How to configure an unused opamp

If you have a dual channel opamp, but only uses one of the channels, it’s important to configure the unused opamp correctly. Leaving either the input or output pins floating can lead to unpredictable behaviour.

Single supply

If you are using a single supply, connect the non-inverting input to a voltage-divider from the supply rail. Or connect it to a reference voltage that is within the specified common mode range. This ensures that the input voltage will be within the common mode range by setting it to mid-supply.

Connect the output to the inverting input to provide negative feedback, allowing the op amp’s output to follow the input and operate in its linear region.

Unused opamp single supply rail

Split supply

In the case of split supply rail, just connect the non-inverting input to ground.

Connect the output to the inverting input to provide negative feedback, allowing the op amp’s output to follow the input and operate in its linear region.

Unused opamp split supply rail

References

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