MPC5643L datasheet(108/136 Pages) FREESCALE

108 / 136 page

MPC5643L Microcontroller Data Sheet, Rev. 8.1

Electrical characteristics

Freescale Semiconductor

108

Figure 18. Reset sequence start via RESET assertion

3.19.5

External watchdog window

If the application design requires the use of an external watchdog the data provided in Section 3.19, Reset sequence can be used

to determine the correct positioning of the trigger window for the external watchdog. Figure 19 shows the relationships between

the minimum and the maximum duration of a given reset sequence and the position of an external watchdog trigger window.

Figure 19. Reset sequence - External watchdog trigger window position

3.20

AC timing characteristics

AC Test Timing Conditions: Unless otherwise noted, all test conditions are as follows:

• TJ = –40 to 150 C

• Supply voltages as specified in Table 9

TReset, max starts here

TReset, min starts here

RESET_B

0.65 * VDD_HV_IO

0.35 * VDD_HV_IO

RESET

External Watchdog Window Closed

Earliest

Application

Start

Latest

Application

Start

Internal Reset Sequence

Start condition (signal or voltage rail)

External Watchdog Window Open

TReset, min

TReset, max

TWDStart, min

TWDStart, max

External Watchdog Window Closed

External Watchdog Window Open

Basic Application Init

Application time required to

prepare watchdog trigger

Watchdog needs to be triggered within this window

Watchdog trigger

Application Running

MPC5643L 数据表(PDF) 108 Page - Freescale Semiconductor, Inc

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