MAX6864UK29D3S Просмотр технического описания (PDF) - Maxim Integrated
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MAX6864UK29D3S
Maxim Integrated
MAX6864UK29D3S Datasheet PDF : 17 Pages
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Nanopower µP Supervisory Circuits with
Manual Reset and Watchdog Timer
input at different points in the program, rather than
pulsing the watchdog input high-low-high or low-high-
low. This technique avoids a stuck loop, in which the
watchdog timer would continue to be reset inside the
loop, keeping the watchdog from timing out.
Figure 6 shows an example of a flow diagram where
the I/O driving the watchdog input is set high at the
beginning of the program, set low at the beginning of
every subroutine or loop, then set high again when the
program returns to the beginning. If the program
should hang in any subroutine, the problem would
quickly be corrected, since the I/O is continually set low
and the watchdog timer is allowed to time out, causing
a reset or interrupt to be issued.
START
SET WDI
HIGH
PROGRAM
CODE
SUBROUTINE OR
PROGRAM LOOP
SET WDI LOW
RETURN
Figure 6. Watchdog Flow Diagram
Table 2. Threshold Suffix Guide
SUFFIX
46
45
44
43
42
41
40
39
38
37
36
35
34
33
32
31
30
29
28
27
26
25
24
23
225
22
21
20
19
18
17
16
VCC THRESHOLD FALLING
MIN
TYP
MAX
4.509
4.625
4.741
4.388
4.500
4.613
4.266
4.375
4.484
4.193
4.300
4.408
4.095
4.200
4.305
3.998
4.100
4.203
3.900
4.000
4.100
3.802
3.900
3.998
3.705
3.800
3.895
3.608
3.700
3.793
3.510
3.600
3.690
3.413
3.500
3.588
3.315
3.400
3.485
3.218
3.300
3.383
3.120
3.200
3.280
2.998
3.075
3.152
2.925
3.000
3.075
2.852
2.925
2.998
2.730
2.800
2.870
2.633
2.700
2.768
2.559
2.625
2.691
2.438
2.500
2.563
2.340
2.400
2.460
2.255
2.313
2.371
2.180
2.235
2.290
2.133
2.188
2.243
2.048
2.100
2.153
1.950
2.000
2.050
1.853
1.900
1.948
1.755
1.800
1.845
1.623
1.665
1.707
1.536
1.575
1.614
UNITS
V
Table 3. Watchdog Timeout
SUFFIX
S
L
WATCHDOG TIMEOUT PERIOD
MIN
TYP
MAX
UNITS
1.5
3.3
7.75
s
95
209
487
______________________________________________________________________________________ 13
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