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_______________General Description

The MAX6301–MAX6304* low-power microprocessor

(µP) supervisory circuits provide maximum adjustability

for reset and watchdog functions. The reset threshold

can be adjusted to any voltage above 1.22V, using

external resistors. In addition, the reset and watchdog

timeout periods are adjustable using external capaci-

tors. A watchdog select pin extends the watchdog time-

out period to 500x. The reset function features immunity

to power-supply transients.

These four devices differ only in the structure of their reset

outputs (see the

Selector Guide

). The MAX6301–MAX6304

are available in the space-saving 8-pin µMAX

package,

as well as 8-pin PDIP and SO packages.

Applications

Medical Equipment Embedded Controllers

Intelligent Instruments Critical µP Monitoring

Portable Equipment Set-Top Boxes

Battery-Powered Computers

Computers/Controllers

____________________________Features

o Adjustable Reset Threshold

o Adjustable Reset Timeout

o Adjustable Watchdog Timeout

o 500x Watchdog Timeout Multiplier

o 4µA Supply Current

o RESET or RESET Output Options

o Push-Pull or Open-Drain Output Options

o Guaranteed RESET Asserted At or Above

= 1V (MAX6301/MAX6303)

o Power-Supply Transient Immunity

o Watchdog Function can be Disabled

o PDIP/SO/µMAX Packages Available

MAX6301–MAX6304

+5V, Low-Power µP Supervisory Circuits

with Adjustable Reset/Watchdog

________________________________________________________________

Maxim Integrated Products

0.1µF

MAX6301

MAX6302

MAX6303

MAX6304

RESET IN

SWT

SRT

GND

SWT

WDI

WDS

RESET

µP

I/O

RESET

(RESET)

MAX6301

ONLY

MAX6302

ONLY

WDS = 0 FOR NORMAL MODE

WDS = 1 FOR EXTENDED MODE

( ) ARE FOR MAX6302/MAX6304.

Pin Configuration

RESET (RESET)

WDI

WDS

RESET IN

GND

SRT

SWT

MAX6301

MAX6302

MAX6303

MAX6304

DIP/SO/µMAX

TOP VIEW

( ) ARE FOR MAX6302/MAX6304.

Typical Operating Circuit

19-1078; Rev 4; 9/10

Ordering Information

Ordering Information continued at end of data sheet.

For pricing, delivery, and ordering information, please contact Maxim Direct at 1-888-629-4642,

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

Selector Guide

FEATURE MAX6301 MAX6302 MAX6303 MAX6304

Acti ve-Low

Reset

√ — √ —

Acti ve-H i g h

Reset

— √ — √

Op en- D rai n

Reset Outp ut

√√——

P ush- P ul l

Reset Outp ut

—— √√

P i n- P ackag e

8- PD IP /S O/

µM AX

8- PD IP /S O/

µM AX

8- PD IP /S O/

µM AX

8- PD IP /S O/

µM AX

µMAX is a registered trademark of Maxim Integrated Products, Inc.

PART TEMP RANGE PIN-PACKAGE

MAX6301CPA 0°C to +70°C 8 PDIP

MAX6301CSA 0°C to +70°C 8 SO

MAX6301CUA 0°C to +70°C 8 µMAX

MAX6301EPA -40°C to +85°C 8 PDIP

MAX6301ESA -40°C to +85°C 8 SO

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

compliant packaging. Specify lead-free by adding the “+

”

symbol at the end of the part number when ordering.

Summary of content (12 pages)

