The MAX221 achieves a low 1A supply current with Maxim's revolutionary AutoShutdownTM feature. AutoShutdown saves power without changes to the existing BIOS or operating system by entering lowpower shutdown mode when the RS-232 cable is disconnected, or when the transmitter of the connected peripheral is off. The MAX221 wakes up and drives the INVALID pin high when an active RS-232 cable is connected, signaling the host that a peripheral is connected to the communications port. The MAX221 is available in a 16-pin SSOP package as well as a 16-pin TSSOP that uses 50% less board space than a 16-pin SO. For an equivalent RS-232 transceiver with enhanced 15kV ESD protection, refer to the MAX221E data sheet.