Datasheet

ManualsBrandsMAXIM INTEGRATED ManualsPMICsPMIC - system monitor Reset/power-on reset uMAX 8

MAX705–MAX708/MAX813L

Low-Cost, µP Supervisory Circuits

________________________________________________________________ Maxim Integrated Products 1

TOP VIEW

WDO

RESET (RESET)

WDI

PFO

PFI

GND

DIP/SO

MAX705

MAX706

MAX813L

RESET

N.C.

PFO

PFI

GND

DIP/SO

MAX707

MAX708

( ) ARE FOR MAX813L ONLY.

Pin Configurations continued at end of data sheet.

_________________Pin Configurations

PFI

PFO

WDO

RESET

UNREGULATED DC

PUSHBUTTON

SWITCH

PFI

I/O LINE

INTERRUPT

µP

MAX705

MAX706

MAX813L

MAX667

+5V DC LINEAR

REGULATOR

RESET

NMI

__________Typical Operating Circuit

19-4334; Rev. 7; 12/05

_______________General Description

The MAX705-MAX708/MAX813L microprocessor (µP)

supervisory circuits reduce the complexity and number

of components required to monitor power-supply and

battery functions in µP systems. These devices signifi-

cantly improve system reliability and accuracy com-

pared to separate ICs or discrete components.

The MAX705/MAX706/MAX813L provide four functions:

1) A reset output during power-up, power-down, and

brownout conditions.

2) An independent watchdog output that goes low if

the watchdog input has not been toggled within 1.6

seconds.

3) A 1.25V threshold detector for power-fail warning,

low-battery detection, or for monitoring a power sup-

ply other than +5V.

4) An active-low manual-reset input.

The MAX707/MAX708 are the same as the MAX705/

MAX706, except an active-high reset is substituted for

the watchdog timer. The MAX813L is the same as the

MAX705, except RESET is provided instead of RESET.

Two supply-voltage monitor levels are available: The

MAX705/MAX707/MAX813L generate a reset pulse when

the supply voltage drops below 4.65V, while the

MAX706/MAX708 generate a reset pulse below 4.40V.

All four parts are available in 8-pin DIP, SO and µMAX

packages.

_______________________Applications

Computers

Controllers

Intelligent Instruments

Automotive Systems

Critical µP Power Monitoring

___________________________Features

♦ µMAX Package: Smallest 8-Pin SO

♦ Guaranteed RESET Valid at V

= 1V

♦ Precision Supply-Voltage Monitor

4.65V in MAX705/MAX707/MAX813L

4.40V in MAX706/MAX708

♦ 200ms Reset Pulse Width

♦ Debounced TTL/CMOS-Compatible

Manual-Reset Input

♦ Independent Watchdog Timer—1.6sec Timeout

(MAX705/MAX706)

♦ Active-High Reset Output

(MAX707/MAX708/MAX813L)

♦ Voltage Monitor for Power-Fail or Low-Battery

Warning

______________Ordering Information

PART TEMP RANGE PIN-PACKAGE

MAX705CPA

8 Plastic DIP

MAX705CSA 0°C to +70°C 8 SO

MAX705C/D 0°C to +70°C Dice*

Ordering Information continued at end of data sheet.

* Dice are specified at T

= +25°C.

**Contact factory for availability and processing to MIL-STD-883.

Devices in PDIP, SO and µMAX packages are available in both

leaded and lead-free packaging. Specify lead free by adding

the + symbol at the end of the part number when ordering.

Lead free not available for CERDIP package.

0°C to +70°C

MAX705CUA 0°C to +70°C 8µMAX

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 (11 pages)

