Datasheet

ManualsBrandsMAXIM INTEGRATED ManualsPMICsPMIC - system monitor Reset/power-on reset SOT 23 5

________________General Description

The MAX823/MAX824/MAX825* microprocessor (µP)

supervisory circuits combine reset output, watchdog,

and manual reset input functions in 5-pin SOT23 and

SC70 packages. They significantly improve system relia-

bility and accuracy compared to separate ICs or discrete

components. The MAX823/MAX824/MAX825 are specifi-

cally designed to ignore fast transients on V

Seven preprogrammed reset threshold voltages are

available (see Reset Threshold Table). All three devices

have an active-low reset output, which is guaranteed to

be in the correct state for V

down to 1V. The MAX823

also offers a watchdog input and manual reset input.

The MAX824 offers a watchdog input and a comple-

mentary active-high reset. The MAX825 offers a manual

reset input and a complementary active-high reset. The

Selector Guide explains the functions offered in this

series of parts.

________________________Applications

Computers and Controllers

Embedded Controllers

Intelligent Instruments

Automotive Systems

Critical µP Monitoring

Portable/Battery-Powered Equipment

Features

♦ Precision Monitoring of +2.5V, +3V, +3.3V, and

+5V Power Supplies

♦ Operating Current: 6µA (MAX823L/M) (SC70)

2µA (MAX825T/S/R/Z/Y) (SC70)

♦ Fully Specified Over Temperature

♦ 140ms min Power-On Reset

♦ Guaranteed RESET Valid to V

= 1V

♦ Power-Supply Transient Immunity

♦ Watchdog Timer with 1.6s Timeout

(MAX823/MAX824)

♦ Manual Reset Input (MAX823/MAX825)

♦ No External Components

MAX823/MAX824/MAX825

5-Pin Microprocessor Supervisory Circuits With

Watchdog Timer and Manual Reset

________________________________________________________________ Maxim Integrated Products 1

GND

WDI

MAX823

SOT23/SC70

TOP VIEW

RESET

GND

WDI

RESET

MAX824

SOT23/SC70

RESET

GND

RESET

MAX825

SOT23/SC70

RESET

______________________Selector Guide

19-0487; Rev 5; 12/05

†Insert the desired suffix letter (from the Reset Threshold table) into

the blank to complete the part number. All devices are available in

tape-and-reel only. There is a 2500 piece minimum order increment.

Devices are available in both leaded and lead-free packaging.

Specify lead-free by replacing “-T” with “+T” when ordering.

MAX823

Active-Low Reset

✔

Active-High Reset —

FUNCTION

Watchdog Input

✔

MAX824

✔

MAX825

✔

—

Manual Reset Input

✔

—

✔

SUFFIX

RESET

THRESHOLD (V)

L 4.63

M 4.38

T 3.08

S 2.93

R 2.63

Typical Operating Circuit appears at end of data sheet.

Marking Information appears at end of data sheet.

Ordering Information

PART

†

TEMP. RANGE PIN-PACKAGE

MAX823_EXK-T

-40°C to +85°C

5 SC70-5

MAX823_EUK-T

-40°C to +125°C

5 SOT23-5

MAX824_EXK-T

-40°C to +85°C

5 SC70-5

Ordering Information continued at end of data sheet.

Reset Threshold Table

Z (SC70 only) 2.32

Y (SC70 only) 2.19

Pin Configurations

*Pg

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.

Summary of content (10 pages)

