Datasheet
(V
CC
= +5V, T
A
= +25°C, unless otherwise noted.)
PIN
NAME FUNCTION
MAX6746
MAX6747
MAX6748–
MAX6751
MAX6752
MAX6753
1 — — MR
Manual-Reset Input. Pull MR low to manually reset the device. Reset
remains asserted for the reset timeout period after MR is released.
— 1 — RESET IN
Reset Input. High-impedance input to the adjustable reset comparator.
Connect RESET IN to the center point of an external resistor-divider to
set the threshold of the externally monitored voltage.
— — 1 SET0
Logic Input. SET0 selects watchdog window ratio or disables the
watchdog timer. See Table 1.
2 2 2 SWT
Watchdog Timeout Input.
MAX6746–MAX6751: Connect a capacitor between SWT and ground to
set the basic watchdog timeout period (t
WD
). Determine the period by
the formula t
WD
= 5.06 x 10
6
x C
SWT
with t
WD
in seconds and C
SWT
in Farads. Extend the basic watchdog timeout period by using the WDS
input. Connect SWT to ground to disable the watchdog timer function.
MAX6752/MAX6753: Connect a capacitor between SWT and ground
to set the slow watchdog timeout period (t
WD2
). Determine the slow
watchdog period by the formula: t
WD2
= 0.65 x 10
9
x C
SWT
with t
WD2
in
seconds and C
SWT
in
Farads. The fast watchdog timeout period is set
by pinstrapping SET0 and SET1 (Connect SET0 high and SET1 low to
disable the watchdog timer function.) See Table 1.
3 3 3 SRT
Reset Timeout Input. Connect a capacitor from SRT to GND to select
the reset timeout period. Determine the period as follows: t
RP
= 5.06 x
10
6
x C
SRT
with t
RP
in seconds and C
SRT
in
Farads.
4 4 4 GND Ground
V
CC
TO RESET DELAY
vs. TEMPERATURE (V
CC
FALLING)
MAX6746 toc09
TEMPERATURE (°C)
V
CC
TO RESET DELAY (µs)
1007550250-25
25.4
25.8
26.2
26.6
27.0
25.0
-50 125
V
CC
FALLING AT 1mV/µs
RESET AND WATCHDOG
TIMEOUT PERIOD vs. SUPPLY VOLTAGE
MAX6746 toc10
V
CC
(V)
TIMEOUT PERIOD (ms)
5.55.04.0 4.52.5 3.0 3.52.0
0.44
0.48
0.52
0.56
0.60
0.40
1.5 6.0
C
SWT
= C
SRT
= 100pF
RESET AND WATCHING TIMEOUT
PERIOD vs. SUPPLY VOLTAGE
MAX6746 toc11
V
CC
(V)
TIMEOUT PERIOD (ms)
5.55.04.54.03.53.02.52.0
6.5
7.0
7.5
8.0
8.5
9.0
6.0
1.5 6.0
C
SWT
= C
SRT
= 1500pF
RESET
WATCHDOG
Maxim Integrated
│
5
www.maximintegrated.com
MAX6746–MAX6753 μP Reset Circuits with Capacitor-Adjustable
Reset/Watchdog Timeout Delay
Typical Operating Characteristics (continued)
Pin Conguration