TLE8262-2E Datasheet, PDF (68/94 Pages) Infineon Technologies AG – Universal System Basis Chip

TLE8262-2E
Limp Home
13.3
Activation of the Limp Home Output
The reason to activate the Limp Home pins and the consequences are listed in Table 12 and Table 13.
Table 12 Limp Home, Function of the SBC Mode
SBC Mode
Limp Home Outputs
INIT Mode
OFF
Normal Mode
OFF
ON via SPI
Stop Mode
Sleep Mode
Restart Mode
Fail-Safe Mode
SW Flash Mode
Unchanged
Unchanged
Unchanged
ON
Unchanged
ON if it was ON until the successful Watchdog
setting and deactivation via SPI.
Table 13 Automatic Activation of Limp Home Output
SBC Mode
Reason
INIT Mode
Normal Mode
INIT time-out (t_INITTO)
1st Watchdog failure (config 1/2)
2nd Watchdog failure (config 3/4)
Restart Mode
Reset output permanent short circuit to V_cc1µC
Reset output permanent short circuit to GND
Any mode
V_cc1µC undervoltage time-out
If previously turned ON in SBC Normal Mode, via SPI command
V_cc1µC thermal shutdown
13.4
Release of the Limp Home Output
When Limp Home is activated via SPI command, then it is released via SPI command. This is useful for diagnosis
purpose for example.
Otherwise, the Limp Home outputs are released only in SBC Normal Mode with the following conditions: After the
device has been set to SBC Restart Mode, automatically entering SBC Normal Mode, a successful Watchdog
trigger must be sent via SPI. At this point, the Limp Home outputs remain active. Then the microcontroller needs
to send by SPI command the deactivation of the Limp Home.
13.5
V_cc1µC undervoltage time-out
A V_cc1µC undervoltage time-out condition is given, when
1) the V_cc1µC output voltage is below the reset threshold (V_RT1, V_RT2, V_RT3),
2) V_S is higher then the threshold (V_SthUV1, V_SthUV2, V_SthUV3) and
3) the condition is valid longer then the V_cc1µC under voltage time-out (t_Vcc1UVTO).
A V_cc1µC undervoltage time-out will sent the device into Fail-Safe Mode. Limp Home output stag will be activated
(for V_s > V_LHUV)
Figure 34 gives an example of the Limp Home output activation, due to a V_cc1µC undervoltage time-out.
Data Sheet
68
Rev. 1.0, 2009-05-26