TLE8262-2E Datasheet, PDF (54/94 Pages) Infineon Technologies AG – Universal System Basis Chip

TLE8262-2E
Supervision Functions
11
Supervision Functions
11.1
Reset Function
11.1.1 Description
The reset output pin RO provides information to the microcontroller, for example, in the event that the output
voltage has fallen below the undervoltage threshold V_RT1/2/3. When connecting the SBC to battery voltage, the
reset signal remains LOW initially. When the output voltage V_cc1µC has reached the reset threshold V_RT1,r, the reset
output RO remains LOW for the reset delay time t_rd1. After that the RO is released to HIGH. A reset can also occur
due to faulty Watchdog refresh.See Chapter 11.2. The reset threshold as well as the reset delay time can be
adjusted via SPI. The RO pin has an integrated pull-up resistor.
11.1.2 Reset diagnosis
The RO pin is diagnosed for both short circuit to V_ccx and GND. Depending on the configuration, in case of RO
failure, the SBC goes to SBC Fail-Safe or Restart Mode and activate the Limp Home output.
In case of short circuit to GND, it is detected in any SBC mode except SBC Restart Mode. At the falling edge of
the RO, when supposed to be HIGH, the SBC enters automatically the SBC Restart Mode. If after the t_rd and RO
relaxation, the RO pin is still LOW, then the SBC detects the clamping to LOW failure. The microcontroller is in
permanent reset.
In case of short circuit to V_ccx, the SBC cannot detect the short circuit before a reset should occur. So reset
clamped is detected when the SBC goes to SBC Restart Mode or during Init Mode.
11.1.3 Reset Timing
V_CC
V_RTx
t < t_RR
undervoltage
t_RD1
t_LW
t_CW
t_OW
SPI
t_CW
t_OW
t_RDx
t
t_CW
t_LW
SPI
WD
WD
Init
Trigger
Trigger
RO
t_RR
SPI
Init
t
SBC Init
Figure 22 Reset Timing Diagram
Data Sheet
SBC Normal
54
SBC Restart
t
SBC Normal
Res_per_8264.vsd
Rev. 1.0, 2009-05-26