Check out this review from ameriDroid customer, Tom M. If you'd rather watch a brief video introduction, check out the video at the bottom of this post.
I had a chance to play with the little amplifier this weekend. The SW pin is something that is actually a selling point [...]
I followed it to pin 12 which is an on-off feature in the datasheet, when that input is grounded it turns off the unit completely. I tested it at 3.7 volts with (2) 3 watt 4 ohm speakers, I put a frequency to it of 700hz at .4V, and that input had just shy of system voltage on it, when grounded it literally shut the whole thing down and current draw went from 200ma down to 0ma.
I redid the test at 4.9V with consistent results, the input showing just below system voltage and drawing no current when grounded.
It's actually so sensitive that if you touch the input it will shut down, so I simulated a gpio @ 3.7v, using a 4001 diode so the amp couldn't sink current from the gpio and it works perfect.
The sw pin is an ideal way to switch the amp off and on with a gpio.
I also installed a 220 microfarad 10 volt capacitor on the back where it has provisions for a stiffening capacitor, nothing that I did seems to make a difference with or without the capacitor but I was not playing music so it may be beneficial, I didn't get any tell tale pop when power was introduced to it either so the stiffening cap appears to have no negative effects.
I followed it to pin 12 which is an on-off feature in the datasheet, when that input is grounded it turns off the unit completely. I tested it at 3.7 volts with (2) 3 watt 4 ohm speakers, I put a frequency to it of 700hz at .4V, and that input had just shy of system voltage on it, when grounded it literally shut the whole thing down and current draw went from 200ma down to 0ma.
I redid the test at 4.9V with consistent results, the input showing just below system voltage and drawing no current when grounded.
The sw pin is an ideal way to switch the amp off and on with a gpio.
I also installed a 220 microfarad 10 volt capacitor on the back where it has provisions for a stiffening capacitor, nothing that I did seems to make a difference with or without the capacitor but I was not playing music so it may be beneficial, I didn't get any tell tale pop when power was introduced to it either so the stiffening cap appears to have no negative effects.
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