7.3.2 Implemented Window-Watchdog Settings

The watchdog window can be set up in two different ways. The first way is to use the implemented timing, which

is a default setting. The other way is to activate the default settings by wiring the WDT and WDR pin to VDD or

GND. Four different timings available with these settings which are listed in Table 7-1.

Table 7-1. Window-Watchdog Configuration Settings

SELECTED OPERATION MODE

twindow

tboundary

WDT = 0 V

WDR = 0 V

Max = 0.3 s

Max = 9.46 ms

Typ = 0.25 s

Typ = 7.86 ms

Min = 0.2 s

Min = 6.27 ms

WDR = VDD

Max = 0.3 s

Max = 2.43 ms

Typ = 0.25 s

Typ = 2 ms

Min = 0.2 s

Min = 1.58 ms

WDT = VDD

WDR = 0 V

Max = 3 s

Max = 93.8 ms

Typ = 2.5 s

Typ = 78.2 ms

Min = 2 s

Min = 62.5 ms

WDR = VDD

Max = 3 s

Max = 23.5 ms

Typ = 2.5 s

Typ = 19.6 ms

Min = 2 s

Min = 15.6 ms

See Figure 7-2 to visualize the values named in the table. The upper boundary of the window frame is defined

by twindow and the lower boundary of the window frame is defined by tboundary. Table 7-1 describes the upper and

lower boundary settings. The device must detect a rising edge at the WDI pin between tboundary,max and twindow,min

to prevent asserting a reset. The values in Table 7-1 are typical and worst case conditions and are valid over the

whole temperature range of –40°C to +125°C.

The shaded areas shown in Figure 7-2 are cases where undefined operation may happen. This device may

not detect a violation if a WDI pulse occurs within these three shaded areas. The first shaded area addresses

the situation of two consecutive rising edges occur within a quick amount of time. The typical time between

rising edges should be more than 500 µs. The second and third shaded areas are defined by the min and

max variance of the lower boundary (tboundary) and upper boundary (twindow). Set the WDI rising edge within the

tboundary,max and twindow,min for correct operation.

Window Frame to Reset the WDI

Detection of

Rising Edge

WDI

twindow,min

twindow,typ

twindow,max

boundary,min

t

tboundary,max

tboundary,typ

t

Figure 7-2. Upper and Lower Boundary Visualization

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TPS3813K33-Q1, TPS3813I50-Q1

SPRS288H – MAY 2008 – REVISED OCTOBER 2021

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