PAGE 1
9-0487; Rev 5; 12/05 5-Pin Microprocessor Supervisory Circuits With Watchdog Timer and Manual Reset The MAX823/MAX824/MAX825* microprocessor (µP) supervisory circuits combine reset output, watchdog, and manual reset input functions in 5-pin SOT23 and SC70 packages. They significantly improve system reliability and accuracy compared to separate ICs or discrete components. The MAX823/MAX824/MAX825 are specifically designed to ignore fast transients on VCC.
PAGE 2
MAX823/MAX824/MAX825 5-Pin Microprocessor Supervisory Circuits With Watchdog Timer and Manual Reset ABSOLUTE MAXIMUM RATINGS VCC ........................................................................-0.3V to +6.0V All Other Pins..............................................-0.3V to (VCC + 0.3V) Input Current, All Pins Except RESET and RESET..............20mA Output Current, RESET, RESET ..........................................20mA Continuous Power Dissipation (TA = +70°C) 5-Pin SC70 (derate 3.
PAGE 3
5-Pin Microprocessor Supervisory Circuits With Watchdog Timer and Manual Reset (VCC = +4.75V to +5.5V for MAX82_L, VCC = +4.5V to +5.5V for MAX82_M, VCC = +3.15V to +3.6V for MAX82_T, VCC = +3V to +3.6V for MAX82_S, VCC = +2.7V to +3.6V for MAX82_R, VCC = +2.38V to +2.75V for MAX82_Z, VCC = +2.25V to +2.75V for MAX82_Y, TA = TMIN to TMAX, TA = -40°C to +85°C (SC70), TA = -40°C to +125°C (SOT23), unless otherwise noted. Typical values are at TA = +25°C.
PAGE 4
MAX823/MAX824/MAX825 5-Pin Microprocessor Supervisory Circuits With Watchdog Timer and Manual Reset ELECTRICAL CHARACTERISTICS (continued) (VCC = +4.75V to +5.5V for MAX82_L, VCC = +4.5V to +5.5V for MAX82_M, VCC = +3.15V to +3.6V for MAX82_T, VCC = +3V to +3.6V for MAX82_S, VCC = +2.7V to +3.6V for MAX82_R, VCC = +2.38V to +2.75V for MAX82_Z, VCC = +2.25V to +2.75V for MAX82_Y, TA = TMIN to TMAX, TA = -40°C to +85°C (SC70), TA = -40°C to +125°C (SOT23), unless otherwise noted.
PAGE 5
-Pin Microprocessor Supervisory Circuits With Watchdog Timer and Manual Reset RESET TIMEOUT PERIOD vs. TEMPERATURE MAX823L 7 6 5 MAX824Y 4 3 MAX825R 2 220 210 200 190 180 170 VCC FALLING 25 20 15 10 5 160 150 -40 -20 0 20 40 60 80 0 -40 100 120 -20 0 20 40 60 80 100 -20 0 20 40 60 80 100 TEMPERATURE (°C) TEMPERATURE (°C) WATCHDOG TIMEOUT PERIOD vs. TEMPERATURE NORMALIZED RESET THRESHOLD VOLTAGE vs. TEMPERATURE MAXIMUM VCC TRANSIENT DURATION vs.
PAGE 6
5-Pin Microprocessor Supervisory Circuits With Watchdog Timer and Manual Reset MAX823/MAX824/MAX825 Pin Description MAX823 PIN MAX824 MAX825 NAME FUNCTION Active-Low Reset Output. Pulses low for 200ms when triggered, and remains low whenever VCC is below the reset threshold or when MR is a logic low. It remains low for 200ms after one of the following occurs: VCC rises above the reset threshold, the watchdog triggers a reset, or MR goes low to high.
PAGE 7
5-Pin Microprocessor Supervisory Circuits With Watchdog Timer and Manual Reset Watchdog Input (MAX823/MAX824) A microprocessor’s (µP’s) reset input starts the µP in a known state. The MAX823/MAX824/MAX825 µP supervisory circuits assert a reset to prevent code-execution errors during power-up, power-down, and brownout conditions. RESET is guaranteed to be a logic low for VCC down to 1V.
PAGE 8
MAX823/MAX824/MAX825 5-Pin Microprocessor Supervisory Circuits With Watchdog Timer and Manual Reset Interfacing to µPs with Bidirectional Reset Pins The RESET output maximum pullup current is 800µA for L/M versions (400µA for T/S/R/Z/Y versions). This allows µPs with bidirectional resets, such as the 68HC11, to force RESET low when the MAX823/MAX824/MAX825 are pulling RESET high (Figure 4).
PAGE 9
5-Pin Microprocessor Supervisory Circuits With Watchdog Timer and Manual Reset ____________________Chip Information TRANSISTOR COUNT: 607 VCC VCC PROCESS TECHNOLOGY: BiCMOS VCC RESET RESET MAX823 µP WDI I/O MR MANUAL RESET GND GND Ordering Information (continued) PART† TEMP.
PAGE 10
Package Information (The package drawing(s) in this data sheet may not reflect the most current specifications. For the latest package outline information, go to www.maxim-ic.com/packages.) SOT-23 5L .EPS MAX823/MAX824/MAX825 5-Pin Microprocessor Supervisory Circuits With Watchdog Timer and Manual Reset PACKAGE OUTLINE, SOT-23, 5L 21-0057 E 1 1 Maxim cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in a Maxim product. No circuit patent licenses are implied.