What's the difference MPN MAX17632AATE+ MAX17632BATE+?

The MAX17632 is a synchronous step down converter that is available in 3 different versions with an input of 4.5 - 36 volt 2 Amps, The 3 versions as denoted by the suffix, reflect their respective outputs as listed below.

MAX17632AATE+ 3.3V fixed output
MAX17632BATE+ 5.0V fixed putput
MAX17632CATE+ Adjustable output

Please note that the MAX17632 is only available in a TQFN 3mm x 3mm package and an Evaluation kit is available.

Here is a link to the datasheet.