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MAX6323/MAX6324
μP Supervisory Circuits with Windowed
(Min/Max) Watchdog and Manual Reset
General Description
The MAX6323/MAX6324 microprocessor (µP) supervisory circuits monitor power supplies and µP activity in
digital systems. A watchdog timer looks for activity outside 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 VCC = +1.2V.
The RESET output is either push-pull (MAX6323) or
open-drain (MAX6324). RESET is asserted low when
VCC falls below the reset threshold, or when the manual
reset input (MR) is asserted low. RESET remains asserted for at least 100ms after VCC rises above the reset
threshold and MR is deasserted.
The watchdog pulse output (WDPO) utilizes an opendrain 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 lasertrimmed 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).
Applications
●●
●●
●●
●●
Automotive
Industrial
Medical
Embedded Control Systems
Features
●● Min/Max (Windowed) Watchdog,
8 Factory-Trimmed Timing Options
●● Pulsed Open-Drain, Active-Low Watchdog Output
●● Power-On Reset
●● Precision Monitoring of +2.5V, +3.0V, +3.3V,
and +5.0V Power Supplies
●● Open-Drain or Push-Pull RESET Outputs
●● Low-Power Operation (23µA typ)
●● Debounced Manual Reset Input
●● Guaranteed Reset Valid to VCC = +1.2V
●● AEC-Q100 Qualified MAX6324HUT44/V+T
Ordering Information
TEMP
RANGE
PART
MAX6323_UT_ _-T
PINPACKAGE
-40°C to +125°C 6 SOT23
RESET
OUTPUT
Push-Pull
Ordering Information continued at end of data sheet.
*These devices are factory trimmed to one of eight watchdogtimeout 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 twodigit 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).
/V denotes an automotive qualified part.
Devices are available in both leaded and lead-free packaging.
Specify lead-free by replacing “-T” with “+T” when ordering.
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
increment requirement of 2500 pieces. Nonstandard versions
have an order increment requirement of 10,000 pieces. Contact
factory for availability of nonstandard versions.
Watchdog Timeout
Pin Configuration
WATCHDOG TIMEOUT*
TOP VIEW
SUFFIX
MR 1
GND 2
MAX6323
MAX6324
WDI 3
6
RESET
5
WDPO
4
VCC
SOT23
Typical Operating Circuit appears at end of data sheet.
19-1838; Rev 8; 12/18
FAST
SLOW
MAX
UNITS
MIN
A
1.5
ms
10
B
15
ms
100
C
15
ms
300
D
15
ms
10
E
15
ms
60
F
23
ms
47
G
39
ms
82
H
719
ms
1.3
*See Figure 1 for operation.
UNITS
ms
s
ms
s
MAX6323/MAX6324
μP Supervisory Circuits with Windowed
(Min/Max) Watchdog and Manual Reset
Absolute Maximum Ratings
Terminal Voltage (with respect to GND)
VCC....................................................................-0.3V to +6.0V
MR, RESET (MAX6323), WDI............... -0.3V to (VCC + 0.3V)
WDPO, RESET (MAX6324)..............................-0.3V to +6.0V
Input Current, VCC, WDI, MR..............................................20mA
Output Current, RESET, WDPO.........................................20mA
Rate of Rise, VCC...........................................................100V/µs
Continuous Power Dissipation (TA = +70°C)
6-Pin SOT23 (derate 8.7mW/°C above +70°C)...........696mW
Operating Temperature Range.......................... -40°C to +125°C
Junction Temperature.......................................................+150°C
Storage Temperature Range............................. -65°C to +150°C
Lead Temperature (soldering, 10s).................................. +300°C
Soldering Temperature (reflow)
Lead(Pb)-Free..............................................................+260°C
Containing Lead...........................................................+240°C
Stresses beyond those listed under “Absolute Maximum Ratings” may cause permanent damage to the device. These are stress ratings only, and functional operation of the device at these
or any other conditions beyond those indicated in the operational sections of the specifications is not implied. Exposure to absolute maximum rating conditions for extended periods may affect
device reliability.
