LM324 / about unused pin

Sho Ogane

Other Parts Discussed in Thread: LM324

Hi all.

I have one question about LM324.
This device is quad circuit,but my customer use 2 circit only.

So please tell me how to treate unused pin(IN+, IN-, OUT)
My customer treats open.
Is it no problem?
If it is probrem, please tell me concern points.

Best Regards,
Sho

over 7 years ago

0 Ron Michallick over 7 years ago

TI__Guru*** 140106 points

Sho-san,

There are many ways to terminate unused amplifiers and many opinions on what is best.
Fortunately, most ways work for LM324

Never connect inputs to a low impedance node if this node can be negative relative to pin 11 (GND). Most often this to input to ground when GND is connected to a negative supply.

All three pins open works and slightly reduces ICC
One input to pin 11 (GND) and open on other input and output put output on one rail or the other.
Unity gain with non-inverting input set to pin 11 or some positive voltage is approved by almost all engineers.
Plus many more.

0 Sho Ogane over 7 years ago in reply to Ron Michallick

Genius 5575 points

Hi Ron san

Thank you for the response!

My customer uses Vcc- GND.
I have one question about your comment "All three pins open works and slightly reduces ICC"
Are all three pins IN+, IN-, Output ?

Best Regards,
Sho

0 Ron Michallick over 7 years ago in reply to Sho Ogane

TI__Guru*** 140106 points

Yes, those pins.

0 Sho Ogane over 7 years ago in reply to Ron Michallick

Genius 5575 points

Hi Ron san

Thank you for support everytime.

Best Regards,
Sho

0 Tsukui Yusuke over 6 years ago in reply to Sho Ogane

Guru 21930 points

Hi,

Could you tell me the recommended unused pin processing?
My customer is going to pin processing method described below.

・IN+ connect to GND
・Short the OUT and IN- pin
(voltage follower)

Is this all right?

Best Regards,
Yusuke/Japan Disty

0 Ron Michallick over 6 years ago in reply to Tsukui Yusuke

TI__Guru*** 140106 points

Tsukui-san,

This is acceptable.

Prefered unused LM324 op amp connection is covered here.

0 Tsukui Yusuke over 6 years ago in reply to Ron Michallick

Guru 21930 points

Ron-san,

Thank you for your kind support.
I understood your explanation.

Best Regards,
Yusuke/Japan Disty

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LM324 / about unused pin