Microprocessor
Supervisory Circuit
ADM1232
Rev. C
Information furnished by Analog Devices is believed to be accurate and reliable. However, no
responsibility is assumed by Analog Devices for its use, nor for any infringements of patents or other
rights of third parties that may result from its use. Specifications subject to change without notice. No
license is granted by implication or otherwise under any patent or patent rights of Analog Devices.
Trademarks and registered trademarks are the property of their respective owners.
One Technology Way, P.O. Box 9106, Norwood, MA 02062-9106, U.S.A.
Tel: 781.329.4700 www.analog.com
Fax: 781.461.3113 ©1997–2008 Analog Devices, Inc. All rights reserved.
FEATURES
Pin-compatible with MAX1232 and Dallas DS1232
Adjustable precision voltage monitor with 4.5 V and
4.75 V options
Adjustable strobe monitor with 150 ms, 600 ms, or
1.2 sec options
No external components
Specified from −40°C to +85°C
APPLICATIONS
Microprocessor systems
Portable equipment
Computers
Controllers
Intelligent instruments
Automotive systems
FUNCTIONAL BLOCK DIAGRAM
VCC
T
OLERANCE
PB RESET
TD
5%/10%
TOLERANCE
SELECT
RESET
GENERATOR
RESET
GND
DEBOUNCE
VREF
RESET
WATCHDOG
TIMER
WATCHDOG
TIME-BASE
SELECT
STROBE
7522-001
ADM1232
0
Figure 1.
GENERAL DESCRIPTION
The ADM1232 is pin-compatible with the MAX1232, DS1232LP,
and DS1232. The Analog Devices, Inc., ADM1232 is a micro-
processor monitoring circuit that can monitor the following:
• Microprocessor supply voltage
• Whether a microprocessor has locked up
• External interrupts
The ADM1232 is available in four packages: an 8-lead MSOP
(RM-8), an 8-lead PDIP (N-8), a 16-lead wide SOIC (RW-16),
and an 8-lead narrow SOIC (R-8).
MICROPROCESSOR
GND TD TOLERANCE
RESET
STROBE
RESET
I/O
ADM1232
5
V
5
V
10kΩ
07522-002
Figure 2. Typical Supply Monitoring Application
ADM1232
Rev. C | Page 2 of 12
TABLE OF CONTENTS
Features .............................................................................................. 1
Applications ....................................................................................... 1
Functional Block Diagram .............................................................. 1
General Description ......................................................................... 1
Revision History ............................................................................... 2
Specifications ..................................................................................... 3
Absolute Maximum Ratings ............................................................ 4
Thermal Resistance ...................................................................... 4
ESD Caution .................................................................................. 4
Pin Configurations and Function Descriptions ............................5
Circuit Information ...........................................................................6
PB RESET .......................................................................................6
STROBE Timeout Selection .........................................................6
Tolerance ........................................................................................6
RESET and RESET Outputs .........................................................6
Outline Dimensions ..........................................................................7
Ordering Guide .............................................................................9
REVISION HISTORY
12/08—Rev. B to Rev. C
Updated Format .................................................................. Universal
Changes to Table 2 ............................................................................ 4
Added Thermal Resistance Section ............................................... 4
Updated Outline Dimensions ......................................................... 7
Changes to Ordering Guide ............................................................ 9
12/97—Rev. A to Rev. B
Changes to Specifications Section .................................................. 2
x/97—Rev. 0 to Rev. A
Changes to Specifications Section .................................................. 2
7/97—Revision 0: Initial Version
ADM1232
Rev. C | Page 3 of 12
SPECIFICATIONS
VCC = full operating range, TA = TMIN to TMAX, unless otherwise noted.
Table 1.
Parameter Min Typ Max Unit Test Conditions/Comments
TEMPERATURE −40 +85 °C TA = TMIN to TMAX.
POWER SUPPLY
Voltage 4.5 5.0 5.5 V
Current 20 50 μA VIL, VIH = CMOS levels.
200 500 μA VIL, VIH = TTL levels.