PAGE 1
9-4334; Rev. 7; 12/05 Low-Cost, µP Supervisory Circuits The MAX705-MAX708/MAX813L microprocessor (µP) supervisory circuits reduce the complexity and number of components required to monitor power-supply and battery functions in µP systems. These devices significantly improve system reliability and accuracy compared to separate ICs or discrete components. The MAX705/MAX706/MAX813L provide four functions: 1) A reset output during power-up, power-down, and brownout conditions.
PAGE 2
MAX705–MAX708/MAX813L Low-Cost, µP Supervisory Circuits ABSOLUTE MAXIMUM RATINGS Terminal Voltage (with respect to GND) VCC . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . -0.3V to 6.0V All Other Inputs (Note 1) . . . . . . . . . . . . . . . -0.3V to (VCC + 0.3V) Input Current VCC . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20mA GND . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
PAGE 3
Low-Cost, µP Supervisory Circuits (VCC = 4.75V to 5.5V for MAX705/MAX707/MAX813L, VCC = 4.5V to 5.5V for MAX706/MAX708, TA = TMIN to TMAX, unless otherwise noted.) PARAMETER SYMBOL MR Pull-Up Current CONDITIONS MR = 0V MR Pulse Width tMR MR to Reset Out Delay (Note 2) PFI Input Threshold MAX UNITS 250 600 µA ns 0.8 2.0 tMD 250 VCC = 5V PFI Input Current PFO Output Voltage TYP 100 150 Low High MR Input Threshold MIN ISOURCE = 800µA ISINK = 3.2mA V ns 1.20 1.25 1.30 V -25.00 0.
PAGE 4
__________________________________________Typical Operating Characteristics MAX705/MAX707 RESET OUTPUT VOLTAGE vs. SUPPLY VOLTAGE MAX705/MAX707 RESET RESPONSE TIME POWER-FAIL COMPARATOR DE-ASSERTION RESPONSE TIME +5V VCC +4V TA = +25°C VCC GND RESET 330pF 1V/div RESET RESET VCC 2k PFO 30pF 1k +1.25V +3V 1V/div +5V VCC VCC = +5V TA = +25°C PFO +5V 0V +5V PFI +5V VCC TA = +25°C 1V/div RESET VCC RESET GND 10k 0V RESET 30pF PFI +1.30V +1.
PAGE 5
Low-Cost, µP Supervisory Circuits PIN MAX705/MAX706 MAX707/MAX708 DIP/SO DIP/SO µMAX µMAX MAX813L DIP/SO NAME FUNCTION µMAX 1 3 1 3 1 3 MR Manual-Reset Input triggers a reset pulse when pulled below 0.8V. This active-low input has an internal 250µA pull-up current. It can be driven from a TTL or CMOS logic line as well as shorted to ground with a switch.
PAGE 6
MAX705–MAX708/MAX813L Low-Cost, µP Supervisory Circuits WDI 6 WATCHDOG TRANSITION DETECTOR WATCHDOG TIMER VCC VCC WDO 1 MR 7 RESET GENERATOR 2 8 VCC RESET (RESET) VCC 1 RESET GENERATOR 2 4.65V* PFI PFI 5 7 RESET MAX707 MAX708 4.65V* MAX705 MAX706 MAX813L 4 RESET 250µA TIMEBASE FOR RESET AND WATCHDOG 250µA MR 8 4 5 PFO PFO 1.25V 1.25V * 4.40V FOR MAX7O6. ( ) ARE FOR MAX813L ONLY. 3 3 GND GND * 4.40V FOR MAX7O6. Figure 1. MAX705/MAX706/MAX813L Block Diagram Figure 2.
PAGE 7
Low-Cost, µP Supervisory Circuits tWP WDI tWD tWD tWD 0V When VCC falls below 1V, the MAX705-MAX708 RESET output no longer sinks current—it becomes an open circuit. High-impedance CMOS logic inputs can drift to undetermined voltages if left undriven. If a pull-down resistor is added to the RESET pin as shown in Figure 5, any stray charge or leakage currents will be drained to ground, holding RESET low. Resistor value (R1) is not critical.
PAGE 8
MAX705–MAX708/MAX813L Low-Cost, µP Supervisory Circuits +12V +5V VCC 1M 1% TO µP RESET MAX70_ MAX70_ MR 130k 1% RESET PFI PFO GND R1 PARAMETER MIN TYP MAX UNIT +12V Reset 10.67 10.87 11.50 Threshold at +25°C Figure 5. RESET Valid to Ground Circuit V Figure 6. Monitoring Both +5V and +12V +5V BUFFERED RESET TO OTHER SYSTEM COMPONENTS VCC 100k MR R1 MAX70_ 100k 2N3904 PFO PFI VCC VCC MAX70_ R2 RESET TO µP GND V- µP 4.
PAGE 9
Low-Cost, µP Supervisory Circuits PART TEMP.
PAGE 10
MAX705–MAX708/MAX813L Low-Cost, µP Supervisory Circuits 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.) DIM C α A 0.101mm 0.004 in e B A1 L A A1 B C D E e H L α INCHES MAX MIN 0.044 0.036 0.008 0.004 0.014 0.010 0.007 0.005 0.120 0.116 0.120 0.116 0.0256 0.198 0.188 0.026 0.016 6° 0° MILLIMETERS MIN MAX 0.91 1.11 0.10 0.20 0.25 0.36 0.13 0.18 2.95 3.05 2.
PAGE 11
Maxim cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in a Maxim product. No circuit patent licenses are implied. Maxim reserves the right to change the circuitry and specifications without notice at any time. Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 408-737-7600 ____________________ 11 Printed USA is a registered trademark of Maxim Integrated Products, Inc. † †† 2.5 6 TBD TBD ✔ ✔ ✔ ✔ 6 10 TBD TBD TBD 1.