The MAX3218 RS-232 transceiver is intended for battery-powered EIA/TIA-232E and V.28/V.24 communications interfaces that need two drivers and two receivers with minimum power consumption from a single low-voltage supply. It provides a wide +1.8V to +4.25V operating voltage range while maintaining true RS-232 and EIA/TIA-562 voltage levels. The MAX3218 runs from two alkaline, NiCd, or NiMH cells without any form of voltage regulator. A guaranteed 120kbps data rate provides compatibility with popular software for communicating with personal computers.
Supply current is reduced to 1µA with Maxim's new AutoShutdown feature. When the MAX3218 does not sense a valid signal level on the receiver inputs, the on-board power-supply and drivers shut down. This occurs if the RS-232 cable is disconnected or if the transmitters of the connected peripheral are turned off. The system turns on again when a valid level is applied to either RS-232 receiver input. As a result, the system saves power without changes to the existing software. Additionally, the MAX3218 can be forced into or out of shutdown, under logic control.
While shut down, all receivers can remain active or can be disabled under logic control, permitting a system incorporating the CMOS MAX3218 to monitor external devices while in low-power shutdown. Three-state drivers are provided on both receiver outputs so that multiple receivers, generally of different interface standards, can be on the same bus. The MAX3218 is available in 20-pin DIP and SSOP packages.
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