My arduino nano is powered
by a 11.1 v lipo battery.
Nano is connected to an mp3 shield
and the shield is in turn connected to a 3.7W amplifier
Both shields request 5 v for power supply, and
I connected both to nano 5V pin.
The circuit works (tested for just one minute), but I'm wondering if is it safe
for the amplifier to draw current directly from 5v arduino pin;
I'm not expert about amplifier, so I do not know how much current they draw.
The Adfruit site suggests to power the amplifier through batteries
and does not mention to connect to arduino power,
this is the reason of my question.
Note that the volume I'm using is set to minimum (very low; does it consume less current?).
Note that the volume I'm using is set to minimum (very low; does it consume less current?).
Right. It will draw less current at low volume.
And with normal program material you have a peak-to-average power-ratio of about 10:1, so if you're hitting 1W on the peaks, you are only averaging 0.1W (or less) average. That doesn't apply if you are putting-out constant tones... only with speech or music.
Generally, I wouldn't recommend running an audio amplifier from the 5V pin. But, if the voltage regulator on the Arduino is not too hot to touch, it's probably OK.
If the regulator is too hot to touch, you are probably better-off using a separate regulator for the amp, or better yet, get an amp that can run directly from the battery.