MPC5746R Hardware Design Guide, Rev. 1
Example Communication Peripheral connections
NXP Semiconductors44
10.3 CAN interface circuitry
Controller Area Network (CAN) is commonly used in almost all automotive applications to allow
communication between various microchips in the car.
MPC5746R incorporates 4 CAN modules on-chip. A separate CAN transceiver is required for each CAN
module, although some CAN transceivers may have more than one transceiver on a single chip. It is
possible to connect two CAN modules to a single transceiver if the transmit pins are put into open-collector
mode with an external pull-up resistor. However, the value of this resistor may limit the maximum speed
of the CAN module if not sized properly for the speed. The MPC5746R CAN modules conform to CAN
protocol specification version 2.0B protocol. The transceivers shown in this application note comply with
ISO 11898 physical layer standard.
Typically, CAN is used at either a low speed (5 kbit/s to 125 kbit/s) or a high speed (250 kbit/s to 1 Mbit/s).
Powertrain applications typically use a high speed (HS) CAN interface to communicate between the
engine control unit and the transmission control unit. Body and chassis applications typically use a low
speed (LS) CAN interface. In the dashboard of a vehicle, there is typically a gateway device that interfaces
between HS and LS CAN networks.
NXP includes high speed CAN physical interfaces in some System Basis Chip (SBC) devices that can be
used to provide the CAN physical interface and the device power supply. Refer to the MC33908 Data
Sheet for more information. Some of these devices include a LIN physical interface. Other popular CAN
transceivers include the NXP devices shown in the following table. Example TJA1050 HS and TJA1054
LS circuits are shown in this application note.
10.3.1 High-speed CAN TJA1050 interface
The figure below shows the typical connections for the physical interface between the MCU and the CAN
bus for high-speed applications using the NXP TJA1050 HS CAN transceiver.
Table 23. NXP CAN Transceivers
Device
TJA1050 TJA1054 TJA1040 TJA1041
Bitrate (kbit/s) 1000 125 1000 1000
Modes of Operation Normal, Listen-only Normal, Standby, Sleep Normal, Standby
Normal, Listen-only,
Standby, Sleep
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