I'm trying to get my head around the DAC-08. I have so far come up with this circuit as a test:
However - it is not producing the results I would expect.
Here's what it does:
U1 created a square-wave clock signal to drive U2 which is a binary counter. The output of this heads into the DAC-08's (U4) data inputs. I have buffered the signal through U3 because I noticed during my experimentations that the outputs of U2 don't always have the exact same voltage. U3 should be redundant in this circuit. I had it there mainly when I replaced the DAC-08 with am R/2R ladder to test the rest of the circuit. The output of the DAC-08 is then fed through an op-amp in voltage follower mode.
Now, I'd expect a nice triangle wave form out of this, and that is (roughly) what I got with the R/2R ladder.
However, what I get from the DAC-08 is something more like this:
I have tried playing around with the order of the data pins, and it seems to always come up with the same (or similar) waveform. Now, I'm new to the DAC-08, and I don't fully understand what all the pins do - and the data sheet fails to mention it either, so there is something I am missing. I have gone through a number of example applications, but none of them have shed any light on this.
Does anyone have any experience with the DAC-08? Can anyone point out where I am going wrong?