OPTIREG™ SBC TLE9274QXV33
High-speed CAN transceiver
CAN FD has to be supported by both physical layer and the CAN controller. If the CAN controller cannot
support CAN FD, then the respective CAN node must at least tolerate CAN FD communication. This CAN FD
tolerant mode is implemented in the physical layer.
8.2.1
CAN OFF mode
The CAN OFF mode is the default mode after the SBC has powered up. It is available in all SBC modes and is
used to completely stop CAN activities or when CAN communication is not needed. In CAN OFF mode, a wake-
up event on the bus will be ignored.
8.2.2
CAN Normal mode
The CAN transceiver is enabled via SPI. CAN Normal mode is designed for normal data transmission/reception
within the HS CAN network. This mode is available in SBC Normal mode.
Transmission
The signal from the microcontroller is applied to the TXDCAN input of the SBC. The bus driver switches the
CANH/L output stages to transfer this input signal to the CAN bus lines.
Enabling sequence
The CAN transceiver requires an enabling time tCAN,EN before a message can be sent on the bus. This means
that the TXDCAN signal can only be pulled LOW after the enabling time. If this is not ensured, then the TXDCAN
needs to be set back to HIGH (= recessive) until the enabling time is over. Only the next dominant bit will be
transmitted on the bus. Figure 20 shows different scenarios and explanations for CAN enabling.
V
TXDCAN
t
CAN
Mode
t CAN,EN
t CAN,EN
t CAN,EN
CAN
NORM AL
CAN
OFF
t
t
V
CANDIFF
Dom inant
Recessive
recessive
TXDCAN
level required
recessive TXDCAN
level required before
start of transmission
Correct sequence,
Bus is enabled after tCAN,
tCAN, not ensured, no
transmission on bus
tCAN, not ensured,
no transmission on bus
EN
EN
EN
Figure 20 CAN transceiver enabling sequence
Reduced electromagnetic emission
To reduce electromagnetic emissions (EME), the bus driver controls CANH/L slopes symmetrically.
Reception
Analog CAN bus signals are converted into digital signals at RXDCAN via the differential input receiver.
Datasheet
49
Rev.2.0
2022-05-06
INFINEON [ Infineon ]
