is only 1.1V not 1.25V,and the voltage of Pin 5, is only 0.3~0.6V.
From what I remember of the AD73360 eval software the reference is only enabled
while the part is taking samples. What you may be seeing is that when the
software is run the AD73360 powers up (RESET goes high), the reference is
enabled (REFOUT and REFCAP should go to 1.25V/3V), about 6000 samples are taken
and uploaded to the PC. The AD73360 is then reset to stop the sampling.
I think REFCAP will remain somewhere around 1.25V because there is a decoupling
capacitor holding the charge.