General Description

The MAX6821–MAX6825 are low-voltage microprocessor

(µP) supervisory circuits that combine voltage monitor-

ing, watchdog timer, and manual reset input functions in

a 5-pin SOT23 package. Microprocessor supervisory cir-

cuits significantly improve system reliability and accura-

cy compared to separate ICs or discrete components.

These devices assert a reset signal whenever the moni-

tored voltage drops below its preset threshold, keeping it

above the threshold. In addition, a watchdog timer moni-

tors against code execution errors. A debounced manual

reset is also available. The MAX6821–MAX6825 monitor

voltages from +1.8V to +5.0V. These outputs are guaran-

Nine preprogrammed reset threshold voltages are

available (see Threshold Suffix Guide). The MAX6821,

MAX6822, and MAX6823 all have a manual reset input

and a watchdog timer. The MAX6821 has push-pull

RESET, the MAX6822 has open-drain RESET, and the

MAX6823 has push-pull RESET. The MAX6824 has a

watchdog timer and both push-pull RESET and push-

pull RESET. The MAX6825 has a manual reset input

and both push-pull RESET and push-pull RESET. The

Selector Guide explains the functions offered in this

series of parts.

________________________Applications

Features

o Monitors +1.8V, +2.5V, +3.0V, +3.3V, +5.0V

Supplies

o 140ms (min) Reset Timeout Delay

o 1.6s Watchdog Timeout Period

(MAX6821/MAX6822/MAX6823/MAX6824)

o Manual Reset Input

(MAX6821/MAX6822/MAX6823/MAX6825)

o Three Reset Output Options

Push-Pull RESET

Push-Pull RESET

Open-Drain RESET

o No External Components

o Small 5-Pin SOT23 Packages

Low-Voltage SOT23 µP Supervisors with

Manual Reset and Watchdog Timer

________________________________________________________________ Maxim Integrated Products

1

GND

WDI

MR

15

RESET(RESET)

(RESET) MAX6821 ONLY

MAX6821

MAX6822

MAX6823

SOT23-5

TOP VIEW

2

34

Pin Configurations

19-1868; Rev 1; 1/01

Ordering Information

Threshold Suffix Guide

*Insert the desired suffix letter (from the table below) into the blank

to complete the part number.

Note: Bold indicates standard versions. Samples are typically

available for standard versions only. All parts require a 2.5k

minimum order increment. Contact factory for availability.

TEMP. RANGE

PIN-PACKAGE

MAX6821_UK-T

-40

°C to +125°C

5 SOT23-5

MAX6822_UK-T

-40

°C to +125°C

5 SOT23-5

MAX6823_UK-T

-40

°C to +125°C

5 SOT23-5

MAX6824_UK-T

-40

°C to +125°C

5 SOT23-5

MAX6825_UK-T

-40

°C to +125°C

5 SOT23-5

SUFFIX

RESET

THRESHOLD (V)

L

4.63

M

4.38

T

3.08

S

2.93

R

2.63

Z

2.32

Y

2.19

W

1.67

V

1.58

Typical Operating Circuit appears at end of data sheet.

Pin Configurations continued at end of data sheet.

Selector Guide appears at end of data sheet.

Set-Top Boxes

Computers and

Controllers

Embedded Controllers

Intelligent Instruments

Automotive Systems

Critical µP Monitoring

Portable/Battery-

Powered Equipment

For price, delivery, and to place orders, please contact Maxim Distribution at 1-888-629-4642,

or visit Maxim’s website at www.maxim-ic.com.