TLE7259G Datasheet, PDF (7/23 Pages) Infineon Technologies AG – LIN Transceiver

TLE 7259 G
Normal Mode
The TLE 7259 G is entering the normal mode after the µC is setting EN = high (see
Figure 3). In this mode it is possible to transmit and receive messages on the bus.
Sleep Mode
In order to reduce the current consumption the TLE 7259 G offers a sleep operation
mode. This mode is selected by switching the enable input EN low from the normal mode
(see Figure 3). In the sleep mode, a voltage regulator will be switched off via the INH
output in order to minimize the current consumption of the whole application. A wake-up
caused by a message on the communication bus (for t > t_WK,bus) or the WK pin (for
t > t_WK), automatically enables the voltage regulator by switching the INH output high.
In parallel the wake-up is indicated by setting the RxD output LOW. The TxD input
automatically is set to LOW if the source of the wake-up was the WK-pin, otherwise TxD
is HIGH. So, the RxD pin can be used as a flag to indicate a wake-up from sleep mode
and the TxD flag can be used as an indicator for the wake-up source (see Figure 3).
When entering the normal mode these wake-up flags are reset and the RxD output and
TxD input is released to receive/transmit the bus data.
In case the voltage regulator control input is not connected to INH output or the
microcontroller is active respectively, the TLE 7259 G can be set in normal operation
mode without a wake-up via the communication bus.
Application Information
Master Termination
To achieve the required timings for the dominant to recessive transition of the bus signal
an additional external termination resistor of 1 kΩ is mandatory. It is recommended to
place this resistor at the master node. To avoid reverse currents from the bus line into
the battery supply line it is recommended to place a diode in series to the external pull-
up. For small systems (low bus capacitance) the EMC performance of the system is
supported by an additional capacitor of at least 1 nF in the master node (see Figure 6
and Figure 7, application circuit).
BUS short to GND Feature
The TLE 7259 G has a feature implemented to protect the battery from running out of
charge in the case of BUS short to GND.
In this failure case a normal master termination connection like described above, 1 kΩ
resistor and diode between bus and V_S, would cause a constantly drawn current even in
sleep mode. The resulting resistance of this short to GND is lower than 1 kΩ. To avoid
this current during a generator off state, like a parked car, the sleep mode has a bus short
to GND feature implemented in the TLE 7259 G. This feature is only applicable, if the
Preliminary Data Sheet
7
Rev. 1.3, 2004-12-13