Data Sheet

14

Rev. 1.0

2017-08-09

HS CAN Transceiver

High Speed CAN Transceiver

Fail safe functions

7

Fail safe functions

7.1

Short circuit protection

The CANH and CANL bus pins are proven to cope with a short circuit fault against GND and against the supply

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

a continuous short on the CANH or CANL, the internal overtemperature protection switches off the bus

transmitter.

7.2

Unconnected logic pins

logical pins are open, the TLE9250 enters into the Power-save mode by default.

7.3

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 might have its root cause in a locked-

up microcontroller or in a short circuit on the printed circuit board, for example.

feature and the TLE9250 disables the transmitter (see Figure 8). The receiver is still active and the data on the

bus continues to be monitored by the RxD output pin.

Figure 8

TxD time-out function

Figure 8 illustrates how the transmitter is deactivated and activated again. A permanent “low” signal on the

TxD input pin activates the TxD time-out function and deactivates the transmitter. To release the transmitter

after a TxD time-out event, the TLE9250 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