TCAN1042-Q1 Datasheet, PDF (15/32 Pages) Texas Instruments – Automotive Fault Protected CAN Tranceiver

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TCAN1042-Q1, TCAN1042V-Q1, TCAN1042H-Q1
TCAN1042HV-Q1, TCAN1042G-Q1, TCAN1042GV-Q1
TCAN1042HG-Q1, TCAN1042HGV-Q1
SLLSES9 – FEBRUARY 2016
9.3 Feature Description
9.3.1 TXD Dominant Timeout (DTO)
During normal mode (the only mode where the CAN driver is active), the TXD DTO circuit prevents the
transceiver from blocking network communication in the event of a hardware or software failure where TXD is
held dominant longer than the timeout period t_{TXD_DTO}. The DTO circuit timer starts on a falling edge on TXD.
The DTO circuit disables the CAN bus driver if no rising edge is seen before the timeout period expires. This
frees the bus for communication between other nodes on the network. The CAN driver is re-activated when a
recessive signal is seen on the TXD terminal, thus clearing the TXD DTO condition. The receiver and RXD
terminal still reflect activity on the CAN bus, and the bus terminals are biased to the recessive level during a TXD
dominant timeout.
Figure 12. Example Timing Diagram for TXD DTO
NOTE
The minimum dominant TXD time allowed by the TXD DTO circuit limits the minimum
possible transmitted data rate of the device. The CAN protocol allows a maximum of
eleven successive dominant bits (on TXD) for the worst case, where five successive
dominant bits are followed immediately by an error frame. This, along with the t_{TXD_DTO}
minimum, limits the minimum data rate. Calculate the minimum transmitted data rate by:
Minimum Data Rate = 11 / t_{TXD_DTO}.
9.3.2 Thermal Shutdown
If the junction temperature of the device exceeds the thermal shut down threshold, the device turns off the CAN
driver circuits thus blocking the TXD to bus transmission path. The shutdown condition is cleared when the
junction temperature drops below the thermal shutdown temperature of the device.
NOTE
During thermal shutdown the CAN bus drivers turn off; thus no transmission is possible
from TXD to the bus. The CAN bus terminals are biased to the recessive level during a
thermal shutdown, and the receiver to RXD path remains operational.
Copyright © 2016, Texas Instruments Incorporated
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Product Folder Links: TCAN1042-Q1 TCAN1042V-Q1 TCAN1042H-Q1 TCAN1042HV-Q1 TCAN1042G-Q1
TCAN1042GV-Q1 TCAN1042HG-Q1 TCAN1042HGV-Q1