Output drive circuit tolerant of higher voltage signals

摘要

An output drive circuit enables both 5V and 3V devices to be connected to the same bus, without exposing the 3V devices to damage from the 5V signals on the bus. The 3V devices utilize 3V output drives that are tolerant of the 5V signals on the bus. The tolerance is achieved by a circuit design which adjusts internal voltages depending upon the external voltage on the bus. The internal voltage adjustments prevent transistor voltage limits from being exceeded and hence prevent damage from occurring.