My CPU uses a 2.5V supply, but the MAX3420E uses a 3.3V VCC supply. Do I need external level translators?
No, the MAX3420E contains internal level shifters. A VL pin powers the internal logic and serves as the logic reference voltage for the SPI and IO pin signals. For a 2.5V interface, connect your 2.5V supply to the VL pin. The VL pin can actually operate with a range of voltages from 1.7V to 3.6V. If the controller uses 3.3V, tie VL to VCC.
