Data Sheet

10

Rev. 1.11

2016-12-29

TLE8250GVIO

High Speed CAN-Transceiver

Fail Safe Functions

5

Fail Safe Functions

5.1

Short circuit protection

The CANH and CANL bus outputs are short-circuit-proof, either against GND or a positive supply voltage. A

current limiting circuit protects the transceiver against damages. If the device is heating up due to a continuos

short on CANH or CANL, the internal over-temperature protection switches off the bus transmitter.

5.2

Open Logic Pins

are open or floating, the TLE8250GVIO enters into the Stand-By mode per default. In Stand-By mode the

output driver stage of the TLE8250GVIO is disabled, the bus biasing is shut off and the HS CAN TLE8250GVIO

transceiver will not influence the data on the CAN bus.

5.3

TxD Time-Out function

The TxD Time-out feature protects the CAN bus against permanent blocking in case the logical signal on the

TxD pin is continuously “Low”. A continuous “Low” signal on the TxD pin can have it’s root cause in a locked-

up microcontroller or a short on the printed circuit board for example. In Normal Operation mode, a logical

disables the output driver stage (see Figure 5). The receive unit is still active and the data on the bus are still

monitored by the RxD output pin.

Figure 5

TxD Time-Out function

Figure 5 shows the way how the transmission stage is deactivated and activated again. A permanent “Low”

signal on the TxD input pin activates the TxD time-out function and deactivates the transmitter output stage.

To release the transmitter output stage after a TxD time-out event the TLE8250GVIO requires a signal change

on the TxD input pin from logical “Low” to logical “High”.

TxD

t

t

CANH

CANL

RxD

t

TxD Time - Out

TxD Time – Out released