[sdiy] Shutdown on chip-amp

[Johannes Öberg]

Short version: I need to make a small mono power amplifier (probably a
LM386) shut down into some sort of low-power mode when not used, and
this will be controlled by a PIC. I'm a total newbie.

Longer:

I'm building a small batteryoperated door-bell out of an ISD2560
(lofi-sampler-on-a-chip) and a PIC. I guess I could have saved on
parts, but it's my own "design" so it's a bit of an overkill to get it
working.

Anyway, I'm trying to reduce the power consumption as much as
possible. I'm using the PIC in shutdown mode with interrupt-on-change
so it only draws power when you press the door bell button. The ISD
has a built-in power saving mode.

All this works so far.

However, while the ISD can drive a speaker directly, it is way too
quiet for my needs. Therefor I need to use an external amplifier. The
only one with built-in power down mode I can find readily available is
surface mount :-(

I looked at the LM386, but how do I make it power down? Can I just put
some kind of PIC operated switch on the voltage supply for the LM386?
Which one would you recommend? It doesn't matter if it's expensive
because this is going to be one-time quick-and-dirty fix.

Also, unfortunately, I'm short on time, and only have access to parts
from www.elfa.se (the only local electronics supply), aparts from the
random stuff I have at home of course.

BTW, the LM386 only gives out 325 mW. Is that enough? I have little
idea about these things, I have a 1W radio somewhere that is awfully
loud even at low pot settings, so that's why I figure 325mW would be
enough. Am I way off?

Thanks in advance.