Datasheet

7Atmel ATA5021 [DATASHEET]
9145G–AUTO–09/12
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
4
, and an enable time, t
5
, in which a trigger signal 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 components 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
5
,
activates a reset pulse, t
6
.
The watchdog can be switched back from the long to the short watchdog mode with a low potential 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
t
2
t
1
t
6
t
4
t
5