The Adapter will be based on an ADV7611 from Analog Devices. The circuit will/should split a digital audio signal from a hdmi-stream.
The schematic is almost complete now. The first picture (1a) shows the ADV7611 with all connections. The USB connector for the power supply and the HDMI connector, both are safed with ESD protection IC's.
On the right side are the video and audio output. We couldn't find a good and cheap source for an optical SPDIF connector, so we changed it to Cinch. We've also choosed to make the videolines availiable, because there is pretty much potential for a further process.
The rest is pretty much the same, then in the reference design.
The second picture (1b) shows the power supply. The ADV7611 needs two different voltages (3V3 and 1V8) in five different nets. Each nets has a filter, which attenuates the disorders for at least 40db between 100MHz and 1GHz. Each connection pin needs also a 10nano and a 100nano capacitor as close to the pin as possible, to get the source as clean as possible.
status: layout in work