Turning an SCR _off_

Tim Wescott · 2008-11-15T21:43:40+00:00

OK, someone mentioned using an SCR to solve my little problem (see the "Depletion Mode Power MOSFET" thread).I've got some vague notion that if you pull enough current out of an SCR's gate it'll turn off.Is this true, or am I all wet? Is this a trick that I can expect to play with any SCR, or is it something that only a special few SCR's can do?I could only get it by the eagle-eyed circuit reviewers at my client if I could show them that there is no way, no how, ever, that their high-current DC line could ever get shorted by some honking big SCR that they let me put in.(I like their review process -- boards that don't work at least well enough for basic testing almost never make it in to layout, and they probably get half their boards into production with no spins at all).TIA.-- Tim WescottWescott Design ServicesDo you need to implement control loops in software?"Applied Control Theory for Embedded Systems" gives you just what it says.See details at

Nov 15, 2008 21 Replies

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JosephKK 17 years ago

They are actually the device of choice for things like variable frequency drives (in the 20 to 500 horsepower range).

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Spehro Pefhany 17 years ago

Not many MOSFETs with this kind of spec:

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Though the typical 5V Vce(sat) will result in a kettle or two of power dissipation.

Best regards, Spehro Pefhany

"it\'s the network..." "The Journey is the reward" speff@interlog.com Info for manufacturers: http://www.trexon.com Embedded software/hardware/analog Info for designers: http://www.speff.com

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