Are there devices that are fet based and have optical isolation? e.g., maybe something that uses a transformer to isolate the gate? I remember seeing, I think from TI, some very small transformer isolation IC's and I imagine one could combine this with a fet to get some pretty responsive isolation like behavior(obviously in this cause it's not optics involved).
Otptofets
Feb 17, 2010
5 Replies
Analog Devices and TI both make logic isolators that are very fast. The ADI parts are inductively coupled, and the TIs are capacitive.
Some of the ADI parts include a power isolator too, which can be very handy.
John
"John Larkin" wrote in message news: snipped-for-privacy@4ax.com...
The ADI power isolators are good for 100ma.
Cheers
Jon Slaughter wrote: : Are there devices that are fet based and have optical : isolation? e.g., maybe something that uses a transformer : to isolate the gate?
You don't mean such devices as the Panasonic AQY221 or Toshiba TLP3250 ? There is a photodiode illuminated by the LED, and the photodiode current drives the gate of a MOSFET switch. Slow, but convenient relay substitutes.
Regards, Mikko
http://www.fairchildsemi.com/ds/H1%2FH11F1M.pdf
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I have used the H11F1 and H11F3 when it was first released by GE The fet resistance depends on the diode current, so it can be used as a modulated resistance.
JCD
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