________________General Description
The MAX823/MAX824/MAX825* microprocessor (P)
supervisory circuits combine reset output, watchdog,
and manual reset input functions in 5-pin SOT23 and
SC70 packages. They significantly improve system relia-
bility and accuracy compared to separate ICs or discrete
components. The MAX823/MAX824/MAX825 are specifi-
cally designed to ignore fast transients on V
CC
.
Seven preprogrammed reset threshold voltages are
available (see Reset Threshold Table). All three devices
have an active-low reset output, which is guaranteed to
be in the correct state for V
CC
down to 1V. The MAX823
also offers a watchdog input and manual reset input.
The MAX824 offers a watchdog input and a comple-
mentary active-high reset. The MAX825 offers a manual
reset input and a complementary active-high reset. The
Selector Guide explains the functions offered in this
series of parts.
________________________Applications
Computers and Controllers
Embedded Controllers
Intelligent Instruments
Automotive Systems
Critical P Monitoring
Portable/Battery-Powered Equipment
Features
o Precision Monitoring of +2.5V, +3V, +3.3V, and
+5V Power Supplies
o Operating Current: 6A (MAX823L/M) (SC70)
2A (MAX825T/S/R/Z/Y) (SC70)
o Fully Specified Over Temperature
o 140ms min Power-On Reset
o Guaranteed RESET Valid to V
CC
= 1V
o Power-Supply Transient Immunity
o Watchdog Timer with 1.6s Timeout
(MAX823/MAX824)
o Manual Reset Input (MAX823/MAX825)
o No External Components
MAX823/MAX824/MAX825
5-Pin Microprocessor Supervisory Circuits With
Watchdog Timer and Manual Reset
________________________________________________________________ Maxim Integrated Products
1
1
5
2
3
4
1
5
2
3
4
1
5
2
3
4
GND
WDI
V
CC
MAX823
SOT23/SC70
TOP VIEW
MR
RESET
GND
WDI
RESET
V
CC
MAX824
SOT23/SC70
RESET
GND
MR
RESET
V
CC
MAX825
SOT23/SC70
RESET
______________________Selector Guide
19-0487; Rev 4; 7/01
Insert the desired suffix letter (from the Reset Threshold table) into
the blank to complete the part number. All devices are available in
tape-and-reel only. There is a 2500 piece minimum order increment.
MAX823
Active-Low Reset
Active-High Reset
--
FUNCTION
Watchdog Input
MAX824
MAX825
--
Manual Reset Input
--
SUFFIX
RESET
THRESHOLD (V)
L
4.63
M
4.38
T
3.08
S
2.93
R
2.63
Typical Operating Circuit appears at end of data sheet.
Marking Information appears at end of data sheet.
Ordering Information
PART
TEMP. RANGE
PIN-PACKAGE
MAX823_EXK-T
-40C to +85C
5 SC70-5
MAX823_EUK-T
-40C to +125C
5 SOT23-5
MAX824_EXK-T
-40C to +85C
5 SC70-5
Ordering Information continued at end of data sheet.
Reset Threshold Table
Z (SC70 only)
2.32
Y (SC70 only)
2.19
Pin Configurations
*Patents Pending
For pricing, delivery, and ordering information, please contact Maxim/Dallas Direct! at
1-888-629-4642, or visit Maxim's website at www.maxim-ic.com.
MAX823/MAX824/MAX825
5-Pin Microprocessor Supervisory Circuits With
Watchdog Timer and Manual Reset
2
_______________________________________________________________________________________
ABSOLUTE MAXIMUM RATINGS
ELECTRICAL CHARACTERISTICS
(V
CC
= +4.75V to +5.5V for MAX82_L, V
CC
= +4.5V to +5.5V for MAX82_M, V
CC
= +3.15V to +3.6V for MAX82_T, V
CC
= +3V
to +3.6V for MAX82_S, V
CC
= +2.7V to +3.6V for MAX82_R, V
CC
= +2.38V to +2.75V for MAX82_Z, V
CC
= +2.25V to +2.75V for
MAX82_Y, T
A
= T
MIN
to T
MAX
, T
A
= -40
C to +85C (SC70), T
A
= -40
C to +125C (SOT23), unless otherwise noted. Typical values
are at T
A
= +25
C.) (Note 1)
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.
