I checked the voltage with DVM: 4.96V; Also strange that the voltage at 4095 is lower than at 4000...
I guess it should be 4.96V .
A few minutes later:
address(hex)=61 lookup=0 lookupWa=200 an.value=497 voltage=2.43
address(hex)=61 lookup=1 lookupWa=400 an.value=505 voltage=2.49
address(hex)=61 lookup=2 lookupWa=800 an.value=520 voltage=2.43
address(hex)=61 lookup=3 lookupWa=1000 an.value=511 voltage=2.56
address(hex)=61 lookup=4 lookupWa=2000 an.value=509 voltage=2.49
address(hex)=61 lookup=5 lookupWa=3000 an.value=745 voltage=3.62
address(hex)=61 lookup=6 lookupWa=4000 an.value=893 voltage=4.29
address(hex)=61 lookup=7 lookupWa=4095 an.value=891 voltage=4.32