PAGE 1
9-1078; Rev 4; 9/10 +5V, Low-Power µP Supervisory Circuits with Adjustable Reset/Watchdog The MAX6301–MAX6304* low-power microprocessor (µP) supervisory circuits provide maximum adjustability for reset and watchdog functions. The reset threshold can be adjusted to any voltage above 1.22V, using external resistors. In addition, the reset and watchdog timeout periods are adjustable using external capacitors. A watchdog select pin extends the watchdog timeout period to 500x.
PAGE 2
MAX6301–MAX6304 +5V, Low-Power µP Supervisory Circuits with Adjustable Reset/Watchdog ABSOLUTE MAXIMUM RATINGS VCC ....................................................................................-0.3V to +7.0V RESET IN, SWT, SRT ..................................-0.3V to (VCC + 0.3V) WDI, WDS..............................................................-0.3V to +7.0V RESET, RESET MAX6301… .......................................................-0.3V to +7.0V MAX6302/MAX6303/MAX6304...............-0.
PAGE 3
+5V, Low-Power µP Supervisory Circuits with Adjustable Reset/Watchdog (VCC = +2V to +5.5V, TA = TMIN to TMAX, unless otherwise noted. Typical values are at VCC = +5V and TA = +25°C.) PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS WATCHDOG TIMER VIH WDI, WDS Input Threshold 0.7 x VCC WDI Pulse Width tWP VCC = 4.5V to 5.5V 30 VCC = 2V to 4.5V 60 WDI, WDS Leakage Current Extended mode disabled WDI Sink/Source Current (Note 4) Extended mode enabled Watchdog Timeout Period (Note 3) V 0.
PAGE 4
____________________________Typical Operating Characteristics (continued) (CSWT = CSRT = 1500pF, TA = +25°C, unless otherwise noted.) RESET AND NORMAL-MODE WATCHDOG TIMEOUT PERIOD vs. TEMPERATURE 3.6 4.05 3.4 3.2 4.00 3.95 3.0 3.90 2.8 3.85 2.6 3.80 2.0 2.5 3.0 3.5 4.0 TRANSIENT DURATION (µs) 4.10 tRP/tWD (ms) 3.8 1.5 VCC = 5.0V 4.15 4.5 5.0 5.5 6.0 -40 -20 0 20 40 60 80 0 100 200 400 600 3.75 3.50 VCC = 2.0V MAX6301-4 toc08 MAX6301-4 toc07 VCC = 5.0V 1.224 1.222 1.220 1.
PAGE 5
+5V, Low-Power µP Supervisory Circuits with Adjustable Reset/Watchdog PIN NAME 1 RESET IN 2 GND Ground 3 SRT Set Reset-Timeout Input. Connect a capacitor between this input and ground to select the reset timeout period (tRP). Determine the period as follows: tRP = 2.67 x CSRT, with CSRT in pF and tRP in µs (see the Typical Operating Circuit). 4 SWT Set Watchdog-Timeout Input. Connect a capacitor between this input and ground to select the basic watchdog timeout period (tWD).
PAGE 6
MAX6301–MAX6304 +5V, Low-Power µP Supervisory Circuits with Adjustable Reset/Watchdog Detailed Description VIN Reset Function/Output The reset output is typically connected to the reset input of a µP. A µP’s reset input starts or restarts the µP in a known state. The MAX6301–MAX6304 µP supervisory circuits provide the reset logic to prevent code-execution errors during power-up, power-down, and brownout conditions (see the Typical Operating Circuit).
PAGE 7
+5V, Low-Power µP Supervisory Circuits with Adjustable Reset/Watchdog MAX6301–MAX6304 VCC tWD WDI tRP 0V VCC RESET 0V NORMAL MODE (WDS = GND) Figure 2a. Watchdog Timing Diagram, WDS = GND VCC tWD x 500 WDI tRP 0V VCC RESET 0V EXTENDED MODE (WDS = VCC) Figure 2b. Watchdog Timing Diagram, WDS = VCC watchdog counter. When WDI is left unconnected, the watchdog timer is cleared by this internal driver just before the timeout period is reached (the internal driver pulls WDI high at about 94% of tWD).
PAGE 8
MAX6301–MAX6304 +5V, Low-Power µP Supervisory Circuits with Adjustable Reset/Watchdog VIN VCC VCC VCC 80C51 R1 MAX6302 RESET IN VCC VCC VCC RST RESET R2 MAX6301 MAX6302 MAX6303 MAX6304 0.1µF * WDI I/O WDS I/O I/O GND GND VRST = 1.22 (R1R2+ R2) *THREE-STATE LEAKAGE MUST BE < 10µA. Figure 4. Monitoring Votlages Other than VCC Figure 5. Wake-Up Timer with CSRT in pF and tRP in µs. CSRT must be a low-leakage (< 10nA) type capacitor. Ceramic is recommended.
PAGE 9
+5V, Low-Power µP Supervisory Circuits with Adjustable Reset/Watchdog TO RESET GENERATOR VCC VCC µP MAX6301 WDI WATCHDOG TIMER VCC 0.1µF GND 4.7kΩ WDS RESET RESET Figure 7. Interfacing to µPs with Bidirectional Reset I/O Pins Interfacing to µPs with Bidirectional Reset Pins Since RESET is open-drain, the MAX6301 interfaces easily with µPs that have bidirectional reset pins, such as the Motorola 68HC11 (Figure 7).
PAGE 10
MAX6301–MAX6304 +5V, Low-Power µP Supervisory Circuits with Adjustable Reset/Watchdog VCC VCC MAX6303 MAX6304 VCC 100kΩ VCC 0.1µF 0.1µF RESET RESET 100kΩ GND Figure 9. Ensuring RESET Valid to VCC = 0V In those applications where RESET must be valid down to 0V, adding a pulldown resistor between RESET and ground sinks any stray leakage currents, holding RESET low (Figure 9).
PAGE 11
+5V, Low-Power µP Supervisory Circuits with Adjustable Reset/Watchdog PIN-PACKAGE 8 PDIP Chip Information PROCESS: CMOS PART MAX6302CPA TEMP RANGE 0°C to +70°C MAX6302CSA 0°C to +70°C 8 SO MAX6302CUA 0°C to +70°C 8 µMAX MAX6302EPA -40°C to +85°C 8 PDIP MAX6302ESA -40°C to +85°C 8 SO MAX6303CPA 0°C to +70°C 8 PDIP MAX6303CSA 0°C to +70°C 8 SO MAX6303CUA 0°C to +70°C 8 µMAX PACKAGE TYPE PACKAGE CODE OUTLINE NO. LAND PATTERN NO.
PAGE 12
MAX6301–MAX6304 +5V, Low-Power µP Supervisory Circuits with Adjustable Reset/Watchdog Revision History REVISION NUMBER REVISION DATE DESCRIPTION 0 7/96 Initial release 1 12/05 Added lead-free notation. 2 3/07 Updated Typical Operating Circuit. 3 3/09 Updated Pin Description, Applications Information, Figure 3, and Package Information. 4 9/10 Updated Absolute Maximum Ratings, correct part number.