I'm designing a general purpose Arduino shield pcb and right now I'm struggling to find a proper ground layout.
ICs on the board: 12->5V and 12->10V @5A switching DCregulators, several H-Bridge motor drivers (rated at a max 1.8A), a TEC driver (rated at max 3-6A ),a pair of octal-switch SPST, a pair of shift registers and a DAC among some op-amps, FETs and BJTs.
I'm following Ott's guide for grounding mixed signal pcbs. I've got the basics down, but the main issue is that the TEC driver's datasheets implies the existence of a Power Ground on the PCB and considering all the large currents flowing out of the DC regulators, I realize it can be quite relevant. I'm also not sure if the motor drivers should be part of this power ground plane (the 10V rail is supposed to power DC motors driven by the H-Bridges).
My questions: are the digital ICs (Shift registers, SPST switches, digital side of the DAC) really that noise sensitive that a noisy ground would compromise their behaviour? (I suspect only the DAC). If that was not the case, I could just use a common Digital/Power ground.
I'm considering a power ground (DC regulators, Motor drivers) with two bridges: to digital ground (SRs, Switches) to an analog ground (TEC driver), and additionall a bridge between the digital ground and a second analog ground (with the DAC and analog input pins). Would there be any ground loops with such a configuration?