Bit of a thread revival here - I've been flat out with other things for the last couple of weeks, so have let this slip. So, my board will have two separate grounds - one for digital, one for analog.
On the subject of classifying ICs, I'm just listing mine out and have a few left which I can't quite justify whether its analog or digital.
- h-bridge, as it takes digital signals but ultimately the waveform across the output terminals are not truly digital due to the motor inductance
- stepper motor driver, again - digital in, not truly digital out
- switching MOSFETs and IGBTs, for switching inductive loads, so again - analog or digital?
- gate drivers, hmm.
- discretes such as TVS diodes?