STROBE AND PB RESET INPUTS
Input High Level 2.0 VCC + 0.3 V
Input Low Level −0.3 +0.8 V
INPUT LEAKAGE CURRENT
(STROBE, TOLERANCE) −1.0 +1.0 μA
TD 1.6 μA
OUTPUT CURRENT
RESET 8 10 mA VCC is at 4.5 V to 5.5 V.
RESET/RESET −8 −12 mA VCC is at 4.5 V to 5.5 V.
OUTPUT VOLTAGE
RESET/RESET VCC − 0.5 VCC − 0.1 V When sourcing less than 500 μA, RESET remains within
0.5 V of VCC on power-down until VCC drops below 2.0 V.
When sinking less than 500 μA, RESET remains within
0.5 V of GND on power-down until VCC drops below 2.0 V.
RESET/RESET High Level 0.4 V
RESET/RESET Low Level 2.4 V
1 V OPERATION
RESET Output Voltage VCC − 0.1 V When sourcing less than 50 μA.
RESET Output Voltage 0.1 V When sinking less than 50 μA.
VCC TRIP POINT
5% 4.5 4.62 4.74 V TOLERANCE = GND.
10% 4.25 4.37 4.49 V TOLERANCE = VCC.
CAPACITANCE
Input (STROBE, TOLERANCE) 5 pF T
A = 25°C.
Output (RESET, RESET) 7 pF T
A = 25°C.
PB RESET
Time 20 ms
PB RESET must be held low for a minimum of 20 ms to
guarantee a reset.
Delay 1 4 20 ms
RESET ACTIVE TIME 250 610 1000 ms
STROBE
Pulse Width 70 ns
Timeout Period 62.5 150 250 ms TD = 0 V.
250 600 1000 ms TD = floating.
500 1200 2000 ms TD = VCC.
VCC
Fall Time 10 μs Guaranteed by design.
Rise Time 0 μs Guaranteed by design.
VCC FAIL DETECT TO RESET
OUTPUT DELAY
RESET and RESET are logically correct.
50 μs After VCC falls below the set tolerance voltage (see Figure 9).
250 610 1000 ms After VCC rises above the set tolerance voltage.
ADM1232
Rev. C | Page 4 of 12
ABSOLUTE MAXIMUM RATINGS
THERMAL RESISTANCE
TA = 25°C unless otherwise noted.
Table 2.
Parameter Rating
VCC 5.5 V
Logic Inputs −0.3 V to VCC + 0.3 V
Storage Temperature Range −65°C to +150°C
Lead Temperature (Soldering, 10 sec) 300°C
Vapor Phase (60 sec) 215°C
Infrared (15 sec) 220°C
Power Dissipation
N-81 1000 mW
RW-16, RM-82 900 mW
R-82 900 μW
θJA is specified for the worst-case conditions, that is, a device
soldered in a circuit board for surface-mount packages.
Table 3. Thermal Resistance
Package Type θJA Unit
8-Lead PDIP (N-8) 100 °C/W
16-Lead SOIC_W (RW-16) 73 °C/W
8-Lead MSOP (RM-8) 206 °C/W
8-Lead SOIC_N (R-8) 153 °C/W
ESD CAUTION
1 Derate by 13.5 mW/°C above 25°C.
2 Derate by 12 mW/°C above 25°C.
Stresses above those listed under Absolute Maximum Ratings
may cause permanent damage to the device. This is a stress
rating only; functional operation of the device at these or any
other conditions above those indicated in the operational
section of this specification is not implied. Exposure to absolute
maximum rating conditions for extended periods may affect
device reliability.
ADM1232
Rev. C | Page 5 of 12
PIN CONFIGURATIONS AND FUNCTION DESCRIPTIONS
NC
1
PB RESET
2
NC
3
TD
4
NC
16
V
CC
15
NC
14
STROBE
13
NC
5
NC
12
TOLERANCE
6
RESET
11
NC
7
NC
10
GND
8
RESET
9
NC = NO CONNECT
ADM1232
TOP VIEW
(Not to Scale)
07522-003
ADM1232
TOP VIEW
(Not to Scale)
Figure 3. RW-16 Pin Configuration
PB RESET
1
V
CC
8
TD
2
STROBE
7
TOLERANCE
3
RESET
6
GND
4
RESET
5
07522-004
Figure 4. RM-8 Pin Configuration
PB RESET
1
TD
2
TOLERANCE
3
GND
4
V
CC
8
STROBE
7
RESET
6
ADM1232
TOP VIEW
(Not to Scale) RESET
5
07522-005
Figure 5. N-8 and R-8 Pin Configuration
Table 4. Pin Function Descriptions
Pin No.
