LM6211: Maximum differential input voltage

Pavel Kobrisev

Part Number: LM6211

Hi everyone!
I'm using an OpAmp LM6211 in non-inverting mode. Recently I've noticed a parameter in datasheet that confused me a bit. It's about Vin differential (it's absolute maximum value is +- 0.3 V). Please, can you explain to me, what restrictions does it impose on the input signals? Or maybe there're some limitations on the output signal? I understand that OpAmp is tending to make the differential voltage between inverting and non-inverting inputs equal to zero, but I suppose that in some cases this rule doesn't work.
I really appreciate any help with this issue!

over 5 years ago

0 Tim Claycomb over 5 years ago

TI__Genius 15410 points

Hello Pavel,

The main thing this absolute maximum specification tells us is that the op amp has internal back to back diodes. Pulling the inputs apart by more than 0.3V causes the diodes to turn on and current to flow through them possibly damaging the device (unless the current is limited to less than what is stated in the abs max section).

There are only a few times these diodes will have an effect on the circuit. When the op amp is configured as a comparator and the inputs are pulled apart. Or when large transients are on the input, for example when a MUX switches causing the input voltage to go from -10V to +10V as explained in "MUX-Friendly Precision Operational Amplifiers".

Other than the two condition mentioned above the diodes typically will not have an effect on your circuit and will remain "off".

Thank you,

Tim Claycomb

0 Pavel Kobrisev over 5 years ago in reply to Tim Claycomb

Prodigy 20 points

Dear Tim, thanks a lot! Now it’s totally clear!

0 Tim Claycomb over 5 years ago in reply to Pavel Kobrisev

TI__Genius 15410 points

I'm glad I could help!

0 Ron Michallick over 5 years ago in reply to Tim Claycomb

TI__Guru*** 140166 points

Pavel,

In a linear circuit the input pins can separate (in voltage)...
if the input changes faster than the output can slew (see slew rate spec)
if the output goes to either supply rail (VOL or VOH). The loop is no longer closed and not linear.
during power up and power down in some applications.

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LM6211: Maximum differential input voltage