SPRS288H May 2008 – October 2021
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.
|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.