Package Information
6 SOT23
PACKAGE CODE
U6+1/U6+1A
Outline Number
21-0058
Land Pattern Number
90-0175
Thermal Resistance, Single-Layer Board:
Junction to Case (θJC)
80°C/W
Thermal Resistance, Multi-Layer Board:
Junction to Ambient (θJA)
115°C/W
Junction to Case (θJC)
80°C/W
For the latest package outline information and land patterns (footprints), go to www.maximintegrated.com/packages. Note that a “+”,
“#”, or “-” in the package code indicates RoHS status only. Package drawings may show a different suffix character, but the drawing
pertains to the package regardless of RoHS status.
Package thermal resistances were obtained using the method described in JEDEC specification JESD51-7, using a four-layer board.
For detailed information on package thermal considerations, refer to www.maximintegrated.com/thermal-tutorial.
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Maxim Integrated │ 2
MAX6323/MAX6324
μP Supervisory Circuits with Windowed
(Min/Max) Watchdog and Manual Reset
Electrical Characteristics
(VCC = full range, TA = -40°C to +125°C, unless otherwise noted. Typical values are at VCC = 3V, TA = +25°C.) (Note 1)
PARAMETER
SYMBOL
Operating Voltage Range
VCC
Supply Current
ICC
Reset Threshold Voltage
Reset Timeout Delay
VTH
tRP
VCC to RESET Delay
WDPO, RESET Output Voltage
RESET Output Voltage
(MAX6323)
WDPO, RESET Output Leakage
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CONDITIONS
MIN
TYP
1.2
No load, RESET
deasserted
VOH
ILKG
UNITS
5.5
V
VCC = 2.5V or 3.3V
23
45
VCC = 5.5
27
57
MAX632_ _UT46
4.50
4.63
4.75
MAX632_ _UT44
4.25
4.38
4.50
MAX632_ _UT31
3.00
3.08
3.15
MAX632_ _UT29
2.85
2.93
3.00
MAX632_ _UT26
2.55
2.63
2.70
MAX632_ _UT23
2.25
2.32
2.38
RESET deasserted
100
180
280
10mV/ms, VTH +100mV to VTH - 100mV
VOL
MAX
20
0.4
ISINK = 3.2mA, VCC = 4.25V
(MAX632_ _UT44, MAX632_ _UT46)
0.4
ISINK = 100μA, VCC > 1.2V,
RESET asserted
0.4
0.8 x VCC
ISOURCE = 800μA, VCC = 4.75V, RESET
deasserted, (MAX632_ _UT44,
MAX632_ _UT46)
VCC - 1.5
VRESET = VWDPO = +5.5V, RESET,
WDPO deasserted
V
ms
µs
ISINK = 1.2mA, VCC = 2.25V
(MAX632_ _UT23, MAX632_ _UT26,
MAX632_ _UT29, MAX632_ _UT31)
ISOURCE = 500μA, VCC = 3.15V,
RESET deasserted (MAX632_ _UT23,
MAX632_ _UT26, MAX632_ _UT29,
MAX632_ _UT31)
µA
V
V
1
µA
Maxim Integrated │ 3
MAX6323/MAX6324
μP Supervisory Circuits with Windowed
(Min/Max) Watchdog and Manual Reset
Electrical Characteristics (continued)
(VCC = full range, TA = -40°C to +125°C, unless otherwise noted. Typical values are at VCC = 3V, TA = +25°C.) (Note 1)
PARAMETER
SYMBOL
CONDITIONS
MIN
TYP
MAX
UNITS
WATCHDOG INPUT AND OUTPUT
Watchdog Timeout (Fast)
(Notes 2, 3)
Watchdog Timeout (Slow)
(Note 4)
tWD1
tWD2
MAX632_AUT_ _
1
1.5
MAX632_BUT_ _
10
15
MAX632_CUT_ _
10
15
MAX632_DUT_ _
10
15
MAX632_EUT_ _
10
15
MAX632_FUT_ _
17
23
MAX632_GUT_ _
29
39
MAX632_HUT_ _
543
719
MAX632_AUT_ _
10
15
MAX632_BUT_ _
100
150
MAX632_CUT_ _
300
450
MAX632_DUT_ _
10
15
MAX632_EUT_ _
60
90
MAX632_FUT_ _
47
63
MAX632_GUT_ _
82
108
MAX632_HUT_ _
1.3
1.8
Minimum Watchdog Input
Pulse Width
300
WDI Glitch Immunity
WDI Input Voltage
VCC = 5.5V
100
VIL
-1.5
-1
VWDI = VCC
WDPO Pulse Width
VIL = 0.8V, VIH = 0.75V x VCC
s
ms
s
ns
0.8
VWDI = 0V
WDI Input Current
ms
ns
0.75 x VCC
VIH
ms
0.5
1
1.5
1
3
V
µA
ms
MANUAL RESET INPUT
MR Input Voltage
0.7 x VCC
VIH
VIL
0.3 x VCC
MR Minimum Pulse Width
1
V
µs
MR Glitch Immunity
VCC = 2.5V
100
ns
MR to Reset Delay
VCC = 2.5V
120
ns
85
kΩ
MR Pullup Resistance
50
Note 1: Devices are tested at TA = +25°C and guaranteed by design for TA = TMIN to TMAX, as specified.