Mnemonic Description
RW-16
N-8, R-8,
RM-8
1, 3, 5, 7,
10, 12,
14, 16
NC No Connection.
2 1 PB RESET Push-Button Reset Input. This debounced input ignores pulses of less than 1 ms and is
guaranteed to respond to pulses greater than 20 ms.
4 2 TD Time Delay Set. This input allows the user to select the maximum amount of time that the
ADM1232 allows the STROBE input to remain inactive—that is, STROBE is not receiving any
high-to-low transitions—without forcing the ADM1232 to generate a RESET pulse.
See the section, , and the Specifications Figure 8 STROBE Timeout Selection section.
6 3 TOLERANCE
Tolerance Input. This input determines how much the supply voltage is allowed to decrease (as a
percentage) before a RESET is asserted. Connect this pin to VCC for 10% and to GND for 5%.
8 4 GND 0 V Ground Reference for All Signals.
9 5 RESET
Active High Logic Output. This pin is asserted when any of the following events occurs:
VCC decreases below the amount specified by the TOLERANCE input; when PB RESET is forced low;
if there are no high-to-low transitions within the limits set by TD at STROBE; and during power-up.
11 6 RESET Inverse of RESET. This pin has an open-drain output.
13 7 STROBE The STROBE input is used to monitor the activity of a microprocessor. If there are no high-to-low
transitions within the time specified by TD, a reset is asserted.
15 8 VCC Power Supply Input, 5 V.
ADM1232
Rev. C | Page 6 of 12
CIRCUIT INFORMATION
PB RESET STROBE TIMEOUT SELECTION
The PB RESET input makes it possible to manually reset a
system using either a standard push-button switch or a logic
low input. An internal debounce circuit provides glitch
immunity when used with a switch, reducing the effects of
glitches on the line. The debounce circuit is guaranteed to cause
the ADM1232 to assert a reset if PB RESET is brought low for
more than 20 ms and is guaranteed to ignore low inputs of less
than 1 ms.
TD (time delay) set is used to set the strobe timeout period. The
strobe timeout period is the maximum time between high-to-
low transitions that STROBE accepts before a reset is asserted
(see ). The strobe timeout settings are listed in . Figure 8 Table 5
Table 5. Strobe Timeout Settings
Condition Min Typ Max Unit
TD = 0 V 62.5 150 250 ms
TD = Floating 250 600 1000 ms
TD = VCC 500 1200 2000 ms
MICROPROCESSOR
GND TOLERANCE
RESET
STROBE
RESETPB RESET
I/O
ADM1232
V
CC
V
CC
TD
STROBE
PULSE WIDTH
STROBE TIMEOUT PERIOD
STROBE
07522-008
07522-0
RESET
06
Figure 8. STROBE Parameters
Figure 6. Typical Push-Button Reset Application
RESET
PB RESET
V
IL
RESET ACTIVE
TIME
PB RESET
DELAY
PB RESET TIME
V
IH
07
5V
V
CC
RESET
5V 4.5V (5% TRIP POINT)
RESET OUTPUT DELAY
HEN V
CC
IS FALLING
RESET OUTPUT DELAY
WHEN V
CC
IS RISINGW
4.25V (10% TRIP POINT)
RESET
07522-009
Figure 9. Reset Output Delay
07522-0
TOLERANCE
Figure 7. PB RESET
The TOLERANCE input is used to determine the level at which
VCC can vary below 5 V without the ADM1232 asserting a reset.
