65539 = 0x10003 = 1 000<b><u>0 0000 0000 0011</u></b>
                  | <->|<------------>|
                  |  |  13  bits  used
                  |  |    by the chip
                  |  |
                  |  +-- 3 DON'T CARE bits ignored by the chip
                  |
                  +-- 1 excess bit that won't even fit at all!