MAX6746 Maxim, MAX6746 Datasheet - Page 5

• Manufacturer Part Number: MAX6746
• Description: UP Reset Circuits with Capacitor-Adjustable Reset/Watchdog Timeout Delay
• Manufacturer: Maxim

(V
CC
MAX6746
MAX6747
27.0
26.6
26.2
25.8
25.4
25.0
= +5V, T
—
—
1
2
3
4
-50
V
µP Reset Circuits with Capacitor-Adjustable
CC
vs. TEMPERATURE (V
-25
FALLING AT 1mV/µs
A
= +25°C, unless otherwise noted.)
V
CC
0
MAX6748–
TEMPERATURE (°C)
MAX6751
TO RESET DELAY
_______________________________________________________________________________________
PIN
25
—
—
1
2
3
4
50
CC
75
FALLING)
MAX6752
MAX6753
100
—
—
1
2
3
4
125
Reset/Watchdog Timeout Delay
RESET IN
0.60
0.56
0.52
0.48
0.44
0.40
Typical Operating Characteristics (continued)
NAME
SET0
GND
SWT
SRT
MR
1.5
C
SWT
2.0
= C
TIMEOUT PERIOD vs. V
2.5 3.0 3.5
RESET AND WATCHDOG
SRT
Manual Reset Input. Pull MR low to manually reset the device. Reset
remains asserted for the reset timeout period after MR is released.
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.
Logic Input. SET0 selects watchdog window ratio or disables the
watchdog timer. See Table 1.
Watchdog Timeout Input.
MAX6746–MAX6751: Connect a capacitor between SWT and ground to
set the basic watchdog timeout period (t
the formula t
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
watchdog period by the formula: t
seconds and C
by pinstrapping SET0 and SET1 (Connect SET0 high and SET1 low to
disable the watchdog timer function.) See Table 1.
Reset Timeout Input. Connect a capacitor from SRT to GND to select
the reset timeout period. Determine the period as follows: t
10
Ground
= 100pF
6
x C
V
SRT
CC
(V)
4.0 4.5
with t
WD
SWT
= 5.06 x 10
RP
5.0
CC
in seconds and C
in Farads. The fast watchdog timeout period is set
5.5
6.0
6
x C
FUNCTION
SWT
9.0
8.5
8.0
7.5
7.0
6.5
6.0
WD2
1.5
with t
SRT
C
= 0.65 x 10
SWT
WD2
RESET AND WATCHING TIMEOUT
2.0
WD
in Farads.
= C
WD
2.5
). Determine the period by
). Determine the slow
SRT
Pin Description
in seconds and C
= 1500pF
PERIOD vs. V
3.0
9
3.5
x C
V
CC
(V)
SWT
4.0
WATCHDOG
CC
4.5
RP
with t
RESET
= 5.06 x
5.0
SWT
WD2
5.5
in
in
6.0
5