An apparatus for use in an automotive network having a plurality of communication circuits and a battery that powers the communication circuits, the apparatus comprising: a first circuit (213, 214) configured and arranged to generate a bias (VREFH) voltage by dividing a supply voltage level provided on a power rail by a battery, relative to a ground voltage level provided on a ground rail; and a second circuit, having a current path coupled between the power rail and the ground rail, the current path comprising a first transistor with a gate coupled to an input port, wherein the first transistor is configured to pass current for generating a wake-up signal in response to transitioning of a voltage level presented on the input port; the second circuit further comprising an impedance circuit (211, 212, 215) connected between the gate and the power rail and configured to present a voltage level to the gate of the first transistor, wherein the voltage level presented to the gate of the first transistor corresponds to the voltage level presented on the input port and is less than the supply voltage level; the impedance circuit comprising: a second transistor connected in series between the supply voltage and the first transistor and having a gate connected to the bias voltage; and a resistor connected in parallel across a source and a drain terminal of the second transistor; wherein the second transistor and the resistor are configured to clamp a gate-source voltage of the first transistor to a value in dependence on the bias voltage; wherein the second circuit is configured to: operate in a power-saving mode in which current is blocked on the current path when the voltage level presented to the input port is equal to a threshold voltage level that corresponds to the supply voltage level, and when the voltage level presented at the input port transitions away from the threshold voltage level, transition from the power-saving mode to a wake-up mode in which current is no longer blocked in the current path, and while in the wake-up mode, control one of the plurality of communication circuits by providing a wake-up signal in response to the voltage level presented at the input port and the bias voltage. a first circuit (213, 214) configured and arranged to generate a bias (VREFH) voltage by dividing a supply voltage level provided on a power rail by a battery, relative to a ground voltage level provided on a ground rail; and a second circuit, having a current path coupled between the power rail and the ground rail, the current path comprising a first transistor with a gate coupled to an input port, wherein the first transistor is configured to pass current for generating a wake-up signal in response to transitioning of a voltage level presented on the input port; the second circuit further comprising an impedance circuit (211, 212, 215) connected between the gate and the power rail and configured to present a voltage level to the gate of the first transistor, wherein the voltage level presented to the gate of the first transistor corresponds to the voltage level presented on the input port and is less than the supply voltage level; the impedance circuit comprising: a second transistor connected in series between the supply voltage and the first transistor and having a gate connected to the bias voltage; and a resistor connected in parallel across a source and a drain terminal of the second transistor; a second transistor connected in series between the supply voltage and the first transistor and having a gate connected to the bias voltage; and a resistor connected in parallel across a source and a drain terminal of the second transistor; wherein the second transistor and the resistor are configured to clamp a gate-source voltage of the first transistor to a value in dependence on the bias voltage; wherein the second circuit is configured to: operate in a power-saving mode in which current is blocked on the current path when the voltage level presented to the input port is equal to a threshold voltage level that corresponds to the supply voltage level, and when the voltage level presented at the input port transitions away from the threshold voltage level, transition from the power-saving mode to a wake-up mode in which current is no longer blocked in the current path, and while in the wake-up mode, control one of the plurality of communication circuits by providing a wake-up signal in response to the voltage level presented at the input port and the bias voltage. operate in a power-saving mode in which current is blocked on the current path when the voltage level presented to the input port is equal to a threshold voltage level that corresponds to the supply voltage level, and when the voltage level presented at the input port transitions away from the threshold voltage level, transition from the power-saving mode to a wake-up mode in which current is no longer blocked in the current path, and while in the wake-up mode, control one of the plurality of communication circuits by providing a wake-up signal in response to the voltage level presented at the input port and the bias voltage.