7.3.3 Window Watchdog Timer

This section provides information for the window watchdog modes of operation. A window watchdog is typically

employed in safety critical applications where a traditional watchdog timer is inadequate. In a traditional

watchdog, there is a maximum time in which a pulse must be issued to prevent the reset from occurring.

However, in a window watchdog the pulse must be issued between a maximum lower window time (tWDL(max))

and the minimum upper window time (tWDU(min)) set by the CWD pin and the SET0 and SET1 pins. Table 8-5

describes how tWDU can be used to calculate the timing of tWDL. The tWDL timing can also be changed by

adjusting the SET0 and SET1 pins. Figure 7-5 shows the valid region for a WDI pulse to be issued to prevent the

WDO from being triggered and being pulled low.

tWDL(min)

Window

Timing

WDI

tWDL(typ)

tWDL(max)

tWDU(min)

tWDU(typ)

tWDU(max)

WDO

= Tolerance Window

Early Fault

WDO

Late Fault

WDI

Valid

Window

Correct Operation

WDI

WDO

Figure 7-5. TPS3430 Window Watchdog Timing

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TPS3430

SBVS366A – JULY 2018 – REVISED OCTOBER 2021

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