Note 2: WDPO will pulse low if a falling edge is detected on WDI before this timeout period expires.
Note 3: To avoid a potential fake fault, the first WDI pulse after the rising edge of RESET or WDPO will not create a fast watchdog
timeout fault.
Note 4: WDPO will pulse low if no falling edge is detected on WDI after this timeout period expires.
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Maxim Integrated │ 4
MAX6323/MAX6324
μP Supervisory Circuits with Windowed
(Min/Max) Watchdog and Manual Reset
Typical Operating Characteristics
(VCC = full range, TA = +25°C, unless otherwise noted.)
10
VCC = 1.0V
5
0
-40
-20
0
20
40
60
10
5
0
80
VOD = 100mV
NORMALIZED RESET THRESHOLD
vs. TEMPERATURE
-40
-20
40
60
MAX6323/24-05
1.002
1.000
0.998
0.996
-40
-20
0
20
40
60
80
NORMALIZED WATCHDOG OUTPUT
PULSE WIDTH vs. TEMPERATURE
1.000
0.999
0.998
0.997
0.996
0
20
40
TEMPERATURE (°C)
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MAX6323/24-03
-20
60
80
1.008
1.006
1.004
1.002
1.000
0.998
0.996
0.994
0.992
-40
-20
0
20
40
TEMPERATURE (°C)
0
20
40
60
80
NORMALIZED WATCHDOG TIMEOUT
PERIOD (FAST) vs. TEMPERATURE
1.008
1.006
1.004
1.002
1.000
0.998
0.996
0.994
0.992
-40
-20
0
20
40
60
80
TEMPERATURE (°C)
MAXIMUM TRANSIENT DURATION
vs. RESET THRESHOLD OVERDRIVE
MAX6323/24-08
NORMALIZED WATCHDOG TIMEOUT
PERIOD (SLOW) vs. TEMPERATURE
-20
-40
TEMPERATURE (°C)
TEMPERATURE (°C)
1.001
-40
40
0
80
TEMPERATURE (°C)
1.002
0.995
60
1.004
0.994
80
MAX6323/24-07
NORMALIZED WATCHDOG TIMEOUT PERIOD (SLOW)
1.003
20
40
1.006
POWER-UP RESET TIMEOUT
MAX6323/24-04
0.9985
0
20
1.008
NORMALIZED WATCHDOG OUTPUT PULSE WIDTH (µs)
RESET THRESHOLD
0.9990
-20
0
NORMALIZED POWER-UP RESET TIMEOUT
vs. TEMPERATURE
0.9995
-40
60
TEMPERATURE (°C)
1.0000
0.9980
80
20
TEMPERATURE (°C)
1.0005
100
MAX6323/24-06
15
15
120
60
80
400
VOD = VTH - VCC
350
MAX6323/24-09
VCC = 3.3V
20
NORMALIZED WATCHDOG TIMEOUT PERIOD (FAST)
20
140
MR TO RESET DELAY (ns)
25
VOD = 20mV
MAXIMUM TRANSIENT DURATION (µs)
SUPPLY CURRENT (µA)
30
25
MR TO RESET DELAY
vs. TEMPERATURE
160
MAX6323/24-02
VCC = 5.5V
35
POWER-DOWN RESET DELAY
vs. TEMPERATURE
30
POWER-DOWN RESET DELAY (µs)
40
MAX6323/24-01
SUPPLY CURRENT vs. TEMPERATURE
300
250
RESET ASSERTED
ABOVE THIS LINE
200
150
100
50
0
MAX632_AUT23
1
10
100
1000
RESET COMPARATOR OVERDRIVE (mV)
Maxim Integrated │ 5
MAX6323/MAX6324
μP Supervisory Circuits with Windowed
(Min/Max) Watchdog and Manual Reset
Typical Operating Characteristics (continued)
(VCC = full range, TA = +25°C, unless otherwise noted.)
