Various aspects are directed to communications, as may be implemented in an automotive network. An input transistor has a gate coupled to an input port and to a voltage-limiting circuit, connected between the gate and a power rail. The voltage-limiting circuit presents a voltage to the gate corresponding to a voltage on the input port and less than the supply voltage level, and clamps a gate-source voltage of the transistor. In a power-saving mode, current is blocked on the current path when the input port is at the supply or ground voltage levels. When the input port transitions away from the threshold voltage, the apparatus transitions to a wake-up mode in which current is no longer blocked in the current path and in which a wake-up signal is provided based on the voltage at the input port and a bias voltage.