V
CC
........................................................................-0.3V to +6.0V
All Other Pins..............................................-0.3V to (V
CC
+ 0.3V)
Input Current, All Pins Except RESET and RESET..............20mA
Output Current, RESET, RESET ..........................................20mA
Continuous Power Dissipation (T
A
= +70
C)
5-Pin SC70 (derate 3.1mW/
C above +70C)...............247mW
5-Pin SOT23 (derate 7.1mW/
C above +70C).............571mW
Operating Temperature Range
MAX82_EXK......................................................-40
C to +85C
MAX82_EUK ...................................................-40
C to +125C
Storage Temperature Range .............................-65
C to +150C
Lead Temperature (soldering, 10s) .................................+300
C
MAX825T/S/R/Z/Y
PARAMETER
SYMBOL
MIN
TYP
MAX
UNITS
4.56
4.63
4.70
Supply Current
(SOT23 Only)
I
SUPPLY
3
8
A
4.5
12
10
24
4.50
4.75
Operating Voltage Range
MAX825L/M
MAX823L/M
MAX824L/M
1.0
5.5
V
CC
1.2
V
5
12
MAX823T/S/R/Z/Y
MAX824T/S/R/Z/Y
2.59
2.63
2.66
2.55
2.70
T
A
= T
MIN
to T
MAX
T
A
= +25C
MAX82_R
3.04
3.08
3.11
3.00
3.15
T
A
= T
MIN
to T
MAX
T
A
= +25C
MAX82_T
2.89
2.93
2.96
2.85
3.00
T
A
= T
MIN
to T
MAX
T
A
= +25C
CONDITIONS
MAX82_S
MR unconnected
T
A
= T
MIN
to T
MAX
T
A
= +25C
MAX82_L
4.31
4.38
4.45
T
A
= 0C to +70C
T
A
= T
MIN
to T
MAX
4.25
4.50
WDI and MR
unconnected
T
A
= T
MIN
to T
MAX
T
A
= +25C
MAX82_M
MAX825T/S/R/Z/Y
Supply Current
(SC70 Only)
I
SUPPLY
2
6
A
3
8
6
17
MAX825L/M
MAX823L/M
MAX824L/M
4
12
MAX823T/S/R/Z/Y
MAX824T/S/R/Z/Y
MR unconnected
WDI and MR
unconnected
2.28
2.32
2.35
2.25
2.38
Reset Threshold
V
T
A
= T
MIN
to T
MAX
T
A
= +25C
MAX82_Z
(SC70 only)
2.16
2.19
2.22
2.13
2.25
T
A
= T
MIN
to T
MAX
T
A
= +25C
MAX82_Y
(SC70 only)
V
RST
MAX823/MAX824/MAX825
5-Pin Microprocessor Supervisory Circuits With
Watchdog Timer and Manual Reset
_______________________________________________________________________________________
3
PARAMETER
SYMBOL
CONDITIONS
MIN
TYP
MAX
UNITS
MAX82_L/M
10
Reset Threshold Hysteresis
MAX82_T/S/R/Z/Y
5
mV
Reset Threshold Temperature
Coefficient
40
ppm/
C
Reset Timeout Period
t
RP
140
200
280
ms
V
CC
to RESET Delay
V
RST
- V
CC
= 100mV
20
s
MAX82_L/M, V
CC
= V
RST
max,
I
SOURCE
= 120
A
V
CC -
1.5
V
OH
MAX82_T/S/R/Z/Y, V
CC
= V
RST
max,
I
SOURCE
= 30
A
0.8
V
CC
MAX82_L/M, V
CC
= V
RST
min,
I
SINK
= 3.2mA
0.4
MAX82_T/S/R/Z/Y V
CC
= V
RST
min,
I
SINK
= 1.2mA
0.3
T
A
= 0
C to +70C, V
CC
= 1V,
V
CC
falling, I
SINK
= 50
A
0.3
RESET Output Voltage
V
OL
T
A
= T
MIN
to T
MAX
, V
CC
= 1.2V,
V
CC
falling, V
BATT
= 0V, I
SINK
= 100
A
V
MAX82_L/M, RESET = 0V, V
CC
= 5.5V
800
RESET Output Short-Circuit
Current (Note 2)
I
SOURCE
MAX82_T/S/R/Z/Y, RESET = 0V, V
CC
= 3.6V
400
A
V
OH
V
CC
> 1.8V, I
SOURCE
= 150
A
0.8
V
CC
MAX824L/M, MAX825L/M,
V
CC
= V
RST
max, I
SINK
= 3.2mA
0.4
RESET Output Voltage
V
OL
MAX824T/S/R/Z/Y, MAX825T/S/R/Z/Y,
V
CC
= V
RST
max, I
SINK
= 1.2mA
0.3
V
WATCHDOG INPUT (MAX823/MAX824)
Watchdog Timeout Period
t
WD
1.12
1.60
2.40
s
WDI Pulse Width
t
WDI
V
IL
= 0.4V, V
IH
= 0.8
V
CC
50
ns
V
IL
0.3
V
CC
WDI Input Voltage (Note 3)
V
IH
0.7
V
CC
V
WDI = V
CC
, time average
120
160
WDI Input Current (Note 4)
WDI = 0, time average
-20
-15
A
ELECTRICAL CHARACTERISTICS (continued)
(V
CC
= +4.75V to +5.5V for MAX82_L, V
CC
= +4.5V to +5.5V for MAX82_M, V
CC
= +3.15V to +3.6V for MAX82_T, V
CC
= +3V
to +3.6V for MAX82_S, V
CC
= +2.7V to +3.6V for MAX82_R, V
CC
= +2.38V to +2.75V for MAX82_Z, V
CC
= +2.25V to +2.75V for
MAX82_Y, T
A
= T
MIN
to T
MAX
, T
A
= -40
C to +85C (SC70), T
A
= -40
C to +125C (SOT23), unless otherwise noted. Typical values
are at T
A
= +25
C.) (Note 1)
MAX823/MAX824/MAX825
5-Pin Microprocessor Supervisory Circuits With
Watchdog Timer and Manual Reset
4
_______________________________________________________________________________________
Note 1: Over-temperature limits are guaranteed by design and not production tested.
