The MAX3318E/MAX3319E achieve a 1A supply current using Maxim's revolutionary AutoShutdown Plus feature. These devices automatically enter a low-power shutdown mode when the RS-232 cable is disconnected or the transmitters of the connected peripherals are inactive for more than 30 seconds. They turn on again when they sense a valid transition at any transmitter or receiver input. AutoShutdown Plus saves power without changes to the existing BIOS or operating system. The MAX3317E also features a 1A shutdown mode that can be entered by driving SHDN low. The MAX3317E's receivers remain active while in shutdown mode, allowing external devices such as modems to be monitored using only 1A supply current.