TLE6251-3G Datasheet, PDF (17/36 Pages) Infineon Technologies AG – High Speed CAN-Transceiver with Wake and Failure Detection

TLE6251-3G
Fail Safe Features
7
Fail Safe Features
7.1
CAN Bus Failure Detection
The High Speed CAN Transceiver TLE6251-3G is equipped with a bus failure detection unit. In Normal Operation
mode the TLE6251-3G can detect the following bus failures:
• CANH shorted to GND
• CANL shorted to GND
• CANH shorted to V_CC
• CANL shorted to V_CC
• CANH shorted to V_S
• CANL shorted to V_S
The TLE6251-3G can not detect the bus failures:
• CANH open
• CANL open
• CANH short to CANL
The TLE6251-3G detects the bus failures while sending a “Dominant” signal to the CAN bus. After sending four
“Dominant” bits to the CAN bus, a logical “Low” on the NERR pins indicates the CAN bus failure. For the failure
indication the “Dominant” bits require a minimum pulse width of 4 μs. In case the TLE6251-3G detects an CAN bus
failure, the failure is only indicated by the NERR pin, the transceiver doesn’t stop or block the communication, by
disabling the output stage for example.
CANH
CANL
Short to V_CC
t
TxD
t
RxD
t
NERR
t
Four Dominant Bits
Figure 9 CAN Bus Failure CANH short to V_CC1)
1) The communication on the CAN bus could still be possible even with a short CANH to V_CC or CANH to V_S. If the CAN bus
communication is possible or not, depends on parameters like the number of participants inside the CAN network, the
network termination, etc. This figure shows a working CAN bus communication as an example and it shall not be
considered as a liability that on HS CAN networks the CAN bus communication continues in every CAN bus failure case.
Data Sheet
17
Rev. 1.1, 2011-06-06