Hi Kobayashi-san,
I believe that you are asking the reason why AVDD 3.3V decreased by 40mA after disabling output channel C and D. The reason for this is that the power consumption level that I gave you before is based on 20mA full-scale output current for each channel. By disabling output channel C and D, you save 20mA constant current draw for 2 channels, thus saving 40mA.
Please let me know if I have answered your question correctly.
-Kang