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QD4 Internal Voltage Reference Calibration

Question asked by Thomas Walsh on May 18, 2009
Latest reply on May 21, 2009 by Celso Monteiro

The QD4 series contains a built-in voltage reference that is better than 1% accurate.  Not bad, but I have an application that could benefit from better accuracy.  I am wondering if anybody has tried calibrating the reference with a trim value in software, on a chip-to-chip basis.  I think this could reduce the ADC's absolute voltage measurement error by a factor of 2-3.


Our factory uses a "beehive" gang programmer.  I am thinking we would need to modify it to

1) place a highly-accurate reference voltage on one of the inputs,

2) program the chip with a measurement program that can communicate a trim value back to the PC,

3) read the trim value back to the PC

4) Have the PC program each chip with a binary containing the proper trim value (probably only 10 or so values would come into play).


If anybody has suggestions on how to accomplish items 2-4,  or if you know of a reason why this whole thing will never work or be beneficial, or if you've tried this yourself and succeeded, please let me know.