DAC output has 60 mv of offset with Ouput buffer disabled

[hooman14]

Posted on February 14, 2011 at 21:08

DAC output has 60 mv of offset with Ouput buffer disabled

[hooman14]

Posted on May 17, 2011 at 14:24

Any thoughts? suggestions? would appreciate the help.

Thanks!

[hooman14]

Posted on May 17, 2011 at 14:24

Thanks John for your help.

It was my output buffer. it wasn't disabled. I was setting the value to DISABLED(0) which really enables the DAC output buffer.

silly me.

Thanks again.

[John F.]

Posted on May 17, 2011 at 14:24

What are you using to measure this? What are you using as a ground (0V) reference? Have you grounded ALL the microcontroller GND pins? Do the GND pins measure as 0V? Do the other digital outputs GPIO etc. also have an offset? It sounds like your ground isn't good or you are using a poor reference ( such as the power supply 0V which may not be at the same potential as the 0V on the PCB ).

and ... are you sure you're disabling the buffer? Can you test that by loading the output and enabling / disabling the buffer and looking for a voltage change?