OPA192: No Connect (NC) pins

F. Dennis Streetman

Part Number: OPA192

In aerospace, there is a no floating metal requirement, ex: unused pins are tied to ground through some resistor. What is TI recommendation on NC pins for the OPA192IDR? Leave floating or tie to GND through some resistor?

over 3 years ago

0 Raymond Zhang1 over 3 years ago

TI__Guru 53241 points

Hi Dennis,

TI recommendation is to place unused op amp in a linear operation mode, as suggested in the following post, see the blog post The Unused Op Amp—what to do? or the video How to terminate an unused op amp.

Please do not leave the unused input op amp pins floating or tight to ground, where the output of unused op amps are operating in saturated states.

If you have additional questions, please let me know.

Best,

Raymond

0 F. Dennis Streetman over 3 years ago in reply to Raymond Zhang1

Prodigy 60 points

Hi and Thank you. How about the NC. Some manufacturers state to tie them to GND other state floating. How about this part?

0 Raymond Zhang1 over 3 years ago in reply to F. Dennis Streetman

TI__Guru 53241 points

Hi Dennis,

If the op amp package is powered and NC is configured in one or more of unused op amp, then the op amp's output will be saturated, which is not recommended.

How about this part?

For OPA192, the input common mode voltage is specified near ground or V- pin. If unused op amp input is tied to ground, where Vref = GND as shown in the second image on the right, it is likely to be ok in a buffer configuration.

If you have additional questions, please let us know.

Best,

Raymond

0 F. Dennis Streetman over 3 years ago in reply to Raymond Zhang1

Prodigy 60 points

HI, So, how will connecting the No Internal Connect (NC) pins saturates the output? I am not interested in tying any inputs, only the no Connect pins.

0 F. Dennis Streetman over 3 years ago in reply to F. Dennis Streetman

Prodigy 60 points

Please reference the part number I listed in my beginning post.

0 Raymond Zhang1 over 3 years ago in reply to F. Dennis Streetman

TI__Guru 53241 points

Hi Dennis,

My mistake that I misunderstood your inquiry. NC connection has no internal connections in the SOIC or VSSOP packages. You can tie it to GND, For DO-160, the application has to go through Section 18.0 ( AF Conducted Susceptibility) to Section 23.0 (direct lightning) qualification tests. It is better to tie it ground/chassis instead of floating.

If you have additional questions, please let me know.

Best,

Raymond

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OPA192: No Connect (NC) pins