LM3886 is NOT unity gain stable. There is a good Lm3886 model in TI’s version of TINA and you can play around w various gain settings to see what will cause it to go unstable
Have a look at Figure 49 of the LM3886 data sheet. You can expect about 60º phase margin with 20 dB gain. Note that the gain/phase curve is for a typical part. PM=60º is a good target if you want to ensure that the amp is stable even if you get an LM3886 that deviates from typical.
Also note that the gain/phase curve is measured with the output at mid-rail. The stability of the LM3886 gets worse as its output swings closer to the rails. That's why you see the extra components (Cc, Cf, Rf2) in AC Test Circuit #2 on page 5 of the data sheet.
Tom
Also note that the gain/phase curve is measured with the output at mid-rail. The stability of the LM3886 gets worse as its output swings closer to the rails. That's why you see the extra components (Cc, Cf, Rf2) in AC Test Circuit #2 on page 5 of the data sheet.
Tom