Connecting TOLERANCE to GND selects a −5% tolerance level
and causes the ADM1232 to generate a reset if VCC falls below
4.75 V. If TOLERANCE is connected to VCC, a −10% tolerance
level is selected, which causes the ADM1232 to generate a reset
if VCC falls below 4.5 V. See the parameters for the VCC trip point
in the Specifications section for more information.
RESET AND RESET OUTPUTS
RESET is capable of sourcing and sinking current, whereas
RESET is an open-drain MOSFET that sinks current only.
Therefore, it is necessary to pull this output high.
ADM1232
Rev. C | Page 7 of 12
CONTROLLING DIMENSIONS ARE IN MILLIMETERS; INCH DIMENSIONS
(IN PARENTHESES) ARE ROUNDED-OFF MILLIMETER EQUIVALENTS FOR
REFERENCE ONLY AND ARE NOT APPROPRIATE FOR USE IN DESIGN.
COMPLIANT TO JEDEC STANDARDS MS-013- AA
032707-B
10.50 (0.4134)
10.10 (0.3976)
OUTLINE DIMENSIONS
0.30 (0.0118)
0.10 (0.0039)
2.65 (0.1043)
2.35 (0.0925)
10.65 (0.4193)
10.00 (0.3937)
7.60 (0.2992)
7.40 (0.2913)
0.75 (0.0295)
0.25 (0.0098)
45°
1.27 (0.0500)
0.40 (0.0157)
COPLANARITY
0.10 0.33 (0.0130)
0.20 (0.0079)
0.51 (0.0201)
0.31 (0.0122)
SEATING
PLANE
8°
0°
16 9
8
1
1.27 (0.0500)
BSC
Figure 10. 16-Lead Standard Small Outline Package [SOIC_W]
Wide Body
(RW-16)
Dimensions shown in millimeters and (inches)
0.80
0.60
0.40
8°
0°
4
8
1
5
PIN 1
0.65 BSC
SEATING
PLANE
0.38
0.22
1.10 MAX
3.20
3.00
2.80
COMPLIANT TO JEDEC STANDARDS MO-187-AA
COPLANARITY
0.10
0.23
0.08
3.20
3.00
2.80
5.15
4.90
4.65
0.15
0.00
0.95
0.85
0.75
Figure 11. 8-Lead Mini Small Outline Package [MSOP]
(RM-8)
Dimensions shown in millimeters
ADM1232
Rev. C | Page 8 of 12
COMPLIANT TO JEDEC STANDARDS MS-001
CONTROLLING DIMENSIONS ARE IN INCHES; MILLIMETER DIMENSIONS
(IN PARENTHESES) ARE ROUNDED-OFF INCH EQUIVALENTS FOR
REFERENCE ONLY AND ARE NOT APPROPRIATE FOR USE IN DESIGN.
CORNER LEADS MAY BE CONFIGURED AS WHOLE OR HALF LEADS.
070606-A
0.022 (0.56)
0.018 (0.46)
0.014 (0.36)
SEATING
PLANE
0.015
(0.38)
MIN
0.210 (5.33)
MAX
0.150 (3.81)
0.130 (3.30)
0.115 (2.92)
0.070 (1.78)
0.060 (1.52)
0.045 (1.14)
8
14
5
0.280 (7.11)
0.250 (6.35)
0.240 (6.10)
0.100 (2.54)
BSC
0.400 (10.16)
0.365 (9.27)
0.355 (9.02)
0.060 (1.52)
MAX
0.430 (10.92)
MAX
0.014 (0.36)
0.010 (0.25)
0.008 (0.20)
0.325 (8.26)
0.310 (7.87)
0.300 (7.62)
0.195 (4.95)
0.130 (3.30)
0.115 (2.92)
0.015 (0.38)
GAUGE
PLANE
0.005 (0.13)
MIN
Figure 12. 8-Lead Plastic Dual In-Line Package [PDIP]
Narrow Body
(N-8)
Dimensions shown in inches and (millimeters)
CONTROLLING DIMENSIONS ARE IN MILLIMETERS; INCH DIMENSIONS
(IN PARENTHESES) ARE ROUNDED-OFF MILLIMETER EQUIVALENTS FOR
REFERENCE ONLY AND ARE NOT APPROPRIATE FOR USE IN DESIGN.
