SLLSFK7A March 2021 – April 2022 TLIN2021A-Q1
PRODMIX
While the LIN driver is in active mode a TXD DTO circuit prevents the local node from blocking network communication in the event of a hardware or software failure where TXD is held dominant longer than the time-out period tTXD_DTO. The TXD DTO circuit is triggered by a falling edge on TXD. If no rising edge is seen before the time-out constant of the circuit, tTXD_DTO, expires the LIN driver is disabled releasing the bus line to the recessive level. This keeps the bus free for communication between other nodes on the network. The LIN driver is re-activated on the next dominant to recessive transition on the TXD terminal, thus clearing the dominant time-out. During this fault, the transceiver remains in normal mode, the integrated LIN bus pull-up termination remains on, and the LIN receiver and RXD terminal remain active reflecting the LIN bus data.
The TXD pin has an internal pull-down to ensure the device fails to a known state if TXD is disconnected. If EN pin is high at power-up, the TLIN2021A-Q1 enters normal mode. With the internal TXD connected low, the DTO timer starts. To avoid a tTXD_DTO fault, a recessive signal should be put onto the TXD pin before the tTXD_DTO timer expires, or the device should be into sleep mode by connecting EN pin low.