A Controller Area Network, CAN, transceiver comprising: two bus terminals (601, 602) for coupling said transceiver to a CAN bus; a transmitter arrangement configured to transmit signalling on the CAN bus via said bus terminals based on transmit data received at a transmit input, the transmit input comprising a terminal for coupling to a CAN controller, the transmitter arrangement comprising at least one transmitter (605, 606) configured to drive the bus to a dominant state or to a recessive state based on the transmit signal, and comprising an impedance control device connected to the two bus terminals; a signalling detector (612, 613) configured to detect signalling from the CAN controller received at the transmit input with the transmit data, the signalling detector configured to determine the length of time the transmit data comprises a logic zero state prior to a transition in the transmit data from said logic zero state to a logic one state and: based on the length of time being longer than a predetermined threshold, provide for control of an output impedance by the impedance control device in accordance with a first scheme comprising controlling the output impedance to be within a predefined range of an impedance value at the dominant state while a differential driver voltage on a CAN bus connected to the CAN transceiver decreases to a predefined voltage and then increasing the output impedance over a first predetermined time duration such that said increasing comprises two separate increases separated by a period of substantially constant output impedance over a bit time for said logic one state; and based on the length of time being shorter than said predetermined threshold, provide for one of: control of said output impedance in accordance with a second scheme different to the first scheme; and no control of the output impedance by the impedance control device. two bus terminals (601, 602) for coupling said transceiver to a CAN bus; a transmitter arrangement configured to transmit signalling on the CAN bus via said bus terminals based on transmit data received at a transmit input, the transmit input comprising a terminal for coupling to a CAN controller, the transmitter arrangement comprising at least one transmitter (605, 606) configured to drive the bus to a dominant state or to a recessive state based on the transmit signal, and comprising an impedance control device connected to the two bus terminals; a signalling detector (612, 613) configured to detect signalling from the CAN controller received at the transmit input with the transmit data, the signalling detector configured to determine the length of time the transmit data comprises a logic zero state prior to a transition in the transmit data from said logic zero state to a logic one state and: based on the length of time being longer than a predetermined threshold, provide for control of an output impedance by the impedance control device in accordance with a first scheme comprising controlling the output impedance to be within a predefined range of an impedance value at the dominant state while a differential driver voltage on a CAN bus connected to the CAN transceiver decreases to a predefined voltage and then increasing the output impedance over a first predetermined time duration such that said increasing comprises two separate increases separated by a period of substantially constant output impedance over a bit time for said logic one state; and based on the length of time being shorter than said predetermined threshold, provide for one of: control of said output impedance in accordance with a second scheme different to the first scheme; and no control of the output impedance by the impedance control device. based on the length of time being longer than a predetermined threshold, provide for control of an output impedance by the impedance control device in accordance with a first scheme comprising controlling the output impedance to be within a predefined range of an impedance value at the dominant state while a differential driver voltage on a CAN bus connected to the CAN transceiver decreases to a predefined voltage and then increasing the output impedance over a first predetermined time duration such that said increasing comprises two separate increases separated by a period of substantially constant output impedance over a bit time for said logic one state; and based on the length of time being shorter than said predetermined threshold, provide for one of: control of said output impedance in accordance with a second scheme different to the first scheme; and no control of the output impedance by the impedance control device.