Controller Area Network ICs to Implement ISO 11898 Communications

A controller area network (CAN) is a digital bus protocol defined by ISO 11898. The standard comprises several sections, defining both the physical and data link layers for transmission communication. The protocol was developed and is used primarily in automotive applications to link sensors, actuators, and other control devices within a contained environment. A contained environment is necessary as transmission speeds are limited by cable length.

Multiple devices may be attached to the network which provides for multiple masters. The standard defines arbitration protocols and electrical characteristics of the physical layer including voltage, current, and a number of conductors necessary for transmission. Mechanical standards are less clear although existing networks have adopted 9-pin D-sub connectors. Conductors include positive/negative pairs for data transmission along with power and ground. The data pairs typically travel along twisted pair conductors within the cables.

A host controller connects devices via a CAN transceiver. The standard allows communication with devices powered on rails ranging between 7V and 30V, characteristics from devices commonly found in automotive systems. The transceiver level-shifts and presents signals to the host for arbitration and resolution of command priority between host processors and devices attached to the network. Although originally developed for automotive applications, the network is replacing point-to-point connections leading to CANs populating into industrial, medical, and avionic area network architectures as well.

Defining Characteristics of Controller Area Networks

Controller area networks were developed in the early 80s to connect sensors and actuators within automobiles. Transmission speeds required and designed into the standard range from 30kbs to 5Mbs. Speeds higher than this are unnecessary for communicating sensor and actuator data, so the network was able to support longer cables used within noisy automotive environments. With fewer conductors connecting multiple devices and elegant arbitration, the network supports multiple design features at low cost.

Automobile oxygen sensor communicates via CAN

CAN networks support multiple masters for communication along a two-wire data bus. Masters are located at nodes along with a CAN controller and transceiver. Although data is transmitted on a two-wire bus, the signaling system differs from differential pair types and instead uses wired-AND logic to communicate access requests. Termination resistors of 120Ω are placed at either end of transmission lines to pull one of the pair high while the other pulls low. When inactive, the pair tends to float toward a middle voltage.

CAN Controllers arbitrate device access requests and send information to the node’s master. In this way, CAN Controllers connect nodes and nodes connect embedded systems within a confined network. Connecting embedded systems allows more accessibility to users of the automobile, or other product, features. The message-based protocol used by CAN networks makes the system autonomous and able to multiplex commands on the same set of wires.

Parameters to Consider When Selecting a CAN

If you are designing with sensors and actuators within a closed network, you may want to consider employing a CAN Controller IC. This type of part is designed with pinouts to accept two-wire communications from a multiple of powered devices. The ICs incorporate transceivers to level-shift before sending for processing by the master. All are designed for compatibility with CAN bus standard ISO 11898.

TCAN4550-Q1 CAN FD Controller with Integrated Transceiver

This part is a flexible data rate controlled area network for use in automotive applications It may be used in standalone applications or it may be integrated into a larger automotive control unit using serial peripheral interface for short-distance communications.

The TCAN4550-Q1 is a CAN FD Controller with integrated CAN transceiver supporting data rates up to 5 Mbps. The device interfaces with a microprocessor using the SPI interface. The CAN FD processor meets the specifications of the ISO11898-1_2015 standard and the CAN transceiver meets the specification for High Speed CAN (Controller Area Network) Physical Layer standards: 11898-2_2016. The device can also wake up via remote wake-up using CAN bus implementing the ISO Wake Up Pattern (WUP).

Found on page 1 of TCAN4550-Q1 CAN FD Controller with Integrated Transceiver datasheet

This part is AEC Q100 qualified and able to operate over a wide range from 12V to 42V. It is applicable for body electronics and lighting, infotainment and cluster, passive safety, and industrial transportation.

MCP2561/2 High-Speed CAN Transceiver

This part supports 1Mbps along a controlled area network and is designed for use with the vehicle bus standard. It is designed to connect independent devices to a system controller.

The MCP2561/2 is a Microchip Technology Inc. second generation high-speed CAN transceiver. It serves as an interface between a CAN protocol controller and the physical two-wire CAN bus.

Found on page 7 of MCP2561/2 High-Speed CAN Transceiver datasheet

This part is qualified for use in automotive applications and is available in several package footprints including PDIP, SOIC, and DFN. It is suitable as the physical layer for compatible automotive design protocols making it a good choice for creating design flexibility.

MAX14882 5kVRMS Isolated CAN Transceiver with Integrated Transformer Driver

This part is suitable for use in automotive and industrial applications employing protocols for short-range communication over twisted pair signals. It incorporates an input transformer to allow robust protection from outside transient events.

The MAX14882 isolated high-speed CAN transceiver improves communication and safety by integrating galvanic isolation between the CAN-protocol controller-side (TDX, RXD) of the device and the physical wires of the CAN network (CANH, CANL) cable-side/bus-side of the transceiver. Isolation improves communication by breaking ground loops and reduces noise where large differences in ground potentials exist between ports. The MAX14882 provides up to 5000VRMS (60s) of galvanic isolation and continuous working voltage of up to 848VRMS, while operating at the maximum high-speed CAN data rate of 1Mbps.

Found on page 1 of MAX14882 5kVRMS Isolated CAN Transceiver with Integrated Transformer Driver datasheet

This part integrates both isolation protection along with an integrated LDO and transceiver. Exceeding ISO 11858 specification requirements allows use in building automation, industrial controls, HVAC, and switching gears along with applications in automotive for short-range communication using CAN protocol.

Whatever your need for controlled area network protocol and interfaces with your embedded controllers, we have parts for your consideration here. With a comprehensive database covering all major vendors and distributors, our parts selector can help refine your search. Once you select a part and are ready to input it into your schematic, you can use the CAD models offered on our website.

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