u5021m ATMEL Corporation, u5021m Datasheet - Page 6

• Manufacturer Part Number: u5021m
• Description: Digital Window Watchdog Timer
• Manufacturer: ATMEL Corporation

Figure 4-4.
Figure 4-5.
5. State Diagram
6
U5021M
Reset out
Mode
Trigger
Enable
Reset out
Wake-up
Mode
Trigger
Enable
V
DD
Pulse Diagram of a Correct Trigger Sequence During the Short Watchdog Time
Pulse Diagram of the Long Watchdog Time
Figure 4-5
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).
The kernel of the watchdog is a finite state machine.
possible states and transmissions. Many transmissions are controlled by an internal timer. The
numbers for the time-outs are the same as on the pulse diagrams.
shows the switch-over from the short to the long watchdog mode. The wake-up signal
t
2
t
0
5
t
, activates a reset pulse, t
1
t
4
t
2
6
.
Figure 5-1
t
t
trig
t
3
5
t
shows the state diagram with all
6
t
t
2
1
Pin 3
Pin 2
Pin 4
Pin 5
Pins 1
4756D–AUTO–11/05
Pin 6
Pin 5
Pin 3
Pin 2
Pin 4