MB3793-30A Fujitsu Media Devices, MB3793-30A Datasheet - Page 13

• Manufacturer Part Number: MB3793-30A
• Description: POWER-VOLTAGE MONITORING IC WITH WATCHDOG TIMER
• Manufacturer: Fujitsu Media Devices

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(10) When the CTP pin voltage reaches or exceeds V
(7) When a certain period of time t
(8) If V
(9) When V
(11) Making the inhibit pin active (setting the INH pin to “H” from “L”) forces the watchdog timer to stop
(12) Canceling the inhibit input (setting the INH pin to “L” from “H”) restarts the watchdog timer.
(13) The reset signal is output when the power supply is turned off to set V
1. Equation of time-setting capacitances (C
2. Example (when C
after recharging the C
The watchdog timer monitor reset time t
t
The value of D is 55 with V
The MB3793 repeats operations (4) and (5) as long as the CK1/CK2 pin inputs clock pulses. If no clock
pulse is input, the MB3793 repeats operations (6) and (7).
MB3793 outputs a reset signal (setting the RESET pin to “L” level from “H” level).
The value of V
the watchdog timer. It repeats operations (4) and (5) as long as the CK1/CK2 pin inputs clock pulses.
operation.
This stops only the watchdog timer, leaving the MB3793 monitoring V
The watchdog timer remains inactive unless the inhibit input is canceled.
The inhibition (INH) pin must be connecting a voltage of more low impedance, to evade of the noise.
WR
CC
(ms)
Values of A, B, C, and D
is lowered to the fall-time detected voltage (V
time
(ms)
CC
.
. =
t
t
t
PR
WD
WR
reaches or exceeds V
D x C
[ms]
[ms]
[ms]
SL
TP
1300
is 3.0 V (Typ) .
750
A
.
=
( F)
.
=
.
.
.
=
.
A
B
TP
TP
D
), the MB3793 cancels the reset signal and starts operating the watchdog timer.
= 0.1
Symbol
C
C
C
TP
TW
t
t
t
1600
1500
CC
TP
WD
WR
PR
[ F]
B
[ F]
[ F]
= 3.3 V.
WR
F and
SH
has passed (until the CTP pin voltage reaches or exceeds Vth again
again, the MB3793 starts charging the C
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C
WR
C
0
0
TW
is set with the following equation:
= 0.01
V
th
CC
, the MB3793 cancels the reset and restarts operating
TP
100
55
= 3.3 V
D
SL
5.5
75
16
and C
F
) or less, the CTP pin voltage decreases and the
)
TW
V
V
) and set time
Remark
CC
CC
= 3.3 V
= 5.0 V
V
CC
CC
CC
(operations (8) to (10)).
to V
= 5.0 V
130
15
10
TP
.
SL
MB3793
or less.
-30A
13