Use tl071 instead of ca3140?

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neazoi

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TL071 incorporates a 200 Ohm resistance in series with it's output pin which limits the current it can sink/source and gives it infinite short circuit protection. It should be able to sink around 40mA in short circuit conditions though. The CA3140 does not have a series resistor, it uses current limiting circuits instead. Otherwise they are both similar "first generation" BiCMOS op amps.

For general applications that don't push the CA3140 to it's limits, they should be interchangeable. You can always add an emitter follower current booster at the output if necessary.

Brian.
 
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    neazoi

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neazoi said:
But I cannot find source info for the tl071
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It is a very common single audio opamp, it is a TL081 that is selected for low noise. I have the datasheet for the TL072 dual opamp that is common in stereos and it has the spec's for the single, dual and quad versions.
Go to www.datasheetarchive.com where you can select the datasheet from the TI, the inventor manufacturer (with correct spec's) or from a copycat manufacturer (who frequently has errors in the spec's).

The input of the CA3140 works all the way down to ground in those circuits, the inputs of the TL071 work well down to about +3V or +4V but if the inputs go lower then the output suddenly goes high (phase reversal problem).
The output of the TL071 might not go low enough to turn off the relay.
 
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