Datasheet
LT3689/LT3689-5
26
3689fe
For more information www.linear.com/LT3689
APPLICATIONS INFORMATION
FB
0.72V
0.2V
0.2V
CPOR
CWTD
RST
WDO
RST COUNTER
WDT COUNTER
1 2
t
RST
3 4
1 2 30 31 32
3689 F13a
t
WDU
WATCH DOG INPUT MUST
TRANSITION LOW AT LEAST ONCE
IN THIS PERIOD
WATCH DOG INPUT
IS IGNORED
• • •
(13a) W/T = Low. The First Valid Negative Edge on WDI Must Occur Before the Watchdog Timer Expires
(13b) W/T = Low. Subsequent Negative Edges Must Occur Within a Fixed Time Window
(13c) W/T = Low. Restart Sequence After a Timing Fault
Figure 13. W/T = Low. Time Charts for the Power-On-Reset and Watchdog Timer in Window Mode
0.2V
WDI
CWDT
WDO
t
WDU
t
WDL
32
3689 F13b
313021
WATCH DOG INPUT
MUST TRANSITION LOW
AT LEAST ONCE IN
THIS PERIOD
• • •
0.2V
0.2V
CPOR
CWTD
WDO
RST COUNTER
WDT COUNTER
1 2 3 4
1 2 30 31 32
3689 F13c
t
RST
t
WDU
WATCH DOG INPUT MUST
TRANSITION LOW AT LEAST ONCE
IN THIS PERIOD
WATCH DOG INPUT
IS IGNORED
• • •