A device comprising: a transmission circuit configured and arranged to transmit data in accordance with a signal bus protocol that uses passive bias to set a signal bus to a recessive value in the absence of an actively-driven signal value and including: a first driver (108, 110) circuit configured and arranged to actively drive the signal bus to a dominant value that is different from the recessive value, and a second driver circuit (106, 112) configured and arranged to actively drive the signal bus to the recessive value; and characterized by a control circuit configured and arranged to: disable the second driver circuit (106,112) in response to the device operating in a first data transmission mode corresponding an arbitration mode for a controller area network protocol wherein the device is configured and arranged to perform bus arbitration by monitoring the signal bus to detect that another device has driven a dominant value on the signal bus; and enable the second driver circuit (106, 112) in response to the device entering a second transmission mode corresponding to a high speed mode for the controller area network protocol wherein the device is configured and arranged to actively drive the signal bus to both the recessive value and the dominant value. a transmission circuit configured and arranged to transmit data in accordance with a signal bus protocol that uses passive bias to set a signal bus to a recessive value in the absence of an actively-driven signal value and including: a first driver (108, 110) circuit configured and arranged to actively drive the signal bus to a dominant value that is different from the recessive value, and a second driver circuit (106, 112) configured and arranged to actively drive the signal bus to the recessive value; and characterized by a first driver (108, 110) circuit configured and arranged to actively drive the signal bus to a dominant value that is different from the recessive value, and a second driver circuit (106, 112) configured and arranged to actively drive the signal bus to the recessive value; and characterized by a control circuit configured and arranged to: disable the second driver circuit (106,112) in response to the device operating in a first data transmission mode corresponding an arbitration mode for a controller area network protocol wherein the device is configured and arranged to perform bus arbitration by monitoring the signal bus to detect that another device has driven a dominant value on the signal bus; and enable the second driver circuit (106, 112) in response to the device entering a second transmission mode corresponding to a high speed mode for the controller area network protocol wherein the device is configured and arranged to actively drive the signal bus to both the recessive value and the dominant value. disable the second driver circuit (106,112) in response to the device operating in a first data transmission mode corresponding an arbitration mode for a controller area network protocol wherein the device is configured and arranged to perform bus arbitration by monitoring the signal bus to detect that another device has driven a dominant value on the signal bus; and enable the second driver circuit (106, 112) in response to the device entering a second transmission mode corresponding to a high speed mode for the controller area network protocol wherein the device is configured and arranged to actively drive the signal bus to both the recessive value and the dominant value.