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General Description

The MAX690A/MAX692A/MAX802L/MAX802M/MAX805L

reduce the complexity and number of components

required for power-supply monitoring and battery-

control functions in microprocessor (μP) systems. They

significantly improve system reliability and accuracy

compared to separate ICs or discrete components.

These parts provide four functions:

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

brownout conditions.

2) Battery-backup switching for CMOS RAM, CMOS μP,

or other low-power logic.

3) A reset pulse if the optional watchdog timer has not

been toggled within 1.6s.

4) A 1.25V threshold detector for power-fail warning or

low-battery detection, or to monitor a power supply

other than +5V.

The parts differ in their reset-voltage threshold levels and

reset outputs. The MAX690A/MAX802L/MAX805L generate

a reset pulse when the supply voltage drops below 4.65V,

and the MAX692A/MAX802M generate a reset below 4.40V.

The MAX802L/MAX802M guarantee power-fail accuracies

to ±2%. The MAX805L is the same as the MAX690A except

that RESET is provided instead of RESET.

All parts are available in 8-pin DIP and SO packages.

The MAX690A/MAX802L are pin compatible with the

MAX690 and MAX694. The MAX692A/MAX802M are pin

compatible with the MAX692.

Applications

● Battery-Powered Computers and Controllers

● Intelligent Instruments

● Critical μP Power Monitoring

Features

● Precision Supply Voltage Monitor:

4.65V for MAX690A/MAX802L/MAX805L

4.40V for MAX692A/MAX802M

● Reset Time Delay: 200ms

● Watchdog Timer: 1.6s Timeout

● Battery-Backup Power Switching

● 200μA Quiescent Supply Current

● 50nA Quiescent Supply Current in Battery-

Backup Mode

● Voltage Monitor for Power-Fail or Low-Battery

Warning

● Power-Fail Accuracy Guaranteed to ±2%

(MAX802L/M)

● Guaranteed RESET Assertion to V

= 1V

● 8-Pin SO and DIP Packages

19-4333; Rev 5; 4/15

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 and SO packages are available in both

leaded and lead(Pb)-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.

PART TEMP RANGE PIN-PACKAGE

MAX690ACPA 0°C to +70°C 8 Plastic DIP

MAX690ACSA 0°C to +70°C 8 SO

MAX690AC/D 0°C to +70°C Dice*

MAX690AEPA -40°C to +85°C 8 Plastic DIP

MAX690AESA -40°C to +85°C 8 SO

MAX690AMJA -55°C to +125°C 8 CERDIP**

NMI

I/O LINE

GND

BUS

CMOS

RAM

UNREGULATED

REGULATED +5V

RESET

PFO

WDI

OUT

GND

BATT

PFI

0.1µF

3.6V

LITHIUM

BATTERY

MAX690A

MAX802L

µP

RESET

MAX690A/MAX692A/

MAX802L/MAX802M/

MAX805L

Microprocessor Supervisory Circuits

Typical Operating Circuit

Pin Congurations

Ordering Information

BATT

RESET (RESET)

WDI

PFO

PFI

GND

OUT

DIP/SO

TOP VIEW

MAX690A

MAX692A

MAX802L

MAX802M

MAX805L

( ) ARE FOR MAX805L ONLY.

Summary of content (13 pages)

