any experts here on upc1237 ?

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cakyol

Member
Joined 2014
#1
Can the upc1237 be driven by 50V AC (Vac) & 70V DC (Vcc)?

According to the datasheet formulas, for the above voltages, Rac should be 32k ohms and Rvcc should be 19k ohms.

I intend to drive Rod Elliott's Mosfet relays (2 in series) from pin 6 so only about 15 ma will be needed from pin 6.

Are there any other components I should be careful about ?

Has anyone actually ever used those hi voltage values ?

I already have this available on the power supply and did not want to get another transformer.

Thanks
 
#6
The type that is readily available from Chinese sources is µPC1237HA. There seems to be more than one manufacturer but apparently most are now good copies and they've been widely used in local commercial and DIY applications for more than 10 years, to my knowledge. It comes in at least two different 8 pin SIP outline packages and markings so checking authenticity won't be easy.

The problem is to ensure your fakes are better than other fakes/copies 😀 which may not work as well or reliably in your application. That means testing the function for its threshold fault current before assuming it will work correctly. Don't assume that all is fine just because the relay drops out when you short the output or the label on the IC and your schematic look OK.

Here's one genuine source, if interested - http://www.unisonic.com.tw/datasheet/UPC1237.pdf
 
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#10
The only reason I am using the upc1237 based circuit over a discrete one (Rod Elliotts' for example) is the unfortunate fact that the discrete circuits I know of do not 'latch' on a fault condition, which I very much prefer.

If anyone knows a reliable, fast circuit which also latches and is not too complex (some are very complex for reliability), and I can find PCBs for it, I would gladly use it.

Thanks
 
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