19-1838; Rev 1; 1/01
µP Supervisory Circuits with Windowed
(Min/Max) Watchdog and Manual Reset
General Description
The MAX6323/MAX6324 microprocessor (µP) supervi-
sory circuits monitor power supplies and µP activity in
digital systems. A watchdog timer looks for activity out-
side an expected window of operation. Six laser-
trimmed reset thresholds are available with ±2.5%
accuracy from +2.32V to +4.63V. Valid
RESET
output is
guaranteed down to V
CC
= +1.2V.
The
RESET
output is either push-pull (MAX6323) or
open-drain (MAX6324).
RESET
is asserted low when
V
CC
falls below the reset threshold, or when the manual
reset input (MR) is asserted low.
RESET
remains assert-
ed for at least 100ms after V
CC
rises above the reset
threshold or
MR
is deasserted.
The watchdog pulse output (WDPO) utilizes an open-
drain configuration. It can be triggered either by a fast
timeout fault (watchdog input pulses are too close to
each other) or a slow timeout fault (no watchdog input
pulse is observed within the timeout period). The
watchdog timeout is measured from the last falling
edge of watchdog input (WDI) with a minimum pulse
width of 300ns.
WDPO
is asserted for 1ms when a fault
is observed. Eight laser-trimmed timeout periods are
available.
The MAX6323/MAX6324 are offered in a 6-pin SOT23
package and operate over the extended temperature
range (-40°C to +125°C).
o
Min/Max (Windowed) Watchdog,
8 Factory-Trimmed Timing Options
o
Pulsed Open-Drain, Active-Low Watchdog Output
o
Power-On Reset
o
Precision Monitoring of +2.5V, +3.0V, +3.3V,
and +5.0V Power Supplies
o
Open-Drain or Push-Pull
RESET
Outputs
o
Low-Power Operation (23µA typ)
o
Debounced Manual Reset Input
o
Guaranteed Reset Valid to V
CC
= +1.2V
Features
MAX6323/MAX6324
Ordering Information
PART*
TEMP.
RANGE
PIN-
PACKAGE
RESET
OUTPUT
Applications
Automotive
Industrial
Medical
Embedded Control Systems
MAX6323_UT__-T
-40°C to +125°C 6 SOT23-6 Push-Pull
MAX6324_UT__-T
-40°C to +125°C 6 SOT23-6 Open Drain
*These devices are factory trimmed to one of eight watchdog-
timeout windows and one of six reset voltage thresholds. Insert
the letter corresponding to the desired watchdog-timeout window
(A, B, C, D, E, F, G, or H) into the blank following the number
6323 or 6324 (see Watchdog Timeout table). Insert the two-digit
code (46, 44, 31, 29, 26, or 23) after the letters UT for the desired
nominal reset threshold (see Reset Threshold Range table at end
of data sheet).
Note:
There are eight standard versions of each device available
(see Standard Versions table). Sample stock is generally held on
standard versions only. Standard versions have an order incre-
ment requirement of 2500 pieces. Nonstandard versions have an
order increment requirement of 10,000 pieces. Contact factory for
availability of nonstandard versions.
Pin Configuration
TOP VIEW
MR
1
6
RESET
Watchdog Timeout
SUFFIX
A
B
C
D
E
F
G
H
WATCHDOG TIMEOUT*
FAST
SLOW
MAX
MIN
UNITS
UNITS
1.5
ms
10
15
ms
100
ms
15
ms
300
15
ms
10
s
15
ms
60
23
ms
47
ms
39
ms
82
719
ms
1.3
s
GND
2
MAX6323
MAX6324
5
WDPO
WDI
3
4
V
CC
SOT23
Typical Operating Circuit appears at end of data sheet.
*See
Figure 1 for operation.
1
________________________________________________________________
Maxim Integrated Products
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