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MB3773
OPERATION SEQUENCE
(1) When Vcc rises to about 0.8 V, RESET goes "Low" and RESET goes "High".
The pull-up current of approximately 1 A (Vcc = 0.8 V) is output from RESET.
(2) When Vcc rises to V
At this time, the output is being reset.
(3) When C
begins charging, RESET goes "High" and RESET goes "Low".
T
After T
reset of the output is released.
PR
Reset hold time: T
After releasing reset, the discharge of C
T
is not influenced by the CK input.
PR
(4) C changes from the discharge into the charge if the clock (Negative edge) is input to the CK terminal
while discharging C
(5) C changes from the charge into the discharge when the voltage of C
threshold ( : = 1.4 V) .
(4) and (5) are repeated while a normal clock is input by the logic system.
(6) When the clock is cut off, gets, and the voltage of C
"Low" and RESET goes "High".
Discharge time of C
T
(ms) : = 100
WD
Because the charging time of C
of reset of the clock, T
(7) Reset time in operating watch-dog timer:T
threshold ( : = 1.4 V) for reset.
T
(ms) : = 20
WR
Reset of the output is released after C
after that if the clock is normally input, operation repeats (4) and (5) , when the clock is cut off, operation
repeats (6) and (7) .
(8) When Vcc falls on V
(9) When Vcc goes up to V
When Vcc is momentarily low,
After falling V
or less Vcc, the time to going up is the standard value of the Vcc input pulse width in V
SL
more.
After the charge of C
(10) Reset of the output is released after T
After that, when Vcc becomes V
(11) While power supply is off, when Vcc becomes V
(12) The reset output is maintained until Vcc becomes 0.8 V when Vcc falls on 0 V.
6
( : = 4.3V) , the charge with C
SH
(ms) : = 1000
C
( F)
PR
T
starts, and watch-dog timer operation starts.
T
.
T
until reset is output: T
T
WD
C
( F)
T
is added at accurate time from stop of the clock and getting to the output
T
becomes maximum T
WD
WR
C
( F)
T
reaches an off threshold for reset, and C
T
( : = 4.2 V) , reset is output. C
SL
, the charge with C
SH
is discharged, the charge is started if it is T
T
, after Vcc becomes V
PR
or less, (8) to (10) is repeated.
SL
starts.
T
reaches a constant
T
falls on threshold ( : = 0.4 V) of reset on, RESET goes
T
is watch-dog timer monitoring time.
T
by minimum T
WD
WR
WD
is charging time where the voltage of C
is rapidly discharged of at the same time.
T
is started.
T
or more.
PI
or more, and the watch-dog timer starts.
SH
or less, reset is output.
SL
.
goes up to off
T
starts the discharge,
T
or
SH
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