I am trying the DAC in the STM32F4, so far I am using just the HAL_set_value function and I am trying to get a clear output voltage. I am using the STM32F46 nucleo board.
I see that the ripple at the output (using the internal amplifier) is far highter than the mínimum voltage step (Vref=3.3V) so I put a 1nF capacitor at the output and the ripple gets much smaller (should I put just a capacitor or is better an RC filter?). On the other hand is not posible to differenciate between one code and the other since the overshoot at the begining is even bigger than the voltage difference between codes (when I jump for instance 500 codes).
What should I do in order to get better accuracy? I Will try to use a VREF of 2.5V generated by a external reference since 3.3V if too much for me. It is going to improve anything?
I see that there is a technical note about adding external amplifier and not use the internal one in order to increase the speed. In my case I am interested to be able to change the output at the level of milli volts or less. Is it posible? Should I put an external amplifier too? As a follower?
Actually in my aplicaction I need only a output range of 1V to 2.5V, but in the lower range I need more than 12bits so I am thinking to use that DAC2, divide the output by 8 with two resistors and use an AO to add the output of DAC2 to DAC1, doing so I could set a much more accurate low voltage but if the ripple and overshoots are so big… no way.
Any thoughts?
Thanks!
