Hello eevblog members,
i would like to introduce you one of my new hobby project. Work name is simply uDAC. I had some LTC circuits in my drawer so... i want to test it. It is first version and i want to continue with this project and made some "adult" DAQ. NI DAQ are nice, but they are quite expensive and i need to educate myself
This project will be open source, if it will works
Basic idea : take ADC, DAC, reference a put it in one board, isolated power supply and SPI interface.
ADC is older, but still OK 24bit LTC2410
DAC - LTC1650
Main reference - LTC 6655 2V5
SPI isolator - SI8662AB-B-IS1
power supply DC/DC AIMTEC 5V to 2x7,2V
positive supply rail LDO - ultra low noise high psrr LP38798SD
negaitve supply rail LDO - ADP7182A 5V fixed (very hard to find
)
Steps :
1) Find,collect and solder all parts- DONE
2) Do some long time stability measurements on supply rail and reference. Check electromagnetic emissions and noise spectrum on supply rail, tune supply filter.
3) Write some test code to STM32
4) Do some stability measurements on DAC and ADC. Evaluate ENOB, errors, nonlinearity atc.
5) Make some changes for better results.
I will put results here. It take some time because i dont have GPIB controller and cable to my HP34401 so i must take it to my university lab.
After all steps i post here altium design files, C test code and all results.
At the end, excuse my english level i am not an native.