SLOW WATCHDOG TIMEOUT PERIOD
FAST WATCHDOG TIMEOUT PERIOD
MAX6323/24-10
MAX6323/24-11
WDI
2V/div
WDI
2V/div
WDPO
2V/div
WDPO
2V/div
MAX6323AUT23
MAX6323AUT23
500µs/div
5ms/div
Pin Description
PIN
NAME
FUNCTION
1
MR
2
GND
Ground
3
WDI
Watchdog Input. The internal watchdog timer clears to zero on the falling edge of WDI or when RESET goes
high. If WDI sees another falling edge within the factory-trimmed watchdog window, WDPO will
remain unasserted. Transitions outside this window, either faster or slower, will cause WDPO to pulse
low for 1ms (typ).
4
VCC
Supply Voltage for the Device. Input for VCC reset monitor. For noisy systems, bypass VCC with a 500pF
(min) capacitor.
5
WDPO
Watchdog Pulse Output. The open-drain WDPO output is pulsed low for 1ms (typ) upon detection of a fast
or slow watchdog fault. WDPO is only active when RESET is high.
6
RESET
Active-Low. Reset is asserted when VCC drops below VTH and remains asserted until VCC rises above
VTH for the duration of the reset timeout period. The MAX6323 has a push-pull output and the MAX6324
has an open-drain output. Connect a pullup resistor from RESET to any supply voltage up to +6V.
Active-Low, Manual Reset Input. When MR is asserted low, RESET is asserted low, the internal watchdog
timer is reset to zero, and WDPO is reset to high impedance (open drain). After the rising edge of MR,
RESET is asserted for at least 100ms. Leave MR unconnected or connect to VCC if unused.
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Maxim Integrated │ 6
MAX6323/MAX6324
μP Supervisory Circuits with Windowed
(Min/Max) Watchdog and Manual Reset
tWD1 (min)
)
tWD1 (max)
tWD2 (min)
tWD2 (max)
POSSIBLE STATES
GUARANTEED TO
ASSERT WDPO
GUARANTEED NOT TO
ASSERT WDPO
*UNDETERMINED
GUARANTEED TO
ASSERT WDPO
*UNDETERMINED
CONDITION 1
FAST FAULT
CONDITION 2
NORMAL OPERATION
CONDITION 3
SLOW FAULT
*UNDETERMINED STATES MAY OR MAY NOT GENERATE A FAULT CONDITION.
Figure 1. Detailed Watchdog Input Timing Relationship
Detailed Description
The MAX6323/MAX6324 μP supervisory circuits maintain
system integrity by alerting the μP to fault conditions. In
addition to a standard VCC monitor (for power-on reset,
brownout detect, and power-down reset), the devices
include a sophisticated watchdog timer that detects when
the processor is running outside an expected window of
operation for a specific application. The watchdog signals
a fault when the input pulses arrive too early (faster than
the selected tWD1 timeout period) or too late (slower than
the selected tWD2 timeout period) (Figure 1). Incorrect
timing can lead to poor or dangerous system performance
in tightly controlled operating environments. Incorrect
timing could be the result of improper μP clocking or code
execution errors. If a timing error occurs, the MAX6323/
MAX6324 issue a watchdog pulse output, independent
from the reset output, indicating that system maintenance
may be required.
