NXP's CAN TRANSCEIVER with Signal Improvement (SIC) | NEXTY Electronics, a trading company for electronic components and semiconductors

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CAN FD communication, which is currently the mainstream in-vehicle network, is a communication specification that extends the conventional CAN communication.
CAN FD communication enables the transmission and reception of large amounts of data at high speeds compared to conventional CAN communication, but this can cause signal ringing on the bus communication line, which can lead to communication malfunctions.

The solution to this problem is SIC (Signal Improvement Capability), which is defined in CiA601-4.
→ CiA601-4 has been unified with the release of the new ISO11898-2:2024 standard and is currently in use.

This page explains NXP's CAN TRANSCEIVER products equipped with signal improvement function (SIC), which improves the ringing that occurs when CAN is communicated at high speeds, enabling stable high-speed communication.

CAN FD Trade-Offs (Topology vs. Data Rate)

CAN networks are cost-effective, robust, scalable, easy to implement and capable of supporting complex topologies throughout the vehicle.
However, as new features are added to cars, the need for more data exchange exceeds the limits of CAN networking systems. CAN FD communication was born to address this situation, and is a technology that supports higher bandwidth than traditional CAN communication, increasing data rates from 500 Kbps to a maximum of 5 Mbps.

CAN FD uses a bus-type network topology (wiring structure) and can configure a network by connecting each node (ECU) to the communication line, which has the advantage of making the network simple and easy to design.

- Linear method
To achieve high-speed communication on a CAN bus with stubs (branches), one method is to connect using a linear topology (daisy chain), but there are concerns about increased cost and weight due to the increased harnesses.

- Multi-stub method
A multi-stub connection with multiple branches can reduce the amount of wiring required, but it can cause interference from signal reflections known as "signal ringing," which can degrade the signal quality of the CAN bus.

The following diagram shows an image of signal ringing.

In CAN FD, the 1-bit length is short, which means that the time until the sample point is reduced, and the ringing convergence time, which was not an issue with conventional CAN communication, becomes an issue.
This signal ringing effectively limits CAN FD communication to 2Mbps in many networks and restricts its use to more linear topologies.

As a result, wiring harnesses must avoid branching with long CABLES, which increases the complexity of routing the harness throughout the vehicle, resulting in increased cost and weight.

Details of SIC technology

Here we explain how NXP's SIC CAN TRANSCEIVER suppresses signal ringing.

SIC signal quality improvement functions include those that improve on the transmitting side (TX method) and those that improve on the receiving side (RX method), and NXP transceivers improve on the transmitting side. This is because the transmitting side has a standard, the TXD signal from the microcontroller, and it is thought to be superior to performing signal processing on the signal (which may include noise, etc.) transmitted over the bus. The old CiA standard included both the TX method and the RX method, but the latest standard, ISO11898-2:2024, only includes the TX method.

Active low-impedance drive of recessive edges by TXD input signal

The SIC does not immediately switch the impedance from low to high after the dominant-recessive edge, but instead maintains an intermediate impedance range (75-125 ohms). Also, the maximum delay measured from the TXD recessive is 530 nSec.

In this way, NXP's SIC technology actively improves the CAN signal, eliminating signal integrity issues caused by ringing.

SIC waveform observation

I would like to confirm the actual effect of SIC using a system demo board equipped with multiple NXP CAN TRANSCEIVER.
This time, we used the TJA1043 (without SIC) and the TJA1465A (with SIC and partial networking) to observe the bus recessive waveforms output by each. The communication speed during waveform observation was 2Mbps.

Without SIC, large ringing occurs on the bus line, exceeding the recessive confirmation level of 0.5V.

Next, we stopped the output of the TJA1043 and similarly observed the bus waveform output by the TJA1465A.
The SIC effect keeps the ringing level below 0.5V, so there is no chance of it being mistaken for a dominant.

TJA146x Product Overview

This is a product overview of NXP's SIC CAN TRANSCEIVER TJA146x.

CAN FD SIC products are pin-compatible and can be directly substituted for standard 8-pin and 14-pin CAN TRANSCEIVER.
Compatible with ISO11898-2:2016 and SAE J2284-x (WUP filter twake = 0.5μs to 1.8μs)
No software changes are required (SW driver compatibility from TJA1043 to TJA1463)
AEC-Q100 Grade-0 compliant product (TJR146x)

Summary

So far, we have explained NXP's in-vehicle network product, CAN TRANSCEIVER with signal improvement function (SIC).
NXP's wide-ranging lineup of in-vehicle network products meets a variety of customer requirements, so if you're interested, please Inquiry Nexty Electronics.