PXS30 Datasheet, PDF (109/139 Pages) Freescale Semiconductor, Inc – PXS30 Microcontroller

Electrical characteristics
3.21.4.3 external Reset via RESET
Figure 29 shows the voltage thresholds that determine the start of the reset sequences initiated by the
assertion of RESET as specified in Table 59.
V
RESET_SUP
0.65 × VDD_HV_IO
0.352 × VDD_HV_IO
T_{Reset, max} starts here
t
T_{Reset, min} starts here
Figure 29. Reset sequence start via RESET assertion
3.21.5 External watchdog window
If the application design requires the use of an external watchdog the data provided in Section 3.21, Reset
sequence can be used to determine the correct positioning of the trigger window for the external watchdog.
Figure 30 shows the relationships between the minimum and the maximum duration of a given reset
sequence and the position of an external watchdog trigger window.
Watchdog needs to be triggered within this window
T_{WDStart, min}
External Watchdog window closed
External Watchdog window open
T_{WDStart, max}
External Watchdog window closed
External Watchdog window open
T_{Reset, min}
Basic Application Init
Application Running
Watchdog Trigger
T_{Reset, max}
Basic Application Init
Application Running
Earliest
Application
Start
Latest
Application
Start
Application time required
to prepare watchdog trigger
Internal Reset Sequence
Start condition (signal or voltage rail)
Figure 30. Reset sequence—external watchdog trigger window position
PXS30 Microcontroller Data Sheet, Rev. 1
Freescale Semiconductor
Preliminary—Subject to Change Without Notice
109