LMV612: Is there an op amp pin floating in the dual channel, which will cause the normal operation of the op amp to fail?

rengui sun

Part Number: LMV612

LMV612 only uses A, B is not used, but forget to process B when design, resulting in +INB, -INB, OUTB are all floating state, what will result in this, A will be invalid?
The product is about to be released and does not want to modify the principle and PCB.

over 5 years ago

0 kai klaas69 over 5 years ago

Guru 140200 points

Hi Rengui,

this cannot be recommended! The unconnected OPAmp can oscillate and this can have consequences for the connected OPAmp. Also, the supply current can increase.

Kai

0 Tim Claycomb over 5 years ago

TI__Genius 15410 points

Hello Rengui,

Kai is correct. This is not recommended! The unused amplifier will be in an unknown state causing it to potentially oscillate and/or increase the quiescent current.

The blog, The Unused Op Amp - what to do?, explains our recommended configurations for an unused amplifier.

Thank you,

Tim Claycomb

0 rengui sun over 5 years ago in reply to kai klaas69

Intellectual 680 points

Thank you for your reply. What I want to ask is that the connection op amp will work abnormally or fail? I can bear the increase in power consumption.

0 Tim Claycomb over 5 years ago in reply to rengui sun

TI__Genius 15410 points

Hi Rengui,

My main concern is that an increase in power could damage your device due to an increase in temperature. I do not recommend going into production with the design as is.

The increase in temperature may also effect the performance of the properly configured op amp and possible reduce the life of the device because it will operate at an increased temperature.

Thank you,

Tim Claycomb

0 rengui sun over 5 years ago in reply to Tim Claycomb

Intellectual 680 points

Do you have feedback that the op amp pins are floating and causing failure?

I only used A of LMV612, and the 3 pins of B are all floating.

Does TI have op amps that are compatible with the LMV612 package, but remove the B op amp?

This way I don't need to modify the principle and PCB.

thank you!

0 Tim Claycomb over 5 years ago in reply to rengui sun

TI__Genius 15410 points

Hi Rengui,

Even though all pins (input and output) of channel B are floating the supply voltage is still connected to channel B op amp.

I am not aware of a device that has the same pin out as the LM612 but only uses channel A.

Thank you,

Tim Claycomb

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LMV612: Is there an op amp pin floating in the dual channel, which will cause the normal operation of the op amp to fail?