Microchip Technology Incorporated
METHOD, SYSTEM AND APPARATUS FOR SUPPRESSING CONTROLLER AREA NETWORK BUS RINGING

Abstract:

CAN bus drive slew rate control is used to suppress ringing using bus impedance matching that is only activated during and shortly after the bus driver unit transitions from driving the bus "dominant" to "recessive". In one embodiment a bus impedance matching unit is a differential input and differential output operational trans-conductance amplifier (OTA). The differential OTA absorbs or provides the ringing current based on bus differential voltage. In another embodiment a bus impedance matching unit is a back-to-back connected R.sub.ON regulated transistor pair together with a gate control related circuit. Where the total R.sub.ON is equal to the CAN bus characteristic impedance.