaPosts: 418 |
Hi all, I'm working on a microprocessor based precharge circuit board. It will measure the voltage on the capacitors as they charge through the precharge resistor, and once charged, will short out the resistor. So far I have just had a 6 second time delay, and it's been working ok, but that's a temporary solution, because one day the precharge resistor may fail for whatever reason, the caps won't precharge, and the main relay will go "splat" when it turns on. I'm looking for a way to simply and safely measure a DC voltage of about 200 to 420v and feed the signal to an adc on the micro. Is there a magic purpose built IC that can do this? If not my thoughts are to use a voltage to frequency IC then optocoupler the output to my micro. Any other ideas? |
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| Warpspeed Guru Joined: 09/08/2007 Location: AustraliaPosts: 4406 |
Voltage to frequency and then optocoupler will work fine. I use that in my BMS for fully floating individual cell voltage measurement. Very stable and accurate and simple. Cheers, Tony. |
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| noneyabussiness Guru Joined: 31/07/2017 Location: AustraliaPosts: 506 |
You could always use a resistor ladder and a zenner... through a optocoupler... keep it simple I think it works !! |
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| Solar Mike Guru Joined: 08/02/2015 Location: New ZealandPosts: 1122 |
Or use a chip designed for exactly that purpose ACPL-C87A Mike |
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| Haxby Guru Joined: 07/07/2008 Location: AustraliaPosts: 418 |
I'll be lazy and go with Mike's chip. The less components the better.  Mike how do you find all these speciality chips? Does it just come with experience? Hundreds of hours of perusing? Or something else? |
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| Solar Mike Guru Joined: 08/02/2015 Location: New ZealandPosts: 1122 |
Dunno, have used that chip in past projects, 45 years experience in electronics design helps too. |
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| Haxby Guru Joined: 07/07/2008 Location: AustraliaPosts: 418 |
Wow quite a bit of price gouging going on with the chip shortage. I couldn't get those chips for less than $20 each. The cheaper $5 versions are out of stock till Jan 2022! |
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| Solar Mike Guru Joined: 08/02/2015 Location: New ZealandPosts: 1122 |
Mouser have them is stock < $10 Mouser |
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