# Designing a circuit with a LM386 amplifier

I'm designing a circuit an I want to use the LM386 audio amplifier. Before designing, I'm going through the whole datasheet, I've seen that VI is from -0.4V to 0.4V :

Here is the first typical application :

I'm just wondering if Vin is what they call VI just before ? Or is it a different value that will be higher since it will be divided by the potentiometer ? I don't find the datasheet very clear about that.

• VI is the voltage at the actual pins (2 and 3) of the LM386. Sep 29 at 14:31
• Keep in mind that minimum gain is 20. If the pot is wound all the way to the top, an input $V_{in}$ with peak amplitude greater than 0.4V will certainly cause distortion at amplifier output (and likely will distort with even lower $V_{in}$ ) Sep 29 at 14:49
• Bibibou: I'd suggest no more than 0.3V peak at input. Your question's schematic doesn't show gain...be aware that adding a capacitor in the feedback path (between pin 1 and pin 8) can increase gain from 20 up to 200. In that case, your input peak amplitude shouldn't exceed 0.003 V if you expect output to remain undistorted. Vcc also has an influence on the amplitude where distortion begins. Sep 29 at 15:21
• You said you have an audio signal that comes from an ADC. An ADC is used to convert an analog voltage to a digital value - you don't want to feed that digital value into an LM386 as the LM386 wants an ananlog audio signal as input. Sep 29 at 15:31
• The LM386 works well driving an 8 ohms speaker when its supply is 6V or 9V. When a 12V supply is used then its output is distorted and it heats a lot when driving an 8 ohms speaker but it can drive a 16 ohms speaker with up to 0.5W into the speaker and with 0.5W of heating. Sep 29 at 17:50