I was under the impression that in a DAC, once it was set for a value, the corresponding switch will never change its state on its on. But now that i see strange voltage hops on my selfbuilt AN86-dual-DAC-circuit im doubting that. See the attached pictures, it seems to me that these are jumps corresponding to a change in the LSB of the MSB-DAC.
Of course in the end the AN86-circuit is closedloop and the error can be disregarded, but it just interests me. Maybe someone can contribute on this topic.
My circuit consists of a DC1684A-B 16-Bit-Dual-DAC-board, summed by 0,1% metal-film smd-resistors and a good OP i had laying around (OPA2277 i think). Circuit and DAC-Board of course thermally stabilized for hours and data-control connector disconnected after the 5,0V value was set.
Hello,
at least the upper trace looks like popcorn noise (of the voltage reference).
Which voltage reference does the board use?
With best regards
Andreas
Hello,
at least the upper trace looks like popcorn noise (of the voltage reference).
Which voltage reference does the board use?
With best regards
Andreas
That top trace is nearly 15 hours, those dips are several minutes long.
It uses the standard populated LTC6655CHMS8-5.
What are you using for the +/- 15V supply?
Also, do you have a way of logging temperature? It looks like the meter is tracking ambient temperature.
Hello,
not uncommon for certain references.
I have this at least on one sample of MAX6350.
(plot has 6 minutes total time).
With best regards
Andreas
It uses the standard populated LTC6655CHMS8-5.
Thermally isolated?
The 6655 heats quite a lot.
What are you using for the +/- 15V supply?
I hope the 6655 has a lower power supply voltage than 15 V.
With best regards
Andreas
could also be mechanical stress from PCB.
I have measured 60-70uV change by applying mechanical stress to a PCB with
LTC6655BHMS8-5 mounted in a U-slotted area.
with best regards
Andreas