Looking for opamps with ability to tolerate input voltage above V+ ?

I have a board which is currently using several LT1491's, specifically for their ability to tolerate up to 44 volts above V+ at the inputs. The down side, is that they are expensive, and frequently out of stock. I'm curious is anyone out there is familiar with a similar device which might be a bit cheaper. I'm using this on heavy equipment with a 24v system. Commonly the LT1491 has a V+ of 5v, however the inputs could momentarily be as high as

28v (due to miswires in electrical assembly).

Any ideas?

Thanks,

Chris

Reply to
Christopher Ott
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(setting a Fup2 s.e.c)

Christopher Ott schrieb:

If the high input voltages are only due to miswires, you might as well add protection circuitry to a more common, standard OP.

When looking for OPs that accept voltages significantly above V+, they all are rather esoteric, expensive and/or hard to get. The good ol' TL072, however, at least accepts input voltages /up to/ V+, which might be sufficient in some cases.

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Dipl.-Ing. Tilmann Reh
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Reply to
Tilmann Reh

Zener diodes??

Reply to
Richard

Current limiting resistors and schottky diodes to the positive supply?

Reply to
William P.N. Smith

Add a clamping diode from the input to the positive supply rail of the op amp, and add a small resistor on the input signal to keep it from frying the diode (assuming there isn't already one there for the circuitry)

That sort of problem could be designed out.

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default

the way I'm reading that, they just need to survive, they don't need to function correctly in those conditions - right???

two:

build your own op-amps from discrete transistors. pass labs have an article on their web site.

use series resistors (eg 1K) and shunt diodes to VCC or to a 3.9V zener,

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   Jasen
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Reply to
Jasen Betts

and might eliminate need for a fancy ESD protection device as well.

Reply to
CWatters

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