Input Range for Combo Box

Hello,
I have a Range from cell A1 to A3 named RAW which contains departments (Finance, Marketing, Production) and this is getting populated in combo box as list.
I have another combo box (2nd combo box), in which the list should appear based on the input in combo box1. eg. If i select Finance in combo box 1, then in combo box 2 list should show only AA, AB and AC, if I select Marketing in combo box 1, then in combo box 2 list should show only BA, BB and BC.
AA, AB, AC, BA, BB, BC are in cell B1 to B6.

How to create the input range for combo box 2 based on combo box1?