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MAX690A/MAX692A/MAX802L/MAX802M/MAX805L

Microprocessor Supervisory Circuits

________________________________________________________________ Maxim Integrated Products 1

BATT

RESET (RESET)

WDI

PFO

PFI

GND

OUT

DIP/SO

TOP VIEW

MAX690A

MAX692A

MAX802L

MAX802M

MAX805L

( ) ARE FOR MAX805L ONLY.

_________________Pin Configurations

NMI

I/O LINE

GND

BUS

CMOS

RAM

GND

UNREGULATED DC REGULATED +5V

RESET

PFO

WDI

OUT

GND

BATT

PFI

O.1µF

3.6V

LITHIUM

BATTERY

MAX690A

MAX802L

µP

RESET

__________Typical Operating Circuit

19-4333; Rev 4; 12/05

__________________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 signifi-

cantly 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 1.6sec.

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 guaran-

tee 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

Automotive Systems

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 – 1.6sec 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

RREESSEETT

Assertion to V

= 1V

♦ 8-Pin SO and DIP Packages

______________Ordering Information

PART TEMP. RANGE PIN-PACKAGE

MAX690ACPA

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**

Ordering Information continued on last page.

* 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-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

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 (12 pages)

PAGE 1
9-4333; Rev 4; 12/05 Microprocessor Supervisory Circuits 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.
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 . . . . . . . . . . . . . . . . . . . . . . . . .
PAGE 3
Microprocessor Supervisory Circuits (V CC = 4.75V to 5.5V for MAX690A/MAX802L/MAX805L, V CC = 4.5V to 5.5V for MAX692A/MAX802M, V BATT = 2.8V, TA = TMIN to TMAX, unless otherwise noted.) PARAMETER SYMBOL CONDITIONS MAX805LC, ISOURCE = 4µA, VCC = 1.1V MAX805LE/M, ISOURCE = 4µA, VCC = 1.2V RESET Output Voltage MAX805L, ISOURCE = 800µA MIN TYP tWD WDI Pulse Width tWP 0.9 VCC - 1.5 V WDI Input Threshold (Note 4) 0.4 1.00 VIL = 0.4V, VIH = (0.8) (VCC) VCC = 5V PFI Input Threshold 3.
PAGE 4
__________________________________________Typical Operating Characteristics OUTPUT VOLTAGE vs. LOAD CURRENT 5.00 2.78 VOUT (V) 4.90 4.85 VBATT = OV TA = +25°C VCC = 0V VBATT = +2.8V TA = +25°C VCC 2.76 +5V 0V VCC VCC 2.74 SLOPE = 80Ω GND 0V 2.70 0 10 30 20 0 50 40 0.2 0.6 0.4 IOUT (mA) 0.8 1.
PAGE 5
Microprocessor Supervisory Circuits 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 1.25V, PFO goes low. Connect PFI to GND or VCC when not used.
PAGE 6
MAX690A/MAX692A/MAX802L/MAX802M/MAX805L Microprocessor Supervisory Circuits VBATT +5V BATTERY-SWITCHOVER CIRCUITRY VOUT VCC 0V VCC RESET GENERATOR 3.5V RESET (RESET) 1.25V 0V +5V tRS 3.0V RESET 0V +5V (RESET) WATCHDOG TIMER WDI VOUT 3.0V 0V MAX690A MAX692A MAX802L MAX802M MAX805L 0.8V PFI +5V PFO PFO 0V 1.25V ( ) ARE FOR MAX805L ONLY. GND ( ) ARE FOR MAX805L ONLY. VBATT = PFI = 3.0V IOUT = 0mA Figure 1. Block Diagram Figure 2.
PAGE 7
Microprocessor Supervisory Circuits VCC +5V SW1 SW2 SW4 SW3 D1 VOUT VCC TO STATIC RAM D2 MAX690A MAX802L VBATT MAX805L RESET (RESET) SUBSTRATE MAX690A MAX802L MAX805L MAX692A MAX802M D3 TO µP + 0.1F VOUT GND CONDITION 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 ( ) ARE FOR MAX805L ONLY. RESET THRESHOLD = 4.65V IN MAX690A/MAX802L/MAX805L. RESET THRESHOLD = 4.
PAGE 8
MAX690A/MAX692A/MAX802L/MAX802M/MAX805L Microprocessor Supervisory Circuits VIN +5V +5V R1 VOUT VCC VCC TO STATIC RAM MAX692A MAX802M PFI RESET VBATT TO µP R3 R2 C1* + 100k 0.1F MAX690 MAX692A MAX802L MAX802M MAX805L PFO GND GND TO µP *OPTIONAL +5V Figure 5. Using a SuperCap™ as a Backup Power Source with the MAX692A/MAX802M and a +5V ±10% Supply PFO 0V When VBATT connects to VOUT, backup mode is activated and the internal circuitry is powered from the battery (Table 1).
PAGE 9
Microprocessor Supervisory Circuits Operation Without a Backup Power Source If a backup power source is not used, ground V BATT 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. Replacing the Backup Battery The backup battery can be removed while VCC remains valid, without danger of triggering RESET/RESET.
PAGE 10
MAX690A/MAX692A/MAX802L/MAX802M/MAX805L Microprocessor Supervisory Circuits BUFFERED RESET TO OTHER SYSTEM COMPONENTS VCC MAX690A MAX692A MAX802L RESET MAX802M GND VCC 4.7k RESET GND Figure 8.
PAGE 11
Microprocessor Supervisory Circuits Part Number Minimum Nominal Reset Reset Pulse Threshold Width (V) (ms) Nominal Watchdog Timeout Backup- CE Period Battery Write (sec) Switch Protect MAX690A/692A 4.65/4.40 140 1.6 ✔ MAX691A/693A 4.65/4.40 140/adj. 1.6/adj. ✔ MAX696 Adj. 35/adj. 1.6/adj. ✔ MAX697 Adj. 35/adj. 1.6/adj. MAX700 4.65/adj. 200 - MAX703/704 4.65/4.40 140 - MAX705/706 4.65/4.40 140 MAX706P 2.63 MAX706R/S/T 2.63/2.93/ 3.
PAGE 12
MAX690A/MAX692A/MAX802L/MAX802M/MAX805L Microprocessor Supervisory Circuits __Ordering Information (continued) PART MAX692ACPA TEMP.