Damian,
The AFE5807 and AFE5808A both have a maximum Resolution of 14-bit. However, the AFE5807 is a lower-power version of the AFE and it defaults to 12-bit mode by truncating the 2LSBs. You may also see 16-bit mode, but this means the ADC only adds two zeros for two LSBs in order to provide a convenient data format. See pg. 27
Thanks,
Chuck Smyth