TLE7259-2GU Datasheet, PDF (15/31 Pages) Infineon Technologies AG – LIN Transceiver

TLE7259-2GU
Functional Description
4.9
TxD Time Out function
If the TxD signal is dominant for a time t > t_timeout the TxD time-out function deactivates the transmission of the LIN
signal to the bus and disables the output stage. This is realized to prevent the bus from being blocked by a
permanent “Low” signal on the TxD pin, caused by an error on the external microcontroller (see Figure 10).
The transmission is released again, after a rising edge at the pin TxD has been detected.
TxD Time-Out due to
microcontroller error
Normal Communication
t_timeout
TxD
Recovery of the
microcontroller error
t_torec
Release after TxD
Time-out
Normal Communication
t
BUS
t
Figure 10 TxD Time-Out function
4.10
Over Temperature protection
The TLE7259-2GU has an integrated over temperature sensor to protect the device against thermal overstress on
the output stage. In case of an over temperature event, the temperature sensor will disable the output stage (see
Figure 1). An over temperature event will not cause any mode change nor will it be signaled by either the RxD pin
or the TxD pin. When the junction temperature falls below the thermal shut down level T_J < T_jSD, the output stage
is re-enabled and data communication can start again on the LIN bus. A 10°C hysteresis avoids toggling during
the temperature shut down.
4.11
3.3 V and 5 V Logic Capability
The TLE7259-2GU can be used for 3.3 V and 5 V microcontrollers. The inputs and the outputs are capable to
operate with both voltage levels. The RxD output must have an external pull-up resistor to the microcontroller
supply to define the output voltage level.
4.12
BUS Short to GND Feature
The TLE7259-2GU has a feature implemented to protect the battery from running out of charge in case the LIN
bus is shorted to GND.
In this failure case a normal master termination, a 1 kΩ resistor and diode between the LIN bus and the power
supply V_S, would cause a constantly drawn current even in Sleep mode. The resulting resistance of this short to
GND is in the range of1 kΩ. To avoid this current during a generator off state, like in a parked car, the TLE7259-
2GU has a bus short to GND feature implemented, which is activated in Sleep mode.
Data Sheet
15
Rev. 1.1, 2008-07-14