SLLA581A April   2022  – October 2025 TCAN1462-Q1 , TCAN1463-Q1 , TCAN1472-Q1 , TCAN1473-Q1 , TCAN1476-Q1 , TCAN1575-Q1 , TCAN1576-Q1

 

  1.   1
  2.   Abstract
  3.   Trademarks
  4. 1What is SIC?
  5. 2The Limitations of Classical CAN and Regular CAN FD
  6. 3How CAN SIC Reduces Bus Ringing
  7. 4Experimental Results on TI’s TCAN1462 Device
  8. 5TI’s CAN SIC Devices
  9. 6Benefits of CAN SIC
  10. 7Revision History

1 What is SIC?

CAN signal improvement capable (CAN SIC) is an improvement added to CAN FD transceivers that enhances the maximum data-rate achievable in complex network topologies by minimizing signal ringing. CAN SIC was first standardized in the CAN in Automation™ (CiA) 601-4 signal improvement specification, as an addition to the existing International Organization for Standardization (ISO) 11898-2:2016 high-speed CAN physical layer standard.

Figure 1-1 shows a regular CAN FD transceiver where the CAN bus signal rings above 900mV (the dominant threshold of a CAN receiver) and below 500mV (the recessive threshold of a CAN receiver), resulting in receive data (RXD) glitches. Figure 1-2 shows how a CAN SIC capability transceiver attenuates bus signal ringing, resulting in the correct RXD signal.

TCAN1462X CAN Bus and RXD Waveforms Without SICFigure 1-1 CAN Bus and RXD Waveforms Without SIC
TCAN1462X CAN Bus and RXD Waveforms With SICFigure 1-2 CAN Bus and RXD Waveforms With SIC

In terms of electrical parameters, a CAN SIC transceiver has a much tighter bit-timing symmetry and loop-delay specification compared to a regular CAN FD transceiver, as shown in Table 1-1. The segregation of delays of transmit and receive paths can help system designers clearly calculate network propagation delay in the presence of other signal chain components. One thing to note is that the timing specified in CiA 601-4 (and ISO 11898-2:2024 Set C and Annex A) is data-rate agnostic and holds true for both 2Mbps and 5Mbps operation.

Table 1-1 Comparing the CiA 601-4 and ISO 11898-2 Timing Specifications
Parameter Notation CiA 601-4 Specifications ISO 11898-2:2016 Specifications
Min
[ns]		 Max
[ns]		 Min
[ns]		 Max
[ns]
Signal improvement time TX-based tSIC_TX_base N/A 530 N/A
Transmitted bit-width variation ΔtBit(Bus) –10 10 –65 for 2Mbps 30 for 2Mbps
–45 for 5Mbps 10 for 5Mbps
Received bit width ΔtBit(RxD) –30 20 –100 for 2Mbps 50 for 2Mbps
–80 for 5Mbps 20 for 5Mbps
Receiver timing symmetry ΔtREC –20 15 –65 for 2Mbps 40 for 2Mbps
–45 for 5Mbps 15 for 5Mbps
Propagation delay from transmitter data (TXD) to bus dominant tprop(TxD-busdom) N/A 80 Only loop delay, TXD to bus to RXD, is specified at 255ns max
Propagation delay from TXD to bus recessive tprop(TxD-busrec) N/A 80
Propagation delay from bus to RXD dominant tprop(busdom-RxD) N/A 110
Propagation delay from bus to RXD recessive tprop(busrec-RxD) N/A 110

In 2024, CAN SIC was integrated into the overall ISO 11898-2:2024 high-speed CAN physical layer standard, with updated CAN SIC specifications. Within ISO 11898-2:2024, there are three sets of parameters with increasing data-rate: Set A, Set B, and Set C. Set C contains the governing parameters for CAN SIC transceivers (referenced as SIC mode) and now specifies the minimum SIC on time and differential SIC impedance to address theoretical corner cases and to maintain a minimum amount of ringing suppression duration. Table 1-2 shows these updated parameters.

Table 1-2 Parameters Updated in ISO 11898-2:2024 Set C
Parameter Notation ISO 11898-2:2024 Set C specifications
Min Max
Differential internal resistance (CANH to CANL) RDIFF_act_rec 75Ω 133Ω
Start time of active signal improvement phase tact_rec_start N/A 120ns
End time of active signal improvement phase tact_rec_end 355ns N/A
Start time of passive recessive phase tpas_rec_start N/A 530ns
Derived from ISO 11898-2:2024, Annex A builds on the specifications in Set C, introducing FAST mode. This FAST mode enables CAN XL, and the updates to the timing and voltage symmetry for SIC mode transceivers enable CAN XL compatibility for SIC networks and simplify migration to faster speeds. While Annex A is backward compatible to Set C, Annex A adds forward compatibility with CAN XL. The relationship between these standards is shown in Figure 1-3.

TCAN1462X CAN SIC Standards Compatibility Figure 1-3 CAN SIC Standards Compatibility

Annex A allows not only compatibility with current CAN SIC networks, but can be used in future CAN XL networks. Figure 1-4 visualizes this.

TCAN1462X System Diagram Figure 1-4 System Diagram

All CAN SIC transceivers must meet or exceed specifications set forth in ISO 11898-2:2024 Set C, with the option to add additional requirements outlined in Annex A. An exception is CAN SIC transceivers released prior to 2024, which must be compliant to CiA 601-4, the governing standard at the time. The CAN SIC specifications within ISO 11898-2:2024 are slightly modified and have generally superseded the CiA specification for new architectures and designs.

The parameters and benefits of ISO 11898-2:2024 Annex A are shown in Table 1-3.

Table 1-3 Parameters and Benefits Included in ISO 11898-2:2024 Annex A
Parameter Notation ISO 11898-2:2024 Set C Specification ISO 11898-2:2024 Annex A Specification Benefit
Differential load range RL 50-65Ω 45-65Ω A widened load range allows different cable types to be used in the network.
Differential voltage on differential load, minimum VOD_MIN 1.4V 1.5V A wider, stronger signal, that is less susceptible to dissipation.
Wake filter time tWK_FILTER 0.5 to 1.8µs 0.5 to 0.95µs A tightened wake filter-time allows for arbitration rates of 1Mbps, while still tolerant to differential noise and glitches of ≅0.5µs.
Driver symmetry Vsymmetry ±10% ±5% Tighter results in lower emissions.
Wake-up pattern N/A D-R-D D-R-D-R More resilient to false wake-up events.