ProtoDAC TDA1387 X8 project

[hifinet]

I really don't think it matters much. I copied the values from another design (which actually used 470R). I left them at 430R so that someone could buy a bunch of resistors, all the same value, and use 430R for the I2S and the I/V resistors. Their purpose is to reduce noise on the lines from reflections. CANBUS uses 120R. I2S are voltage signals without any significant current, so there isn't a significant voltage drop. ProtoDAC will work up to 384kHz sampling with the 430R I2S resistors, so I didn't see a need to change them.

Looking at the TDA1387 datasheet page 7, the max leakage current is 10 microamps. So with a 24R I2S resistor, the maximum voltage drop is 0.24mV. With 430R it's 4.3mV. Digital 1 of 5V would be 4.99976V with 24R and 4.9957V with 430R.