We have build some prototypes of a new product containing the STM32L486 (UFBGA132 package). The VREF+ pin is buffered with 1µF and 100nF. I measured the reference voltage with two different calibrated multimeters. The results differs from 2038mV to 2042mV on different boards. The datasheet gives a range from 2046mV to 2049mV. "Guaranteed by test in production."
VDDA is 2.8V
VDD is 1.8V
I am able to change the reference output voltage using the VREFBUF_CCR register but the reference manual says that the content of the register will be initialized automatically with the production values from flash at reset.
Can anyone explain the difference?
Where is the flash location with the production test results?