Watchdog Function
A pulse on the watchdog output WDPO can be triggered
by a fast fault or a slow fault. If the watchdog input (WDI)
has two falling edges too close to each other (faster
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than tWD1) (Figure 2) or falling edges that are too far
apart (slower than tWD2) (Figure 3), WDPO is pulsed
low. Normal watchdog operation is displayed in Figure 4
(WDPO is not asserted). The internal watchdog timer is
cleared when a WDI falling edge is detected within the
valid watchdog window or when the device’s RESET or
WDPO outputs are deasserted. All WDI input pulses are
ignored while either RESET or WDPO is asserted. Figure
1 identifies the input timing regions where WDPO fault
outputs will be observed with respect to tWD1 and tWD2.
After RESET or WDPO deasserts, the first WDI falling
edge is ignored for the fast fault condition (Figure 2).
Upon detecting a watchdog fault, the WDPO output
will pulse low for 1ms. WDPO is an open-drain output.
Connect a pullup resistor on WDPO to any supply up to
+6V.
VCC Reset
The MAX6323/MAX6324 also include a standard VCC
reset monitor to ensure that the μP is started in a
known state and to prevent code execution errors
during power-up, power-down, or brownout conditions.
RESET is asserted whenever the VCC supply voltage
Maxim Integrated │ 7
MAX6323/MAX6324
μP Supervisory Circuits with Windowed
(Min/Max) Watchdog and Manual Reset
tWDI < tWD1 (min)
RESET
WDI
WDPO
FAST FAULT
Figure 2. Fast Fault Timing
RESET
tWDI < tWD2 (max)
WDI
WDPO
SLOW FAULT
Figure 3. Slow Fault Timing
RESET
tWD1 (max) < tWDI < tWD2 (min)
WDI
H
WDPO
L
NORMAL OPERATION (NO PULSING, OUTPUT STAYS HIGH)
Figure 4. Normal Operation, WDPO Not Asserted
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Maxim Integrated │ 8
MAX6323/MAX6324
μP Supervisory Circuits with Windowed
(Min/Max) Watchdog and Manual Reset
VTH
VCC
100ms (min)
100ms (min)
120ns (typ)
20µs (typ)
RESET
MR
1µs (min)
Figure 5. RESET Timing Relationship
falls below the preset threshold or when the manual
reset input (MR) is asserted. The RESET output remains
asserted for at least 100ms after VCC has risen above
the reset threshold and MR is deasserted (Figure 5).
For noisy environments, bybass VCC with a 500pF (min)
capacitor to ensure correct operation.
The MAX6323 has a push-pull output stage, and the
MAX6324 utilizes an open-drain output. Connect a
pullup resistor on the RESET output of the MAX6324 to
any supply up to +6V. Select a resistor value large enough
to register a logic low (see Electrical Characteristics) and
small enough to register a logic high while supplying all
input leakage currents and leakage paths connected
to the RESET line. A 10kΩ pullup is sufficient in most
applications.
Manual Reset Input
Many μP-based products require manual reset capability
to allow an operator or external logic circuitry to initiate a
reset. The manual reset input (MR) can connect directly to
a switch without an external pullup resistor or debouncing
network. MR is internally pulled up to VCC and, therefore, can be left unconnected if unused. MR is designed
to reject fast, negative-going transients (typically 100ns
pulses), and it must be held low for a minimum of 1μs
to assert the reset output (Figure 5). A 0.1μF capacitor
from MR to ground provides additional noise immunity.
After MR transitions from low to high, reset will remain
asserted for the duration of the reset timeout period, at
least 100ms.
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Applications Information
Negative-Going VCC Transients
The MAX6323/MAX6324 are relatively immune to shortduration negative-going VCC transients (glitches), which
usually do not require the entire system to shut down.
Typically, 200ns large-amplitude pulses (from ground
to VCC) on the supply will not cause a reset. Lower
amplitude pulses result in greater immunity. Typically,
a VCC transient that falls 100mV below the reset
threshold and lasts less than 20μs will not trigger a
reset (see Typical Operating Characteristics). An optional
0.1μF bypass capacitor mounted close to VCC provides
additional transient immunity.
