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9145D–AUTO–05/10

ATA5021

3.6

Microcontroller in Sleep Mode

3.6.1

Monitoring with the “Long” Trigger Window

The long watchdog mode allows cyclical wake-up of the microcontroller during sleep mode. As

in short watchdog mode, there is a disable time, t

nal is accepted. The watchdog can be switched from the short trigger window to the long trigger

window with a “high” potential at the mode pin (pin 3). In contrast to the short watchdog mode,

the time periods are now much longer and the enable output remains inactive so that other com-

ponents can be switched off to effect a further decrease in current consumption. As soon as a

wake-up signal at the wake-up input (pins 1) is detected, the long watchdog mode ends, a reset

pulse wakes-up the sleeping microcontroller and the normal monitoring cycle starts with the

mode switch-over time.

Figure 3-4 shows the switch-over from the short to the long watchdog mode. The wake-up signal

during the enable time, t

The watchdog can be switched back from the long to the short watchdog mode with a low poten-

tial at the mode pin (pin 3).

Figure 3-4.

Pulse Diagram of the Long Watchdog Time

3.7

Reset-Out, Pin 5

The Reset-out pin functionality is guaranteed for supply voltage down to 1V. In case of a voltage

drop, the microcontroller gets a reset up to that value.

Reset out

Wake-up

Mode

Trigger

Enable

Pin 4

Pin 2

Pin 3

Pin 1

Pin 5