How much current can an opamp source


How do you figure out how much current an opamp can source from the datashe et? I'm looking at this instrumentation amplifier (datasheet link below) an d the only things I find that relate to current is


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Maximum Input Current to any pin is 5mA - which makes me think "any" includ es power pins, which means this thing can't source more than 5mA (since it can't take in more than 5mA)

and then there's this graph Figure 10 page 6, which shows Output Voltage Sw ing vs Output Current, this thing goes out towards 20mA... i'm not sure wha t this graph is telling me, but my guess is that it shows the output voltag e sag as more current is sourced...

I feel like I've run into this problem before, what's the goto thing to loo k for in an opamp datasheet to find out how much current the part can sourc e?


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"Swing" is defined in the data with a 10k Load. Which also refers you to Figure 10, swing versus load current. It's meant as a current sensor, _not_ as a general purpose OpAmp. ...Jim Thompson

| James E.Thompson                                 |    mens     | 
| Analog Innovations                               |     et      | 
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Jim Thompson

I think the 5ma spec is a poorly worded attempt to describe the current injection limit, i.e. for latch up. Then again, nobody would ever release a part that only does 5ma. 50ma would get the evil eye at most companies.

I have to say I'm not impressed by this datasheet. There are plenty of high side current sense chips out there. Maybe there is one with a better spec.

Note that when a datasheet specifies a source/sink current limit, it is usually with the driving device turned on to the maximum and the pin at the other rail with an ammeter in between. Source/sink limits do not indicate linear operation. Often the amplifier will have significant linearity error before reaching the current limit.

Basically the manufacturer has to draw the line somewhere, if only to satisfy electromigration limits in layout. If you twist their arm, the current spec is over an "indefinite" time. And indefinite does not equal infinite.

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