PAGE 1
MAX690A/MAX692A/ MAX802L/MAX802M/ MAX805L Microprocessor Supervisory Circuits General Description The MAX690A/MAX692A/MAX802L/MAX802M/MAX805L reduce the complexity and number of components required for power-supply monitoring and batterycontrol functions in microprocessor (μP) systems. They significantly improve system reliability and accuracy compared to separate ICs or discrete components. These parts provide four functions: 1) A reset output during power-up, power-down, and brownout conditions.
PAGE 2
MAX690A/MAX692A/ MAX802L/MAX802M/ MAX805L Microprocessor Supervisory Circuits Absolute Maximum Ratings Terminal Voltage (with respect to GND) VCC. ..................................................................-0.3V to +6.0V VBATT................................................................-0.3V to +6.0V All Other Inputs (Note 1)........................... -0.3V to (VCC + 0.3V) Input Current VCC. ..............................................................................200mA VBATT...............
PAGE 3
MAX690A/MAX692A/ MAX802L/MAX802M/ MAX805L Microprocessor Supervisory Circuits Electrical Characteristics (continued) (VCC = 4.75V to 5.5V for MAX690A/MAX802L/MAX805L, VCC = 4.5V to 5.5V for MAX692A/MAX802M, VBATT = 2.8V, TA = TMIN to TMAX, unless otherwise noted.) PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS ISOURCE = 800μA RESET Output Voltage ISINK = 3.2mA 0.4 MAX69_AC, MAX802_C, VCC = 1.0V ISINK = 50μA 0.3 MAX69_AE/M, MAX802_E, VCC = 1.2V, ISINK = 100μA 0.
PAGE 4
MAX690A/MAX692A/ MAX802L/MAX802M/ MAX805L Microprocessor Supervisory Circuits Typical Operating Characteristics OUTPUT VOLTAGE vs. LOAD CURRENT 4.90 2.78 VOUT (V) 4.85 SLOPE = 80Ω RESET 0 10 20 40 30 50 2.70 0 0.4 0.2 0.6 0.8 +5V VCC +4V TA = +25°C PFO MAX690A-MAX805L toc06 +5V PFI 1V/div RESET GND +1.25V 10k +1.30V RESET 30pF PFO 1k 30pF +1.25V 1V/div +3V +1.
PAGE 5
MAX690A/MAX692A/ MAX802L/MAX802M/ MAX805L Microprocessor Supervisory Circuits Pin Description PIN MAX690A/MAX692A MAX802L/MAX802M MAX805L NAME FUNCTION 1 1 VOUT Supply Output for CMOS RAM. When VCC is above the reset threshold, VOUT connects to VCC through a P-channel MOSFET switch. When VCC is below the reset threshold, the higher of VCC or VBATT will be connected to VOUT. 2 2 VCC +5V Supply Input 3 3 GND Ground 4 4 PFI Power-Fail Comparator Input. When PFI is less than 1.
PAGE 6
MAX690A/MAX692A/ MAX802L/MAX802M/ MAX805L Microprocessor Supervisory Circuits BATTERY-SWITCHOVER CIRCUITRY VBATT VOUT +5V VCC VCC 0V RESET GENERATOR RESET (RESET) 1.25V VOUT 0V +5V 3.0V tRS RESET 3.5V 0V +5V (RESET) WATCHDOG TIMER WDI MAX690A MAX692A MAX802L MAX802M MAX805L 0.8V PFI 0V 3.0V +5V PFO PFO 0V 1.25V ( ) ARE FOR MAX805L ONLY. ( ) ARE FOR MAX805L ONLY. VBATT = PFI = 3.0V IOUT = 0mA GND Figure 1. Block Diagram Figure 2.
PAGE 7
MAX690A/MAX692A/ MAX802L/MAX802M/ MAX805L Microprocessor Supervisory Circuits VBATT VCC SW2 SW1 MAX690A MAX692A MAX802L MAX802M MAX805L D2 D3 0.1F + RESET (RESET) VBATT TO µP GND VOUT SW1/SW2 SW3/SW4 VCC > Reset Threshold Open Closed VCC < Reset Threshold and VCC > VBATT Open Closed VCC < Reset Threshold and VCC < VBATT Closed Open RESET THRESHOLD = 4.65V IN MAX690A/MAX802L/MAX805L. RESET THRESHOLD = 4.4V IN MAX692A/MAX802M Figure 3.
PAGE 8
MAX690A/MAX692A/ MAX802L/MAX802M/ MAX805L Microprocessor Supervisory Circuits +5V VIN +5V VCC R1 VOUT VCC TO STATIC RAM MAX692A MAX802M RESET VBATT 100kΩ 0.1F MAX690 MAX692A MAX802L MAX802M MAX805L PFI R3 C1* R2 PFO TO µP GND TO µP + GND *OPTIONAL +5V PFO 0V Figure 5. Using a SuperCap as a Backup Power Source with the MAX692A/MAX802M and a +5V ±10% Supply When VBATT connects to VOUT, backup mode is activated and the internal circuitry is powered from the battery (Table 1).
PAGE 9
MAX690A/MAX692A/ MAX802L/MAX802M/ MAX805L Microprocessor Supervisory Circuits Operation Without a Backup Power Source If a backup power source is not used, ground VBATT and connect VOUT to VCC. Since there is no need to switch over to any backup power source, VOUT does not need to be switched. A direct connection to VCC eliminates any voltage drops across the switch which may push VOUT below VCC.
PAGE 10
MAX690A/MAX692A/ MAX802L/MAX802M/ MAX805L Microprocessor Supervisory Circuits BUFFERED RESET TO OTHER SYSTEM COMPONENTS VCC MAX690A MAX692A MAX802L RESET MAX802M GND VCC 4.7kΩ RESET GND Figure 8. Interfacing to μPs with Bidirectional Reset I/O www.maximintegrated.
PAGE 11
MAX690A/MAX692A/ MAX802L/MAX802M/ MAX805L Microprocessor Supervisory Circuits μP Supervisory Circuits Part Number MAX690A/692A Nominal Reset Threshold (V) 4.65/4.40 Minimum Reset Pulse Width (ms) 140 Nominal Watchdog Timeout Period (s) 1.6 BackupBattery Switch ü CE Write Protect PowerFail Comparator ü MAX691A/693A 4.65/4.40 140/adj. 1.6/adj. ü ü/10ns MAX696 Adj. 35/adj. 1.6/adj. ü MAX697 Adj. 35/adj. 1.6/adj. MAX700 4.65/adj. 200 – MAX703/704 4.65/4.40 140 – MAX705/706 4.
PAGE 12
MAX690A/MAX692A/ MAX802L/MAX802M/ MAX805L Microprocessor Supervisory Circuits Ordering Information (continued) PART TEMP RANGE MAX692ACPA 0°C to +70°C 8 Plastic DIP MAX692ACSA 0°C to +70°C 8 SO MAX692AC/D 0°C to +70°C Dice* MAX692AEPA -40°C to +85°C 8 Plastic DIP MAX692AESA -40°C to +85°C 8 SO MAX692AMJA -55°C to +125°C 8 CERDIP** MAX802LCPA 0°C to +70°C 8 Plastic DIP MAX802LCSA 0°C to +70°C 8 SO MAX802LEPA -40°C to +85°C 8 Plastic DIP MAX802LESA -40°C to +85°C 8 SO MAX802M
PAGE 13
MAX690A/MAX692A/ MAX802L/MAX802M/ MAX805L Microprocessor Supervisory Circuits Revision History REVISION NUMBER REVISION DATE DESCRIPTION PAGES CHANGED 5 4/15 No /V OPNs in Ordering Information; deleted Automotive Systems in Applications Information section; added Package Information and Revision History tables 1, 12, 13 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.