A13 - external audio amplifier

[ddemarco]

Hi everyone,

I'll soon be starting a "Sonos++" networked audio player project, and I'm confused about the headphones output on the A13-SOM-512. I'm unsure about the role of the HPCOM pin, and whether it should be used when using an external amplifier. The amplifier will of course share the same GND reference as the A13-SOM-512.

So, should I simply use HPOUTR and HPOUTR decoupled with a capacitor and leave HPCOM unconnected? Is there anything else needed?

Thank you!

[Gerrit]

I'm unsure about the role of the HPCOM

HPCOM is a DC offset to make it possible to have a negative and positive voltage against it without the use of a capacitor, safe for a head phone because its normally not also connected to the GND of the board.

So, should I simply use HPOUTR and HPOUTR decoupled with a capacitor and leave HPCOM unconnected

Yes that is one option, the other one is connect HPOUTR and HPOUTR without a capacitor and connect HPCOM with the ground of your amplifier, and use a capacitor between GND and the ground from the amplifier, (- side on GND) to prevent a hum when the board is switched off.