The MXL1543 is a three-driver/three-receiver multiprotocol transceiver that operates from a +5V single supply. The MXL1543, along with the MXL1544/MAX3175 and the MXL1344A, form a complete software-selectable data terminal equipment (DTE) or data communication equipment (DCE) interface port that supports the V.28 (RS-232), V.10/V.11 (RS-449/V.36, EIA-530, EIA-530A, X.21), and V.35 protocols. The MXL1543 transceivers carry the high-speed clock and data signals while the MXL1544/MAX3175 carry the control signals. The MXL1543 can be terminated by the MXL1344A software-selectable resistor termination network or by discrete termination networks.

An internal charge pump and a proprietary low-dropout transmitter output stage allow V.11- , V.28- , and V.35-compliant operation from a +5V single supply. A no-cable mode is entered when all mode pins (M0, M1, and M2) are pulled high or left unconnected. In no-cable mode, supply current decreases to 0.5µA and all transmitter and receiver outputs are disabled (high impedance). Short-circuit current limiting and thermal shutdown circuitry protect the drivers against excessive power dissipation.