Datasheet

ManualsBrandsMAXIM INTEGRATED ManualsPMICsPMIC - system monitor Reset/power-on reset PDIP 8

General Description

The MAX1232 microprocessor (µP) supervisory circuit

provides µP housekeeping and power-supply supervi-

sion functions while consuming only 1/10th the power of

the DS1232. The MAX1232 enhances circuit reliability

in µP systems by monitoring the power supply, monitor-

ing the software execution, and providing a debounced

manual reset input. The MAX1232 is a plug-in upgrade

of the Dallas DS1232.

A reset pulse of at least 250ms duration is supplied on

power-up, power-down, and low-voltage brownout

conditions (5% or 10% supply tolerances can be

selected digitally). Also featured is a debounced man-

ual reset input that forces the reset outputs to their

active states for a minimum of 250ms. A digitally pro-

grammable watchdog timer monitors software execu-

tion and can be programmed for timeout settings of

150ms, 600ms, or 1.2s. The MAX1232 requires no

external components.

Applications

Computers

Controllers

Intelligent Instruments

Automotive Systems

Critical µP Power Monitoring

Features

o Consumes 1/10th the Power of the DS1232

o Precision Voltage Monitor—Adjustable +4.5V

or +4.75V

o Power-OK/Reset Pulse Width—250ms Min

o No External Components

o Adjustable Watchdog Timer—150ms, 600ms,

or 1.2s

o Debounced Manual Reset Input for External

Override

o Available in 8-Pin PDIP/SO and 16-Pin Wide SO

Packages

MAX1232

Microprocessor Monitor

________________________________________________________________

Maxim Integrated Products

RST

RSTGND

STTD

TOL

PB RST

DIP/SO

TOP VIEW

MAX1232

N.C.

RST

N.C.

RST

MAX1232

WIDE SO

PB RST

N.C.

TOL

N.C.

GND

Pin Configurations

Ordering Information

5%/10%

TOLERANCE

SELECT

RESET

GENERATOR

DEBOUNCE

REF

TOL

PB RST

RST

STTD

GND

WATCHDOG

TIMEBASE

SELECT

WATCHDOG

TIMER

MAX1232

Typical Operating Circuit

19-3899; Rev 1; 11/05

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.

Ordering Information continued on last page.

Contact factory for dice specifications.

Devices in PDIP and SO packages are available in both leaded

and lead-free packaging. Specify lead free by adding the

symbol at the end of the part number when ordering. Lead free

not available for CERDIP package.

PART TEMP RANGE PIN-PACKAGE

MAX1232C/D 0°C to +70°C Dice*

MAX1232CPA 0°C to +70°C 8 PDIP

MAX1232CSA 0°C to +70°C 8 SO

Summary of content (6 pages)

PAGE 1
9-3899; Rev 1; 11/05 Microprocessor Monitor The MAX1232 microprocessor (µP) supervisory circuit provides µP housekeeping and power-supply supervision functions while consuming only 1/10th the power of the DS1232. The MAX1232 enhances circuit reliability in µP systems by monitoring the power supply, monitoring the software execution, and providing a debounced manual reset input. The MAX1232 is a plug-in upgrade of the Dallas DS1232.
PAGE 2
MAX1232 Microprocessor Monitor ABSOLUTE MAXIMUM RATINGS Voltage on Any Pin (with respect to GND)……………-1V to +7V Operating Temperature Range C Suffix ………………………………………………0°C to +70°C E Suffix.……………………………………………-40°C to +85°C M Suffix .…………………………………………-55°C to +125°C Storage Temperature Range……………………-65°C to +160°C Lead Temperature (soldering, 10s)………………………+300°C Stresses beyond those listed under “Absolute Maximum Ratings” may cause permanent damage to the device.
PAGE 3
Microprocessor Monitor MAX1232 AC Electrical Characteristics (VCC = +5V ±10%, TA = TMIN to TMAX) PARAMETER SYMBOL PBRST (Note 5) CONDITIONS tPB Figure 3 PBRST Delay tPBD Figure 3 Reset Active Time tRST ST Pulse Width tST ST Timeout Period tTD MIN TYP MAX 20 Figure 4 UNITS ms 1 4 20 ms 250 610 1000 ms 75 ns Figure 4, TD pin = 0V 62.
PAGE 4
MAX1232 Microprocessor Monitor Detailed Description Power Monitor A voltage detector monitors VCC and holds the reset outputs (RST and RST) in their active states whenever VCC is below the selected 5% or 10% tolerance (4.62V or 4.37V, typically). To select the 5% level, connect TOL to ground. To select the 10% level, connect TOL to VCC.
PAGE 5
Microprocessor Monitor MAX1232 tST ST tPB tPBD PB RST tTD VIH VIL tRST RST NOTE: tSD IS THE MAXIMUM ELAPSED TIME BETWEEN ST HIGH-TO-LOW TRANSITIONS (ST IS ACTIVATED BY FALLING EDGES ONLY) WHICH WILL KEEP THE WATCHDOG TIMER FROM FORCING THE RESET OUTPUTS ACTIVE FOR A TIME OF tRST. tTD IS A FUNCTION OF THE VOLTAGE AT THE TD PIN, AS TABULATED BELOW. RST Figure 3. Pushbutton Reset. The debounced PBRST input ignores input pulses less than 1ms and is guaranteed to recognize pulses of 20ms or greater.
PAGE 6
MAX1232 Microprocessor Monitor VCC +4.5V (5% TRIP POINT) +4.75V (5% TRIP POINT) +4.5V (10% TRIP POINT) +4.25V (10% TRIP POINT) VCC tRPD tRPU RST RST VOH VOH VOL RST VOL RST VCC SLEW RATE = 1.66mV/µsec (0.5V/300µsec) Figure 7. VCC Detect Reset Output Delay (Power-Down) Chip Topography PB RST Figure 8. VCC Detect Reset Output Delay (Power-Up) Ordering Information (continued) PART VCC TD 0.099" (2.