biasing LM386 output to 1/2 power supply

[fm101]

hi,

how can i bias output from LM386 to half the power supply(+5V)?

thanks

 

[betwixt]

It is already internally biased at half supply as long as you don't apply any DC to pin 3.

What exactly are you trying to achieve? The values you are using don't make sense and you shouldn't connect a capacitor directly across the output.

Brian.

 

[KlausST]

Hi,

Every IC comes with a datasheet. Look at the manufacturer for latest version.
You need to read it carefully.

Klaus

 

[fm101]

I am trying read in the audio signal output from LM386 into a microcontroller with range 0 to 5V. I knew that LM386 has internal bias but wanted the signal at the output vout as shown with center 2.5V. I tried using equal resistor divider at the out(vout) but did not work.

The capacitor of 0.047uF I used because in the datasheet it is used in there(0.05uF) as shown in the attached picture. I used 1uF instead of 250uF because it also worked, the sound is clean and acceptable.

 

[betwixt]

The 2.5V offset is already there but being blocked by the output capacitor. Feed your microcontroller directly from pin 5 and it will work.

You should be made aware that the LM386 is not a particularly good choice for this because it is designed to provide high current into a low impedance load (a loudspeaker). A rail-to-rail op-amp will give you better performance and it's output will not have the range limitation of the LM386.

Brian.

 

[fm101]

thanks...i think lm386 is good only for audio driving speaker, it better to leave it and go for other op-amps

 

[KlausST]

Hi,

indeed LM386 is no OPAMP at all, the datasheet calls it "Low Voltage Audio Power Amplifier".

But yes, an OPAMP seems to be more suitable.

Klaus