Ensuring a Valid Reset Output
Down to VCC = 0V
When VCC falls below +1.2V, the MAX6323 RESET output no longer sinks current; it becomes an open circuit.
Therefore, high-impedance CMOS logic inputs connected
to RESET can drift to undetermined voltages. This does
not present a problem in most applications, since most
μPs and other circuitry are inoperative with VCC below
+1.2V. However, in applications where RESET must be
valid down to 0, adding a pulldown resistor to RESET
causes any stray leakage currents to flow to ground, holding RESET low (Figure 6). R1’s value is not critical; 100kΩ
is large enough not to load RESET and small enough to
pull RESET to ground. This scheme does not work with
the open-drain output of the MAX6324.
Maxim Integrated │ 9
MAX6323/MAX6324
μP Supervisory Circuits with Windowed
(Min/Max) Watchdog and Manual Reset
VCC
VCC
VCC
VCC
VCC
MAX6323
MAX6324
µP
GND
R1
100k
Figure 6. RESET Valid to VCC = Ground Circuit
Interfacing to μPs with
Bidirectional Reset Pins
Since the RESET output on the MAX6324 is opendrain, this device easily interfaces with μPs that have
bidirectional reset pins, such as the Motorola 68HC11.
Connecting the μP supervisor’s RESET output directly
to the microcontroller’s (μC’s) RESET pin with a single
pullup resistor allows either device to assert reset
(Figure 7).
GND
Generally, the pullup resistor connected to the MAX6324
will connect to the supply voltage that is being monitored
at the IC’s VCC pin. However, some systems may use
the open-drain output to level-shift from the monitored
supply to reset circuitry powered by some other supply
(Figure 8). Keep in mind that as the MAX6324’s VCC
decreases below +1.2V, so does the IC’s ability to sink
current at RESET. Also, with any pullup resistor, RESET
will be pulled high as VCC decays toward 0. The voltage
where this occurs depends on the pullup resistor value
and the voltage to which it is connected.
Watchdog Software Considerations
To help the watchdog timer monitor software execution
more closely, set and reset the watchdog input at different
points in the program, rather than “pulsing” the watchdog
input high-low-high or low-high-low. This technique avoids
a “stuck” loop in which the watchdog time would continue
GND
Figure 7. Interfacing to μPs with Bidirectional Reset Pins
+3.3V
+5.0V
RPULLUP
VCC
VCC
MAX6324
MAX6324 Open-Drain RESET Output
Allows Use with Multiple Supplies
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RESET
INPUT
RESET
RESET
RESET
GND
5V SYSTEM
RESET
INPUT
GND
Figure 8. MAX6324 Open-Drain RESET Output Allows Use
with Multiple Supplies
to be reset within the loop, keeping the watchdog from
timing out.
Figure 9 shows an example of a flow diagram where the
I/O driving the watchdog input is set high at the beginning
of the program, set low at the beginning of every subroutine or loop, then set high again when the program returns
to the beginning. If the program should “hang” in any subroutine, the problem would be quickly corrected, since the
I/O is continually set low and the watchdog time is allowed
to time out, causing a reset or interrupt to be issued.
Maxim Integrated │ 10
MAX6323/MAX6324
μP Supervisory Circuits with Windowed
(Min/Max) Watchdog and Manual Reset
WDPO to MR Loopback
An error detected by the watchdog often indicates that
a problem has occurred in the μP code execution.
This could be a stalled instruction or a loop from which
the processor cannot free itself. If the μP will still respond
to a nonmaskable input (NMI), the processor can be
redirected to the proper code sequence by connecting the
WDPO output to an NMI input. Internal RAM data should
not be lost, but it may have been contaminated by the
same error that caused the watchdog to time out.
