Analog Devices ADM1232ARW, ADM1232ARM, ADM1232AN Datasheet

Microprocessor

a

FEATURES
Superior Upgrade for MAX1232 and Dallas DS1232
Low Power Consumption (500 mA max)
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
APPLICATIONS

Microprocessor Systems
Portable Equipment
Computers
Controllers
Intelligent Instruments
Automotive Systems
Protection Against Damage Caused by mP Failure

V

TOLERANCE

PB RESET

TD

GND

Supervisory Circuit

ADM1232

FUNCTIONAL BLOCK DIAGRAM

5%/10%

CC

TOLERANCE

SELECT

DEBOUNCE

WATCHDOG

TIMEBASE

SELECT

VREF

ADM1232

RESET

GENERATOR

WATCHDOG

TIMER

RESET

RESET

GENERAL DESCRIPTION

The ADM1232 is a superior, pin-compatible upgrade for the
MAX1232 and the DS1232LP and DS1232. The Analog
Devices ADM1232 is a microprocessor monitoring circuit that
can monitor:

1. Microprocessor Supply Voltage.

2. Whether a Microprocessor has locked-up.

3. An External Interrupt.
The ADM1232 is available in four different packages:

1. The ADM1232ARM in an 8-lead microSOIC (RM-8).

2. The ADM1232AN in an 8-lead PDIP (N-8).

3. The ADM1232ARW in a 16-lead wide SOIC (R-16).

4. The ADM1232ARN is an 8-lead narrow SOIC (R-8).

+5V

10kV

MICROPROCESSOR

I/O

RESET

ADM1232

GND TD

+5V

ADM1232

ADM1232

STROBE

TOLERANCE

TOLERANCE

RESET

STROBE

RESET

Figure 1. Typical Supply Monitoring Application

REV. B

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
which may result from its use. No license is granted by implication or
otherwise under any patent or patent rights of Analog Devices.

One Technology Way, P.O. Box 9106, Norwood, MA 02062-9106, U.S.A.
Tel: [phone] World Wide Web Site: http://www.analog.com
Fax: [phone] © Analog Devices, Inc., 1997

ADM1232–SPECIFICATIONS

P

arameter Min Typ Max Units Test Conditions/Comments

(VCC = Full Operating Range, TA = T

TEMPERATURE –40 +85 °CT

MIN

to T

unless otherwise noted)

MAX

= T

MIN

to T

MAX

A

POWER SUPPLY

Voltage 4.5 5.0 5.5 V
Current 20 50 µAV

, VIH = CMOS Levels

IL

200 500 µAVIL, VIH = TTL Levels

STROBE AND PB RESET INPUTS

Input High Level 2.0 V

+ 0.3 V

CC

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 When V

Is at 4.5 V–5.5 V

CC

RESET, RESET –8 –12 mA When VCC Is at 4.5 V–5.5 V

OUTPUT VOLTAGE

RESET/RESET V

– 0.5 VCC – 0.1 V While sourcing less than 500 µA, RESET remains

CC

within 0.5 V of V

on power-down until V

CC

CC

drops below 2.0 V. While sinking less than
500 µA, RESET remains within 0.5 V of GND
on power-down until V

drops below 2.0 V.

CC

RESET/RESET High Level 0.4 V
RESET/RESET Low Level 2.4 V

1 V OPERATION

RESET Output Voltage V

– 0.1 V While Sourcing Less than 50 µA

CC

RESET Output Voltage 0.1 V While Sinking Less than 50 µA

TRIP POINT

V

CC

5% 4.5 4.62 4.74 V TOLERANCE = GND
10% 4.25 4.37 4.49 V TOLERANCE = V

CC

CAPACITANCE

Input (STROBE, TOLERANCE) 5 pF T
Output (RESET, RESET)7pFT

= +25°C

A

= +25°C

A

PB RESET

Time 20 ms PB RESET Must Be Held Low for a Minimum
Delay 1 4 20 ms of 20 ms to Guarantee a Reset

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 = V

V

CC

Fall Time 10 µ
Rise Time 0 µ

FAIL DETECT TO RESET OUTPUT DELAY

V

CC

S
S

RESET AND RESET Are Logically Correct 50 µs After V

CC

Guaranteed by Design
Guaranteed by Design

Falls Below the Set Tolerance Voltage

CC

(Figure 5)

250 610 1000 ms After VCC Rises Above the Set Tolerance Voltage

Specifications subject to change without notice.

–2–

REV. B