5.10.2 LIN Standby Mode

The LIN transceiver automatically switches to the LIN Standby mode after system power-up. In this mode, LIN communication is disabled. The internal strong pull-up resistor between the LIN pin and VS pin is disabled to minimize the current consumption in case the LIN pin is short-circuited to GND. Only a weak pull-up current (typically 10 μA) between the LIN pin and the VS pin is present.

Depending on the setting of the LINWUE bit (LIN bus wake-up event detection enable, see WUCR Register), the LIN bus wake-up can be activated or deactivated. If the bit is set to ‘1’, a LIN bus voltage below the pre-wake detection LIN (VLINH) activates a strong pull-up current between VS and LIN to stabilize the recessive output voltage at the LIN pin. At the same time, an internal LIN receiver is activated and the wake-up detection timer is started. If a valid LIN bus wake-up is detected, the register bit LINWU will be set to ‘1’. The microcontroller will be notified via the NIRQ pin. The strong pull-up current will be switched off again when the LIN transceiver is in LIN Standby mode and the bit LINWU is reset by the microcontroller. LIN wake-up is disabled during a LIN transceiver overtemperature shutdown.

As shown in Figure 5-12, the LIN transceiver will enter LIN Standby mode in the following situations:

  1. From LIN Unpowered mode after device Power-on Reset.
  2. From LIN Normal mode when VS undervoltage has been detected OR the device has been switched to Deep Sleep/Sleep/Standby/MCU Reset mode OR LIN transceiver overtemperature shutdown has been detected OR LOPM is set to Standby mode.