I need to get 0-4.096V from ATmega88. I will most likely use ADR444BRZ reference (+/-1.6 mV, max current +10mA/-5mA).
http://www.farnell.com/datasheets/1048061.pdfI found two options using I2C DAC or using PWM + Level shifter +Low pass filter.
a) using 10 bit I2C DAC
I think high end are expensive. They have bigger offset error and it will be harder to use. I will be using EU Farnell for components and for now I can't find anything suitable.
b) using Level shifter and LPF
I can't find good high performance Level shifter. PMW will most likely work on 16 or 20 MHZ. It need to have low resistance to GND and low resistance to V+. Also use less than 5mA given by Vref.
MCU will work on 5V. It can't be powered with Vref, it can use up to 9mA. Op amp will have +/- 2nA input current max.
Any suggestion?