I was considering making my own uCurrent after the latest batch sold out so fast, but integrating it into a power supply is a brilliant idea
![Cheesy :D](https://www.eevblog.com/forum/Smileys/default/cheesy.gif)
I too came across all the microchip ADC/DACs due to their low prices, but I was disappointed to see no quad input ADCs from them with I2C
![Sad :(](https://www.eevblog.com/forum/Smileys/default/sad.gif)
Using I2C is great from a modularity point of view. You can very easily expand to a dual/triple output supply without needing more microcontroller I/Os, and the code change is trivial (simple address change - no overlapping pins).
The Analog Devices AD7998 seems perfect for a dual output supply. Once setup you can read all 8 channels with one address/write byte + command byte, followed by one address/read byte and 16 read bytes (it just samples ch1, ch2, etc in order). For each output, I would sample current, uCurrent, output voltage BEFORE an output enable mosfet, and Vsense (either seperate terminal, or on the actual output connector, or switchable...). The AD7994 is a 4ch version.
Input voltage could simply be measured using the microcontrollers ADC as high accuracy isn't necessary.
For a i2c DAC I was going to go with the microchip MCP4728. Has an internal 2.048v Vref with a selectable x1 or x2 gain (handy for extended voltage ranges) but its accuracy is only +/- 2% with 45ppm/C...
For a micro I was going to go with a PIC18F4550 for a few reasons.
1) I've used them in the past
![Tongue :P](https://www.eevblog.com/forum/Smileys/default/tongue.gif)
2) Hardware i2c, serial, and USB2.0 (all usable at once I believe)
3) Microchip USB stack and bootloader make it incredibly easy to do firmware updates over usb, or emulate a COM/Serial port over USB. Their framework and examples make it incredibly easy to get USB comms working.
4) Plenty of I/O leftover for "stuff"
Also comes in a DIP40 package although some of the other parts i've chose are SMD parts only. I'll be going for TQFP package myself since I've got a few of them leftover from a previous project.
I figured with I2C, you could build modular boards that have all the DAC/ADC/Vreg stuff, and a single control board. Thanks to Dave making his design open source other's can do things a little bit different
![Smiley :)](https://www.eevblog.com/forum/Smileys/default/smiley.gif)
Also, for the main power supply, would it be reasonable to use something like an 15-18V switchmode supply? I want something I can mount internally instead of using an external jack, and AC transformers are so expensive!
Any thoughts, comments, glaringly obvious silly things?