The SP3221E is a RS-232 transceiver solution intended for portable or hand-held applications such as notebook and palmtop computers. The SP3221E has a high-efficiency, charge-pump power supply that requires only 0.1F capacitors in 3.3V operation. This charge pump and low dropout transmitters allow the SP3221E device to deliver true RS-232 performance from a single power supply ranging from +3.3V to +5.0V. The Auto-Online feature allows the device to automatically "wake-up" during a shutdown state when an RS-232 cable is connected . Otherwise, the device automatically shuts itself down drawing less than 1A.