TLE7250X Datasheet, PDF(15/34 Page) Infineon Technologies AG

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TLE7250X Datasheet, PDF (15/34 Pages) Infineon Technologies AG – High Speed CAN-Transceiver

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Fail Safe Functions

TLE7250XLE

TLE7250XSJ

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 continuous short on

the CANH or CANL, the internal overtemperature protection switches off the bus transmitter.

5.2

Unconnected Logic Pins

All logic input pins have an internal pull-up resistor to VIO or a pull-down resistor to GND. In case the VIO supply is

activated and the logical pins are open, the TLE7250X enters into the normal-operating mode by default. The TxD

input is pulled to logical âhighâ due to the internal pull-up resistor to VIO. The HS CAN transceiver TLE7250X will

not influence the data on the CAN bus as long the TxD input pin remains logical âhighâ.

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 âlowâ. A continuous âlowâ 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. In normal-operating mode, a logical

âlowâ signal on the TxD pin for the time t > tTxD enables the TxD time-out feature and the TLE7250X 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.

CANH

CANL

t > tTxD

TxD time-out

TxD timeâout released

TxD

RxD

Figure 8 TxD time-out function

Figure 8 illustrates how the transmitter is deactivated and activated again. A permanent âlowâ 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 TLE7250X requires a signal change on the TxD input pin from logical âlowâ to logical âhighâ.

Data Sheet

Rev. 1.0, 2015-08-12

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