The MAX3238 true RS-232 transceiver achieves a 1µA supply current with Maxim’s revolutionary AutoShutdown Plus feature. When the device does not sense a valid signal transition on either the receiver or transmitter inputs within 30sec, the on-board power supply and drivers shut down. This occurs if the RS-232 cable is disconnected or if the transmitters of the con- nected peripheral are inactive. The system turns on again when a valid transition is applied to any RS-232 receiver or transmitter input, saving power without changes to the existing BIOS or operating system. The MAX3238 5-driver/3-receiver complete serial port is a 3V-powered EIA/TIA-232 and V.28/V.24 communications interface intended for notebook or subnotebook computer applications. A proprietary, high-efficiency, dual charge-pump power supply and a low-dropout transmitter combine to deliver true RS-232 performance from a single +3.0V to +5.5V supply. A guaranteed data rate of 250kbps provides compatibility with popu- lar software for communicating with personal comput- ers. The MAX3238 requires only 0.1µF capacitors in 3.3V operation. It is ideal for 3.3V-only systems, mixed 3.3V and 5.0V systems, or 5V-only systems that require true RS-232 performance. Receiver R1 has an extra, always-active output (in addi- tion to its standard output), which allows external devices, such as a modem, to be monitored without for- ward biasing the protection diode