HMCAD1511 Application Issue

There's  a Full-Scale issue in HMCAD1511, in actually if use up to over ±0.5V analog input(such as input ±0.8V), the ADC's code read out is 'FF'. But the customer read it out is not 'FF'. Does there any influence about the Fullscale register setting in data sheet shows? if it does , it's mean that 045V/0.55V is full scale @ fs_ctrl<5:0>:000000?