LM386: Pin 7 bypass cap: needed or not for my application?

Zotin Khuma

Part Number: LM386

I want to use the LM386 as part of an all-analog, all-linear circuit that does not involve RF. The power supply will be a linear (non-switching) one regulated by a 7812 IC. Pin 4 is connected to the regulator by about an inch of copper track. Am I right in thinking that omitting the bypass cap on pin 7 will not make any noticeable difference?

over 6 years ago

0 Ivan Salazar over 6 years ago

TI__Guru** 111265 points

Hi Zotin,

You can leave the footprint available and test its performance without bypass capacitor. If it results to be necessary then you can just populate it.
As you can see in the data sheet, power supply rejection will be affected if Bypass capacitor is not used.

Best regards,
-ivan Salazar
Applications Engineer - Low Power Audio & Actuators

0 kai klaas69 over 6 years ago

Guru 140200 points

Hi Zotin,

it's not wise to omit the bypass cap. It enormeously increases the stability of LM386.

Kai

0 Zotin Khuma over 6 years ago in reply to Ivan Salazar

Prodigy 120 points

Thanks for the quick reply. My main concern here is whether I could omit the footprint to make the layout as compact as possible rather than about saving a few cents on the cost of the capacitor. The minimal configuration on the datasheet doesn't use it and the others show it as optional.

I've used the LM386 a few times in the past and always included the bypass capacitor. I was wondering if I could get away with not using it. But if you advise against it, I guess I'll just have to make room for it.

0 Ivan Salazar over 6 years ago in reply to Zotin Khuma

TI__Guru** 111265 points

Hi Zotin,

Thanks for your comments. If you have additional questions please let us know, or you can start a new post.
I'll consider this closed for now.

Best regards,
-Ivan Salazar
Applications Engineer - Low Power Audio & Actuators

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LM386: Pin 7 bypass cap: needed or not for my application?