Datasheet

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

● Set-Top Boxes

● Computers and Con-

trollers

● Embedded Controllers

● Intelligent Instruments

● Critical µP Monitoring

● Portable/Battery-

Powered Equipment

General Description

The MAX6821–MAX6825 are low-voltage microproces-

sor (µP) supervisory circuits that combine voltage mon-

itoring, watchdog timer, and manual reset input func-

tions in a 5-pin SOT23 package. Microprocessor super-

visory circuits significantly improve system reliability and

accuracy compared to separate ICs or discrete compo-

nents. These devices assert a reset signal whenever the

monitored voltage drops below its preset threshold, keep-

ing it asserted for a minimum timeout period after V

rises

above the threshold. In addition, a watchdog timer monitors

against code execution errors. A debounced manual reset

is also available. The MAX6821–MAX6825 monitor voltag-

es from +1.8V to +5.0V. These outputs are guaranteed to

be in the correct state for V

down to +1.0V.

Nine preprogrammed reset threshold voltages are

available (see the 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.

Features

● Monitors +1.8V, +2.5V, +3.0V, +3.3V, +5.0V Supplies

● 140ms (min) Reset Timeout Delay

● 1.6s Watchdog Timeout Period (MAX6821/MAX6822/

MAX6823/MAX6824)

● Manual Reset Input (MAX6821/MAX6822/MAX6823/

MAX6825)

● Three Reset Output Options

Push-Pull RESET

Open-Drain RESET

● Guaranteed Reset Valid to V

= +1.0V

● Immune to Short Negative V

Transients

● No External Components

● Small 5-Pin SOT23 Packages

Applications

19-1868; Rev 3; 7/14

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.

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

blank to complete the part number

Devices are available in both leaded and lead(Pb)-free packag-

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

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

PART* 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

GND

WDIMR

1 5 V

RESET(RESET)

(RESET) MAX6821 ONLY

MAX6821

MAX6822

MAX6823

SOT23-5

TOP VIEW

3 4

MAX6821/MAX6825 Low-Voltage SOT23 µP Supervisors

with Manual Reset and Watchdog Timer

Selector Guide appears at end of data sheet.

Threshold Sufx Guide

Ordering Information

Typical Operating Circuit appears at end of data sheet.

Pin Configurations continued at end of data sheet.

Pin Congurations

Summary of content (9 pages)

PAGE 1
MAX6821/MAX6825 Low-Voltage SOT23 µP Supervisors with Manual Reset and Watchdog Timer General Description The MAX6821–MAX6825 are low-voltage microprocessor (µP) supervisory circuits that combine voltage monitoring, watchdog timer, and manual reset input functions in a 5-pin SOT23 package. Microprocessor supervisory circuits significantly improve system reliability and accuracy compared to separate ICs or discrete components.
PAGE 2
MAX6821/MAX6825 Low-Voltage SOT23 µP Supervisors with Manual Reset and Watchdog Timer Absolute Maximum Ratings VCC to GND..........................................................-0.3V to +6.0V Open-Drain RESET...............................................-0.3V to +6.0V Push-Pull RESET, RESET, MR, WDI........ -0.3V to (VCC + 0.3V) Input Current (VCC).............................................................20mA Output Current (RESET, RESET).......................................
PAGE 3
MAX6821/MAX6825 Low-Voltage SOT23 µP Supervisors with Manual Reset and Watchdog Timer Electrical Characteristics (continued) (VCC = +4.5V to +5.5V for MAX682_L/M, VCC = +2.7V to +3.6V for MAX682_T/S/R, VCC = +2.1V to +2.75V for MAX682_Z/Y, VCC = +1.53V to +2.0V for MAX682_W/V, TA = -40°C to +125°C, unless otherwise specified. Typical values are at TA = +25°C.
PAGE 4
MAX6821/MAX6825 Low-Voltage SOT23 µP Supervisors with Manual Reset and Watchdog Timer Typical Operating Characteristics (TA = +25°C, unless otherwise noted.) 10 9 5 VCC = +1.8V, V VERSION -40 -20 0 20 40 60 180 170 20 15 10 5 -40 -20 0 20 40 60 0 80 100 120 -40 -20 0 20 40 60 80 100 120 TEMPERATURE (°C) TEMPERATURE (°C) WATCHDOG TIMEOUT PERIOD vs. TEMPERATURE NORMALIZED RESET THRESHOLD DELAY vs. TEMPERATURE MAXIMUM VCC TRANSIENT DURATION vs. RESET THRESHOLD OVERDRIVE 1.06 1.
PAGE 5
MAX6821/MAX6825 Low-Voltage SOT23 µP Supervisors with Manual Reset and Watchdog Timer Pin Description PIN NUMBERS PIN MAX6821 MAX6822 MAX6823 MAX6824 MAX6825 NAME 1 1 1 2 3 2 3 2 1 1 RESET Active-Low Open-Drain or Push-Pull Reset Output. RESET changes from high to low when the VCC input drops below the selected reset threshold, MR is pulled low, or the watchdog triggers a reset.
PAGE 6
MAX6821/MAX6825 Low-Voltage SOT23 µP Supervisors with Manual Reset and Watchdog Timer VCC MAX6821– MAX6825 RESET (MAX6822–MAX6825) RESET GENERATOR RESET (MAX6821/MAX6824/ MAX6825) VCC 1.26V MR (MAX6821–MAX6823, MAX6825) WDI (MAX6821–MAX6824) WATCHDOG TRANSITION DETECTOR WATCHDOG TIMER GND Figure 1. Functional Diagram Disable the watchdog function by leaving WDI unconnected or by three-stating the driver connected to WDI.
PAGE 7
MAX6821/MAX6825 VCC RESET* Low-Voltage SOT23 µP Supervisors with Manual Reset and Watchdog Timer tRST VCC VCC MAX6822 tRP tWD RESET tRP WDI RESET µP RESET GENERATOR GND GND *RESET IS THE INVERSE OF RESET. Figure 3. Watchdog Timing Relationship Figure 4. Interfacing open-Drain RESET to µPs with Bidirectional Reset I/O Resets are issued to the µP during power-up, power-down, and brownout conditions.
PAGE 8
MAX6821/MAX6825 Low-Voltage SOT23 µP Supervisors with Manual Reset and Watchdog Timer Selector Guide FUNCTION ACTIVE-LOW RESET ACTIVE-HIGH RESET OPEN-DRAIN RESET WATCHDOG INPUT MANUAL RESET INPUT MAX6821 — ✔ — ✔ ✔ MAX6822 — — ✔ ✔ ✔ MAX6823 ✔ — — ✔ ✔ MAX6824 ✔ ✔ — ✔ — MAX6825 ✔ ✔ — — ✔ Pin Configurations (continued) TOP VIEW RESET 1 GND 2 5 VCC MAX6824 RESET 3 RESET 1 GND 2 4 WDI TRANSISTOR COUNT: 750 PROCESS: BiCMOS 4 MR SOT23-5 Package Information For th
PAGE 9
MAX6821/MAX6825 Low-Voltage SOT23 µP Supervisors with Manual Reset and Watchdog Timer Revision History REVISION NUMBER REVISION DATE 3 7/14 PAGES CHANGED DESCRIPTION No /V OPNs; removed automotive reference from Applications section 1 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.