Author Topic: Why use the inverting input on the 386?  (Read 1177 times)

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Why use the inverting input on the 386?
« on: August 02, 2010, 06:38:53 PM »
I've noticed that in a number of the 386 amp designs, the 386's inverting input is used, but (if I remember correctly) in all of the designs in the datasheet, the non-inverting input is used.

What is the advantage of using the inverting input? Does it just make the layout easier?

brett

Re: Why use the inverting input on the 386?
« Reply #1 on: August 03, 2010, 03:17:31 AM »
Hi
Quote
What is the advantage of using the inverting input?
Inverting stages can help with feedback (ie any "leakage" that finds its way back to an inverting input cancels rather than reinforces the signal).

Also, non-inverting stages are sometimes used where the input stage has high impedance (such as JFET op-amps).  Because the 386 has low input impedance, this advantage of non-iverting stages isn't there.

there might be other reasons too...
Brett Robinson
Let a hundred flowers bloom, let a hundred schools of thought contend. (Mao Zedong)

jasperoosthoek

Re: Why use the inverting input on the 386?
« Reply #2 on: August 03, 2010, 05:03:09 AM »
Several years ago I built a little amp for a battery powered speaker. It has two lm386s, one connected in inverting mode the other in non-inverting mode. That way I created a bridge tied load amplifier. It worked perfectly. http://en.wikipedia.org/wiki/Bridge-tied_load

I don't know why people apparently favor the inverting input, both are possible.
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