START
SET WDI
LOW
SUBROUTINE OR
PROGRAM LOOP
SET WDI HIGH
If the processor will not recognize NMI inputs, or if the
internal data is considered potentially corrupted when a
watchdog error occurs, the processor should be restarted
with a reset function. To obtain proper reset timing
characteristics, the WDPO output should be connected
to the MR input, and the RESET output should drive the
μP RESET input (Figure 10). The short 1ms WDPO pulse
output will assert the manual reset input and force the
RESET output to assert for the full reset timeout period
(100ms min). All internal RAM data is lost during the reset
period, but the processor is guaranteed to begin in the
proper operating state.
RETURN
END
Figure 9. Watchdog Flow Diagram
VCC
500pF
VCC
VCC
*RPULLUP
MAX6323
MAX6324
RESET
MR
WDI
GND
µP
RESET
I/O
WDPO
*MAX6324 ONLY
Figure 10. WDPO to MR Loopback Circuit
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Maxim Integrated │ 11
MAX6323/MAX6324
μP Supervisory Circuits with Windowed
(Min/Max) Watchdog and Manual Reset
Standard Versions
Reset Threshold Range
(-40°C to +125°C)
MAX6323AUT29
MAX6324AUT29
MAX6323AUT46
MAX6324AUT46
SUFFIX
MIN
TYP
MAX
MAX6323CUT29
MAX6324BUT29
46
4.50
4.63
4.75
MAX6323CUT46
MAX6324BUT46
44
4.25
4.38
4.50
MAX6323DUT29
MAX6324EUT29
31
3.00
3.08
3.15
MAX6323DUT46
MAX6324EUT46
29
2.85
2.93
3.00
MAX6323HUT29
MAX6324HUT29
26
2.55
2.63
2.70
MAX6323HUT46
MAX6324HUT46
23
2.25
2.32
2.38
Ordering Information (continued)
TEMP
RANGE
PART
PINPACKAGE
V
Chip Information
RESET
OUTPUT
-40°C to +125°C 6 SOT23
Open
Drain
MAX6324_UT_ _/V+T -40°C to +125°C 6 SOT23
Open
Drain
MAX6324HUT44/V+T -40°C to +125°C 6 SOT23
Open
Drain
MAX6324_UT_ _-T
UNITS
TRANSISTOR COUNT: 1371
PROCESS: BiCMOS
*These devices are factory trimmed to one of eight watchdogtimeout 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 twodigit 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).
/V denotes an automotive qualified part.
Devices are available in both leaded and lead-free packaging.
Specify lead-free by replacing “-T” with “+T” when ordering.
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
increment requirement of 2500 pieces. Nonstandard versions
have an order increment requirement of 10,000 pieces. Contact
factory for availability of nonstandard versions.
www.maximintegrated.com
Maxim Integrated │ 12
MAX6323/MAX6324
μP Supervisory Circuits with Windowed
(Min/Max) Watchdog and Manual Reset
Typical Operating Circuit
VCC
500pF
VCC
VCC
*RPULLUP
MAX6323
MAX6324
RESET
MR
WDI
GND
WDPO
µP
RESET
I/O
NMI
*MAX6324 ONLY
www.maximintegrated.com
Maxim Integrated │ 13
MAX6323/MAX6324
μP Supervisory Circuits with Windowed
(Min/Max) Watchdog and Manual Reset
Revision History
REVISION
NUMBER
REVISION
DATE
PAGES
CHANGED
0
10/00
Initial release
5
5/10
Updated the Ordering Information and Absolute Maximum Ratings.
6
1/11
Corrected placement of /V in the Ordering Information section
7
3/18
Updated Features section and Ordering Information table
1, 12
8
12/18
Updated Package Information
2, 12
DESCRIPTION
—
1, 2, 10
11
For pricing, delivery, and ordering information, please visit Maxim Integrated’s online storefront at https://www.maximintegrated.com/en/storefront/storefront.html.
Maxim Integrated cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in a Maxim Integrated product. No circuit patent licenses
are implied. Maxim Integrated reserves the right to change the circuitry and specifications without notice at any time. The parametric values (min and max limits)
shown in the Electrical Characteristics table are guaranteed. Other parametric values quoted in this data sheet are provided for guidance.
Maxim Integrated and the Maxim Integrated logo are trademarks of Maxim Integrated Products, Inc.
© 2018 Maxim Integrated Products, Inc. │ 14