Datasheet

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General Description

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.

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

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

ditions (5% or 10% supply tolerances can be selected

digitally). Also featured is a debounced manual reset

input that forces the reset outputs to their active states

for a minimum of 250ms. A digitally programmable watch-

dog timer monitors software execution and can be pro-

grammed for timeout settings of 150ms, 600ms, or 1.2s.

The MAX1232 requires no external components.

Applications

● Computers

● Controllers

● Intelligent Instruments

● Critical μP Power Monitoring

Features

● Consumes 1/10th the Power of the DS1232

● Precision Voltage Monitor—Adjustable +4.5V or

+4.75V

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

● No External Components

● Adjustable Watchdog Timer—150ms, 600ms, or 1.2s

● Debounced Manual Reset Input for External Override

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

Packages

19-3899; Rev 2; 9/14

Ordering Information continued at end of data sheet.

*Contact factory for dice specifications.

Note: Devices in PDIP and SO packages are available in both

leaded(Pb) and lead(Pb)-free packaging. Specify lead(Pb)-free by

adding the “+” symbol at the end of the part number when order-

ing. 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

5%/10%

TOLERANCE

SELECT

RESET

GENERATOR

DEBOUNCE

REF

TOL

PB RST

RST

STTD

GND

WATCHDOG

TIMEBASE

SELECT

WATCHDOG

TIMER

MAX1232

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

MAX1232 Microprocessor Monitor

Typical Operating Circuit

Pin Congurations

Ordering Information

Summary of content (8 pages)

PAGE 1
MAX1232 Microprocessor Monitor General Description 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 Range 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)......
PAGE 3
MAX1232 Microprocessor Monitor AC Electrical Characteristics (VCC = +5V ±10%, TA = TMIN to TMAX, unless otherwise noted.) PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS tPB Figure 3 20 PBRST Delay tPBD Figure 3 1 4 20 ms Reset Active Time tRST 250 610 1000 ms PBRST (Note 5) ST Pulse Width tST ST Timeout Period tTD Figure 4 ms 75 ns Figure 4, TD pin = 0V 62.
PAGE 4
MAX1232 Microprocessor Monitor Detailed Description Watchdog Timer 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
MAX1232 Microprocessor Monitor 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) +4.25V (10% TRIP POINT) +4.5V (10% TRIP POINT) VCC tRPD RST tRPU RST VOH RST VOL VOH RST VOL VCC SLEW RATE = 1.66mV/sec (0.5V/300µsec) Figure 7. VCC Detect Reset Output Delay (Power-Down) www.maximintegrated.com Figure 8.
PAGE 7
MAX1232 Microprocessor Monitor Chip Topography Ordering Information PB RST VCC TD 0.099" (2.51 mm) PART TEMP RANGE PIN-PACKAGE MAX1232CWE 0°C to +70°C MAX1232EPA -40°C to +85°C 8 PDIP MAX1232ESA -40°C to +85°C 8 SO MAX1232EWE -40°C to +85°C 16 Wide SO MAX1232MJA -55°C to +125°C 8 CERDIP 16 Wide SO *Contact factory for dice specifications. Note: Devices in PDIP and SO packages are available in both leaded(Pb) and lead(Pb)-free packaging.
PAGE 8
MAX1232 Microprocessor Monitor Revision History REVISION NUMBER REVISION DATE 1 11/05 Added lead-free information to the Ordering Information table 1, 6 2 9/14 Removed reference to automotive systems in the Applications 1 DESCRIPTION PAGES CHANGED For pricing, delivery, and ordering information, please contact Maxim Direct at 1-888-629-4642, or visit Maxim Integrated’s website at www.maximintegrated.com.