The DAC I’m using cam work with any voltages with a delta of 20V. I figured that going with a delta of 10V and then quadrupling would be easier than generating 10V and -10V supply lines, but I’m already going to be generating 22V and -22V just for the opamps. Anyways, I guess I could change it to -3.25V to 6.75V which would give me the -13V to 27V Ian suggested. The opamps work with any voltage swing of 44V from my cursory reading of the data sheet.
My design is already complex enough for my first real design and first board I’d be ordering, so I’d like to keep it as simple as possible. I could add a -40V rail/bias that could be switched to, but then I’d need to add another demuxer, and that would just complicate the logic of the MUX_SEL line (lines if I add more demuxers). In addition, like I said, this won’t be a true universal programmer like the UniSite, but it will be able to do more than most.
Re: DIN41612: I saw that the UniSite uses this to connect the module to the system. I’m currently debating between that and a card edge connector like PCIe. For example, a PCIe 4x slot has 64 pins (48 pins with 16 left over for whatever) and a female connector costs just shy of $3 on DigiKey whereas DIN41612 requires a ~$2.50 receptacle (female) and a $3 plug (male). Now, I’ve never had a PCB manufactured before, so I don’t know how much card edge connectors cost, but from my understanding, it’s just exposed copper, no?
Also, I do plan to make this expandable, but maybe not right away. Maybe for a second revision? If I do do that, maybe a PCIe 16x for 164 connectors (160 pins with 20 driver boards with 4 leftover). If I go with DIN41612, it looks like the biggest standard size is 96 pins. I could use multiple connectors (2x64?), but that would just double the interconnect costs. I’m also wary of using actual pins as they could bend. A card edge connector doesn’t get bent pins. Anyways, that’s just for the interconnect to the actual DIP module.
For the interconnect on the pin driver boards, I was thinking of using standard 0.1" (2.54mm) 2x20 headers/sockets. This is partly evident in the schematic. From a quick Google search I did a while ago, they can handle about an amp per pin. With a maximum pin current of 100 mA, that wouldn’t be a problem. I could use a DIN41612 (48 pin) connector here too, but 0.1" headers/sockets are dirt cheap compared to DIN41612.