Microprocessor
Supervisory Circuit
ADM1232
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
V
CC
TOLERANCE
FUNCTIONAL BLOCK DIAGRAM
RESET
GENERATOR
5%/10%
TOLERANCE
SELECT
RESET
VREF
PB RESET
TD
GND
DEBOUNCE
WATCHDOG
TIME-BASE
SELECT
RESET
WATCHDOG
TIMER
STROBE
07522-001
APPLICATIONS
Microprocessor systems
Portable equipment
Computers
Controllers
Intelligent instruments
Automotive systems
ADM1232
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
5V
5V
10kΩ
ADM1232
STROBE
RESET
GND
TD TOLERANCE
MICROPROCESSOR
I/O
RESET
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).
Figure 2. Typical Supply Monitoring Application
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.
07522-002
ADM1232
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
Rev. C | Page 2 of
12
ADM1232
SPECIFICATIONS
V
CC
= full operating range, T
A
= T
MIN
to T
MAX
, unless otherwise noted.
Table 1.
Parameter
TEMPERATURE
POWER SUPPLY
Voltage
Current
STROBE AND PB RESET INPUTS
Input High Level
Input Low Level
INPUT LEAKAGE CURRENT
(STROBE, TOLERANCE)
TD
OUTPUT CURRENT
RESET
RESET/RESET
OUTPUT VOLTAGE
RESET/RESET
Min
−40
4.5
Typ
Max
+85
5.5
50
500
V
CC
+ 0.3
+0.8
+1.0
1.6
8
−8
V
CC
− 0.5
10
−12
V
CC
− 0.1
Unit
°C
V
μA
μA
V
V
μA
μA
mA
mA
V
V
CC
is at 4.5 V to 5.5 V.
V
CC
is at 4.5 V to 5.5 V.
When sourcing less than 500 μA, RESET remains within
0.5 V of V
CC
on power-down until V
CC
drops below 2.0 V.
When sinking less than 500 μA, RESET remains within
0.5 V of GND on power-down until V
CC
drops below 2.0 V.
Test Conditions/Comments
T
A
= T
MIN
to T
MAX
.
5.0
20
200
V
IL
, V
IH
= CMOS levels.
V
IL
, V
IH
= TTL levels.
2.0
−0.3
−1.0
RESET/RESET High Level
RESET/RESET Low Level
1 V OPERATION
RESET Output Voltage
RESET Output Voltage
V
CC
TRIP POINT
5%
10%
CAPACITANCE
Input (STROBE, TOLERANCE)
Output (RESET, RESET)
PB RESET
Time
Delay
RESET ACTIVE TIME
STROBE
Pulse Width
Timeout Period
0.4
2.4
V
CC
− 0.1
0.1
4.5
4.25
4.62
4.37
4.74
4.49
5
7
20
1
250
70
62.5
250
500
10
0
4
610
20
1000
V
V
V
V
V
V
pF
pF
ms
ms
ms
ns
ms
ms
ms
μs
μs
When sourcing less than 50 μA.
When sinking less than 50 μA.
TOLERANCE = GND.
TOLERANCE = V
CC
.
T
A
= 25°C.
T
A
= 25°C.
PB RESET must be held low for a minimum of 20 ms to
guarantee a reset.
150
600
1200
250
1000
2000
TD = 0 V.
TD = floating.
TD = V
CC
.
Guaranteed by design.
Guaranteed by design.
RESET and RESET are logically correct.
After V
CC
falls below the set tolerance voltage (see Figure 9).
After V
CC
rises above the set tolerance voltage.
V
CC
Fall Time
Rise Time
V
CC
FAIL DETECT TO RESET
OUTPUT DELAY
250
610
50
1000
μs
ms
Rev. C | Page 3 of
12
ADM1232
ABSOLUTE MAXIMUM RATINGS
T
A
= 25°C unless otherwise noted.
Table 2.
Parameter
V
CC
Logic Inputs
Storage Temperature Range
Lead Temperature (Soldering, 10 sec)
Vapor Phase (60 sec)
Infrared (15 sec)
Power Dissipation
N-8
1
RW-16, RM-8
2
R-8
2
1
2
THERMAL RESISTANCE
Rating
5.5 V
−0.3 V to V
CC
+ 0.3 V
−65°C to +150°C
300°C
215°C
220°C
1000 mW
900 mW
900 μW
θ
JA
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
8-Lead PDIP (N-8)
16-Lead SOIC_W (RW-16)
8-Lead MSOP (RM-8)
8-Lead SOIC_N (R-8)
θ
JA
100
73
206
153
Unit
°C/W
°C/W
°C/W
°C/W
ESD CAUTION
Derate by 13.5 mW/°C above 25°C.
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.
Rev. C | Page 4 of
12
ADM1232
PIN CONFIGURATIONS AND FUNCTION DESCRIPTIONS
NC
1
PB RESET
2
NC
3
TD
4
NC
5
TOLERANCE
6
NC
7
GND
8
16
NC
15
V
CC
13
STROBE
TOP VIEW
(Not to Scale)
12
NC
11
RESET
10
NC
07522-003
ADM1232
14
NC
9
RESET
NC = NO CONNECT
Figure 3. RW-16 Pin Configuration
PB RESET
1
TD
2
TOLERANCE
3
GND
4
8
ADM1232
TOP VIEW
(Not to Scale)
V
CC
STROBE
RESET
07522-004
07522-005
7
6
5
RESET
Figure 4. RM-8 Pin Configuration
PB RESET
1
TD
2
TOLERANCE
3
GND
4
8
ADM1232
TOP VIEW
(Not to Scale)
V
CC
STROBE
RESET
RESET
7
6
5
Figure 5. N-8 and R-8 Pin Configuration
Table 4. Pin Function Descriptions
Pin No.
N-8, R-8,
RM-8
RW-16
1, 3, 5, 7,
10, 12,
14, 16
2
1
4
2
Mnemonic
NC
Description
No Connection.
PB RESET
TD
6
8
9
3
4
5
TOLERANCE
GND
RESET
11
13
15
6
7
8
RESET
STROBE
V
CC
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.
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 Specifications section, Figure 8, and the STROBE Timeout Selection section.
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 V
CC
for 10% and to GND for 5%.
0 V Ground Reference for All Signals.
Active High Logic Output. This pin is asserted when any of the following events occurs:
V
CC
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.
Inverse of RESET. This pin has an open-drain output.
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.
Power Supply Input, 5 V.
Rev. C | Page 5 of
12
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