7.3.2.1.3 SET0 and SET1 During Normal Watchdog Operation

The SET0 and SET1 pins can be used to control the window watchdog ratio of the lower boundary to the upper

boundary. There are four possible modes for the watchdog (see Table 8-5 ): disabled, 1:8 ratio, 3:4 ratio, and

1:2 ratio. If SET0 = 1 and SET1 = 0, then the watchdog is disabled. When the watchdog is disabled WDO does

not assert, and the TPS3430 ignores all inputs to WDI. The SET0 and SET1 pins can be changed when the

device is operational, but cannot be changed at the same time. If these pins are changed when the device is

operational, then there must be a 500-µs (tSET) delay between switching the two pins. If the SET0 and SET1 are

used to change the reset timing, then a reset event must occur before the new timing condition is latched. This

reset can be triggered by bringing VDD below VUVLO. Figure 7-4 shows how the SET0 and SET1 pins do not

change the watchdog timing option until a reset event has occurred.

SET0

SET1

VDD 1 = VDD 2

RATIO

1:8

1:2

t

SET

Figure 7-4. Changing SET0 and SET1 Pins

TPS3430

SBVS366A – JULY 2018 – REVISED OCTOBER 2021

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