COMPLIANT TO JEDEC STANDARDS MS-012-A A
012407-A
0.25 (0.0098)
0.17 (0.0067)
1.27 (0.0500)
0.40 (0.0157)
0.50 (0.0196)
0.25 (0.0099) 45°
8°
0°
1.75 (0.0688)
1.35 (0.0532)
SEATING
PLANE
0.25 (0.0098)
0.10 (0.0040)
4
1
85
5.00 (0.1968)
4.80 (0.1890)
4.00 (0.1574)
3.80 (0.1497)
1.27 (0.0500)
BSC
6.20 (0.2441)
5.80 (0.2284)
0.51 (0.0201)
0.31 (0.0122)
COPLANARITY
0.10
Figure 13. 8-Lead Standard Small Outline Package [SOIC_N]
Narrow Body
(R-8)
Dimensions shown in millimeters and (inches)
ADM1232
Rev. C | Page 9 of 12
ORDERING GUIDE
Model
Temperature
Range Package Description
Package
Options Branding
ADM1232ARM −40°C to +85°C 8-Lead Mini Small Outline Package [MSOP] RM-8 M2A
ADM1232ARM-REEL −40°C to +85°C 8-Lead Mini Small Outline Package [MSOP] RM-8 M2A
ADM1232ARM-REEL7 −40°C to +85°C 8-Lead Mini Small Outline Package [MSOP] RM-8 M2A
ADM1232ARMZ1−40°C to +85°C 8-Lead Mini Small Outline Package [MSOP] RM-8 M4W
ADM1232ARMZ-REEL1
−40°C to +85°C 8-Lead Mini Small Outline Package [MSOP] RM-8 M4W
ADM1232ARMZ-REEL71
−40°C to +85°C 8-Lead Mini Small Outline Package [MSOP] RM-8 M4W
ADM1232AN −40°C to +85°C 8-Lead Plastic Dual In-Line Package [PDIP] N-8
ADM1232ANZ1
−40°C to +85°C 8-Lead Plastic Dual In-Line Package [PDIP] N-8
ADM1232ARW −40°C to +85°C 16-Lead Standard Small Outline Package [SOIC_W], Wide Body RW-16
ADM1232ARW-REEL −40°C to +85°C 16-Lead Standard Small Outline Package [SOIC_W], Wide Body RW-16
ADM1232ARW-REEL7 −40°C to +85°C 16-Lead Standard Small Outline Package [SOIC_W], Wide Body RW-16
ADM1232ARWZ1
−40°C to +85°C 16-Lead Standard Small Outline Package [SOIC_W], Wide Body RW-16
ADM1232ARWZ-REEL1
−40°C to +85°C 16-Lead Standard Small Outline Package [SOIC_W], Wide Body RW-16
ADM1232ARWZ-REEL71
−40°C to +85°C 16-Lead Standard Small Outline Package [SOIC_W], Wide Body RW-16
ADM1232ARN −40°C to +85°C 8-Lead Standard Small Outline Package [SOIC_N] R-8
ADM1232ARN-REEL −40°C to +85°C 8-Lead Standard Small Outline Package [SOIC_N] R-8
ADM1232ARN-REEL7 −40°C to +85°C 8-Lead Standard Small Outline Package [SOIC_N] R-8
ADM1232ARNZ1
−40°C to +85°C 8-Lead Standard Small Outline Package [SOIC_N] R-8
ADM1232ARNZ-REEL1
−40°C to +85°C 8-Lead Standard Small Outline Package [SOIC_N] R-8
ADM1232ARNZ-REEL71
−40°C to +85°C 8-Lead Standard Small Outline Package [SOIC_N] R-8
1 Z = RoHS Compliant Part.
ADM1232
Rev. C | Page 10 of 12
NOTES
ADM1232
Rev. C | Page 11 of 12
NOTES
ADM1232
Rev. C | Page 12 of 12
NOTES
©1997–2008 Analog Devices, Inc. All rights reserved. Trademarks and
registered trademarks are the property of their respective owners.
D07522-0-12/08(C)
