Method, system and apparatus for suppressing controller area network bus ringing
AssigneeMicrochip Technology Incorporated
InventorJiong Ou
Life of this patent
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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 RON regulated transistor pair together with a gate control related circuit. Where the total RON is equal to the CAN bus characteristic impedance.
Claims24
A method for reducing ringing on a controller area network (CAN) bus, said method comprising the steps of:
- providing a CAN transceiver having a CAN bus driver coupled to a CAN bus, and
- matching impedance of the CAN bus with an impedance matching unit, wherein the impedance matching unit comprises an operational transconductance amplifier (OTA) and wherein the OTA comprises differential inputs coupled to the CAN bus and differential outputs coupled to the CAN bus.
A method for reducing ringing on a controller area network (CAN) bus, said method comprising the steps of:
- providing a CAN transceiver having a CAN bus driver coupled to a CAN bus, and
- matching impedance of the CAN bus with an impedance matching unit, wherein the impedance matching unit comprises a back-to-back connected Rory regulated transistor pair and a gate control circuit.
A method for reducing ringing on a controller area network (CAN) bus, said method comprising the steps of:
- providing a CAN transceiver having a CAN bus driver coupled to a CAN bus, wherein the CAN bus driver comprises slew rate control, and
- matching impedance of the CAN bus with an impedance matching unit, and further comprising the step of controlling CAN bus driver slew rate within said CAN bus driver so as to reduce high frequency signals on the CAN bus.
A system for reducing ringing on a controller area network (CAN) bus, said system comprising:
- a CAN SIC (Signal Improvement Capability) transceiver having a CAN bus driver coupled to a CAN bus, and
- an impedance matching unit selectively coupled to the CAN bus, wherein the impedance matching unit comprises an operational transconductance amplifier (OTA) comprising differential inputs coupled to the CAN bus and differential outputs coupled to the CAN bus.
A system for reducing ringing on a controller area network (CAN) bus, said system comprising:
- a CAN SIC (Signal Improvement Capability) transceiver having a CAN bus driver coupled to a CAN bus, and
- an impedance matching unit selectively coupled to the CAN bus, and
- a slew rate circuit for controlling the CAN bus driver slew rate, whereby high frequency signals on the CAN bus are reduced.
A system for reducing ringing on a controller area network (CAN) bus, said system comprising:
- a CAN SIC (Signal Improvement Capability) transceiver having a CAN bus driver coupled to a CAN bus, and
- an impedance matching unit selectively coupled to the CAN bus, wherein the impedance matching unit comprises a back-to-back connected Rory regulated transistor pair and a gate control circuit.
An apparatus for reducing ringing on a controller area network (CAN) bus, comprising:
- a CAN bus driver for driving a CAN bus,
- an impedance matching unit for selectively coupling to the CAN bus, where the impedance matching unit comprises an operational transconductance amplifier (OTA), and
- a slew rate circuit for controlling CAN bus driver slew rate.
Dependencies are inferred from the claim text.