Note 2: The RESET short-circuit current is the maximum pullup current when RESET is driven low by a P bidirectional reset pin.
Note 3: WDI is internally serviced within the watchdog period if WDI is left unconnected.
Note 4: The WDI input current is specified as the average input current when the WDI input is driven high or low. The WDI input is
designed to drive a three-stated output device with a 10A maximum leakage current and a maximum capacitive load of
200pF. This output device must be able to source and sink at least 200A when active.
PARAMETER
SYMBOL
CONDITIONS
MIN
TYP
MAX
U N IT S
MANUAL RESET INPUT (MAX823/MAX825)
V
IL
0.3
V
CC
MR Input Voltage
V
IH
0.7
V
CC
V
MR Pulse Width
1.0
s
MR Noise Immunity (pulse width
with no reset)
100
ns
MR to Reset Delay
500
ns
MR Pullup Resistance
(internal)
35
52
75
k
ELECTRICAL CHARACTERISTICS (continued)
(V
CC
= +4.75V to +5.5V for MAX82_L, V
CC
= +4.5V to +5.5V for MAX82_M, V
CC
= +3.15V to +3.6V for MAX82_T, V
CC
= +3V
to +3.6V for MAX82_S, V
CC
= +2.7V to +3.6V for MAX82_R, V
CC
= +2.38V to +2.75V for MAX82_Z, V
CC
= +2.25V to +2.75V for
MAX82_Y, T
A
= T
MIN
to T
MAX
, T
A
= -40
C to +85C (SC70), T
A
= -40
C to +125C (SOT23), unless otherwise noted. Typical values
are at T
A
= +25
C.) (Note 1)
MAX823/MAX824/MAX825
5-Pin Microprocessor Supervisory Circuits With
Watchdog Timer and Manual Reset
_______________________________________________________________________________________
5
__________________________________________Typical Operating Characteristics
MAX823_, V
CC
= +5V, T
A
= +25C, unless otherwise noted.)
1
3
2
6
5
4
8
7
9
-40
20
40
-20
0
60
80
100 120
MAX823/4/5 toc01
TEMPERATURE (
C)
SUPPLY CURRENT (
A)
V
CC
SUPPLY CURRENT
vs. TEMPERATURE
MAX823L
(SC70 ONLY)
MAX824Y
MAX825R
250
150
-40
-20
40
100
RESET TIMEOUT PERIOD
vs. TEMPERATURE
170
160
180
230
240
MAX823/4/5 toc02
TEMPERATURE (
C)
RESET TIMEOUT PERIOD (ms)
0
20
80
60
210
220
190
200
30
0
-40
-20
40
100
RESET COMPARATOR PROPAGATION DELAY
vs. TEMPERATURE
5
25
MAX823/4/5 toc03
TEMPERATURE (
C)
PROPAGATION DELAY (
s)
0
20
80
60
20
10
15
V
CC
FALLING
2.0
1.0
-40
-20
40
100
WATCHDOG TIMEOUT PERIOD
vs. TEMPERATURE
1.2
1.1
1.3
1.8
1.9
MAX823/4/5 toc04
TEMPERATURE (
C)
WATCHDOG TIMEOUT PERIOD (s)
0
20
80
60
1.6
1.7
1.4
1.5
1.06
0.94
0.96
0.98
1.00
1.02
1.04
-40
-20
40
100
NORMALIZED RESET THRESHOLD
VOLTAGE vs. TEMPERATURE
MAX823/4/5 toc05
TEMPERATURE (
C)
NORMALIZED RESET THRESHOLD (V)
0
20
80
60
0
10
5
20
15
30
25
35
45
40
50
0
40 60 80
20
100 120 140
180
160
200
MAX823/4/5 toc06
RESET THRESHOLD OVERDRIVE (mV), V
RST
- V
CC
TRANSIENT DURATION (
s)
(SC70 ONLY)
MAXIMUM V
CC
TRANSIENT DURATION
vs. RESET THRESHOLD OVERDRIVE
RESET OCCURS
ABOVE CURVE
MAX82_Y
MAX82_R
MAX82_L
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