User Manual
49
Rev. 1.1
2019-03-18
TLE984xQX
Microcontroller with LIN and Power Switches for Automotive Applications
Power Management Unit (PMU)
PCU supervision function will set the device into Sleep Mode. In this case the device is still wakeable by LIN
and MON input.
After a wake-up, if the PMU can be successfully restarted and code execution will be possible, the user is able
to determine the occurred failure scenario by checking the corresponding
SUPP_TMOUT
is set.
If there is a short circuit at the VDDC/VDDP voltage regulator during startup, the reset of the embedded MCU
is set and the system goes to startup mode. The error counter “error_supp” is increased by one. After this the
PCU itself tries to go to Active Mode again using the power-on sequence. If the short circuit still exists then the
procedure is repeated. This procedure will run, as already described above, only 5 times. After reaching the
value 5, the PCU sends the system into Sleep Mode.
If a successful startup after wake-up from Sleep Mode is possible, the user is able to verify the failure, by
reading the
SUPP_TMOUT
flag in the
register.
6.4.1.2
Watchdog (WDT1) Fail Safe
The PCU supervises the failure information of the system watchdog (WDT1). In case the watchdog is not
serviced or serviced in a wrong way (in the following denominated as “not serviced Watchdog”) the MCU is
reset and the error counter “error_wdt” is increased by one. The PMU itself stays in the Active Mode and after
the reset the application software takes over the system control. If the software doesn’t service the system
watchdog then the described procedure starts again. After the watchdog is not serviced five times during one
Active Mode period the PMU sends the embedded system to Sleep Mode. The PMU detects the transition to
the Sleep Mode as safety fallback and the Sleep Mode can be terminated only by a LIN-wake or by a
rising/falling edge at a MON pin. The error counter is reset when the system is sent to Sleep Mode or Stop Mode
by a corresponding software command.
If the system can be successfully restarted, the cause of failure can be again checked by reading the
register. The bit
WDT1_SEQ_FAIL
signals the described failure.
6.4.1.3
Main Regulators Fail Safe
If one of the voltage regulators needs to deliver too much current, a stable operation of the supply voltage is
not given. In this case the overcurrent detection of VDDP and VDDC will ensure that the system will enter Sleep
Mode.
If the overcurrent condition is gone, a wake-up can be invoked, then the system will startup and work
properly. Afterwards the corresponding failure flags
PMU_1V5_OVL
and PMU_5V_OVL can be checked.
6.4.1.4
VDDEXT Failure
If VDDEXT is used in combination with the GPIOs as a supply e.g. for the switches, there are several error cases
possible, which are: Overtemperature, undervoltage. Those error cases may lead to the generation of false
wake-up events or to missed wake-up events. To avoid these scenarios, errors on the VDDEXT voltage
regulator would automatically revive the system from Stop Mode. The errors are signalled in the
register.
6.4.1.5
Wake-Up from Stop Mode with Reset Fail Safe