MAX690AEPA+ - Maxim Integrated - Datasheet.Directory

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 VCC = 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 TA = +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**

VCC

NMI

I/O LINE GND

GND

BUS

CMOS

RAM

UNREGULATED

REGULATED +5V

RESET

PFO

WDI

VOUT

GND

VBATT

VCC

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

VBATT

RESET (RESET)

WDI

PFO

PFI

GND

VCC

VOUT

DIP/SO

TOP VIEW

MAX690A

MAX692A

MAX802L

MAX802M

MAX805L

( ) ARE FOR MAX805L ONLY.

Terminal Voltage (with respect to GND)

CC ...................................................................-0.3V to +6.0V

BATT ...............................................................-0.3V to +6.0V

All Other Inputs (Note 1) .......................... -0.3V to (VCC + 0.3V)

Input Current

CC ...............................................................................200mA

BATT .............................................................................50mA

GND ................................................................................20mA

Output Current

OUT .............................. Short-Circuit Protected for up to 10s

All Other Outputs ............................................................20mA

Rate of Rise, VCC, VBATT ..............................................100V/μs

Continuous Power Dissipation

Plastic DIP (derate 9.09mW/°C above +70°C) ............727mW

SO (derate 5.88mW/°C above +70°C) ....................... 471mW

CERDIP (derate 8.00mW/°C above +70°C) ................640mW

Operating Temperature Ranges:

MAX69_AC_ _, MAX80_ _ C_ _ ........................0°C to +70°C

MAX69_AE_ _, MAX80_ _ E_ _ ................... -40°C to +85°C

MAX69_AMJA, MAX805LMJA ..................... -55°C to +125°C

Storage Temperature Range ............................ -65°C to +160°C

Lead Temperature (soldering, 10s) ................................ +300°C

(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

Operating Voltage Range,

VCC, VBATT (Note 2)

MAX69_AC, MAX802_C 1.0 5.5

VMAX805LC 1.1 5.5

MAX69_AE/M, MAX80_ _E 1.2 5.5

Supply Current (Excluding IOUT)ISUPPLY

MAX69_AC, MAX802_C 200 350 µA

MAX69_AE/M, MAX802_E, MAX805LE/M 200 500

ISUPPLY in Battery-Backup

Mode (Excluding IOUT)

VCC = 0V,

VBATT = 2.8V

TA = +25°C 0.05 1.0 µA

TA = TMIN to TMAX 5.0

VBATT Standby Current

(Note 3)

5.5V > VCC >

VBATT +0.2V

TA = +25°C -0.1 0.02 µA

TA = TMIN to TMAX -1.0 0.02

VOUT Output

IOUT = 5mA VCC

- 0.05

VCC

- 0.025 V

IOUT = 50mA VCC

- 0. 5

VCC

- 0. 25

VOUT in Battery-Backup Mode IOUT = 250μA, VCC < VBATT - 0.2V VBATT

- 0.1

VBATT

- 0.02 V

Battery Switch Threshold, VCC

to VBATT VCC < VRT

Power-up 20 mV

Power-down -20

Battery Switchover Hysteresis 40 mV

Reset Threshold VRT

MAX690A, MAX802L, MAX805L 4.50 4.65 4.75

MAX692A, MAX802M 4.25 4.40 4.50

MAX802L, TA = +25°C, VCC falling 4.55 4.70

MAX802M, TA = +25°C, VCC falling 4.30 4.45

Reset Threshold Hysteresis 40 mV

Reset Pulse Width tRS 140 200 280 ms

MAX690A/MAX692A/

MAX802L/MAX802M/

MAX805L

Microprocessor Supervisory Circuits

www.maximintegrated.com Maxim Integrated

│

Absolute Maximum Ratings

Stresses beyond those listed under “Absolute Maximum Ratings” may cause permanent damage to the device. These are stress ratings only, and functional operation of the device at these

or any other conditions beyond those indicated in the operational sections of the specifications is not implied. Exposure to absolute maximum rating conditions for extended periods may affect

device reliability.

Electrical Characteristics

Note 1: The input voltage limits on PFI and WDI may be exceeded if the current into these pins is limited to less than 10mA.

(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.)

Note 2: Either VCC or VBATT can go to 0V, if the other is greater than 2.0V.

Note 3: “-” = battery-charging current, “+” = battery-discharging current.

Note 4: WDI is guaranteed to be in an intermediate, non-logic level state if WDI is floating and VCC is in the operating voltage

range. WDI is internally biased to 35% of VCC with an input impedance of 50kΩ.

PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS

RESET Output Voltage

ISOURCE = 800μA

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 0.3

RESET Output Voltage

MAX805LC, ISOURCE = 4μA, VCC = 1.1V 0.8

MAX805LE/M, ISOURCE = 4μA, VCC = 1.2V 0.9

MAX805L, ISOURCE = 800μA VCC - 1.5

MAX805L, ISINK = 3.2mA 0.4

Watchdog Timeout tWD 1.00 1.60 2.25 s

WDI Pulse Width tWP VIL = 0.4V, VIH = (0.8) (VCC)50 ns

WDI Input Threshold (Note 4) VCC = 5V Logic low 0.8 V

Logic high 3.5

WDI Input Current WDI = VCC 50 150 µA

WDI = 0V -150 -50

PFI Input Threshold MAX69_A, MAX805L, VCC = 5V 1.20 1.25 1.30 V

MAX802_C/E, VCC = 5V 1.225 1.250 1.275

PFI Input Current -25 0.01 25 nA

PFO Output Voltage ISOURCE = 800μA VCC - 1.5 V

ISINK = 3.2mA 0.4

MAX690A/MAX692A/

MAX802L/MAX802M/

MAX805L

Microprocessor Supervisory Circuits

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│

Electrical Characteristics (continued)

4.75

OUTPUT VOLTAGE

vs. LOAD CURRENT

4.80

5.00

IOUT (mA)

VOUT (V)

4.90

4.85

10 30 50

4.95

VCC = +5V

VBATT = +2.8V

TA = +25°C

SLOPE = 5Ω

MAX690A-MAX805L toc01

MAX690A

RESET RESPONSE TIME

2µs/div

VCC

+5V

RESET

+5V

+4V

1V/div

TA = +25°C

VCC VCC

GND

RESET

10k

RESET

30pF

MAX690A-MAX805L toc04

MAX805L RESET OUTPUT VOLTAGE

vs. SUPPLY VOLTAGE

500ms/div

VCC

+5V

1V/div

RESET

+5V

1V/div

10k

330

VCC

RESET

GND

VBATT

MAX690A-MAX805L toc07

MAX805L

RESET RESPONSE TIME

2µs/div

VCC +4V

+4V

+5V

GND

RESET

VCC

330pF 10k

MAX690A-MAX805L toc08

2.70

OUTPUT VOLTAGE

vs. LOAD CURRENT

2.72

2.80

IOUT (mA)

VOUT (V)

0.8

2.76

2.74

0.2 0.6 1.0

2.78

0.4

VCC = 0V

VBATT = +2.8V

TA = +25°C

SLOPE = 80Ω

MAX690A-MAX805L toc02

POWER-FAIL COMPARATOR

RESPONSE TIME

400ns/div

PFI

+1.30V

PFO

+5V

+0V

+1.2V

+5V

PFO

30pF

+1.25V

PFI

VCC = +5V

TA = +25°C

MAX690A-MAX805L toc05

MAX690A RESET OUTPUT VOLTAGE

vs. SUPPLY VOLTAGE

500ms/div

VCC

RESET

+5V

1V/div

+5V

1V/div

TA = +25°C

VBATT = OV

VCC VCC

GND

RESET

330pF

MAX690A-MAX805L toc03

POWER-FAIL COMPARATOR

RESPONSE TIME

400ns/div

PFI

+1.20V

PFO

+3V

+1.3V

VCC = +5V

TA = +25°C

+5V

PFO

30pF 1k

+1.25V

PFI

MAX690A-MAX805L toc06

MAX690A/MAX692A/

MAX802L/MAX802M/

MAX805L

Microprocessor Supervisory Circuits

Maxim Integrated

│

www.maximintegrated.com

Typical Operating Characteristics

NAME FUNCTION

MAX690A/MAX692A

MAX802L/MAX802M MAX805L

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.

5 5 PFO Power-Fail Output. When PFI is less than 1.25V, PFO goes low;

otherwise PFO stays high.

6 6 WDI

Watchdog Input. If WDI remains high or low for 1.6sec, the internal

watchdog timer runs out and reset is triggered. If WDI is left oating

or connected to a high-impedance three-state buffer, the watchdog

feature is disabled. The internal watchdog timer clears whenever reset is

asserted, WDI is three-stated, or WDI sees a rising or falling edge.

7 7 RESET

Reset Output. Whenever RESET is triggered, it pulses low for 200ms.

It stays low when VCC is below the reset threshold (4.65V in the

MAX690A/MAX802L and 4.4V in the MAX692A/MAX802M) and remains

low for 200ms after VCC rises above the reset threshold. A watchdog

timeout also triggers RESET.

— — RESET Active-High Reset Output is the inverse of RESET. When RESET is

asserted, the RESET output voltage = VCC or VBATT, whichever is

higher.

8 8 VBATT

Backup-Battery Input. When VCC falls below the reset threshold, VBATT

will be switched to VOUT if VBATT is 20mV greater than VCC. When VCC

rises to 20mV above VBATT, VOUT will be reconnected to VCC. The

40mV hysteresis prevents repeated switching if VCC falls slowly.

MAX690A/MAX692A/

MAX802L/MAX802M/

MAX805L

Microprocessor Supervisory Circuits

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│

Pin Description

Detailed Description

Reset Output

A microprocessor’s (μP’s) reset input starts the μP in

a known state. When the μP is in an unknown state,

it should be held in reset. The MAX690A/MAX692A/

MAX802L/MAX802M assert reset during power-up and

prevent code execution errors during power-down or

brownout conditions.

On power-up, once VCC reaches 1V, RESET is

guaranteed to be a logic low. As VCC rises, RESET

remains low. When VCC exceeds the reset threshold,

an internal timer keeps RESET low for a time equal to

the reset pulse width; after this interval, RESET goes

high (Figure 2). If a brownout condition occurs (if VCC

dips below the reset threshold), RESET is triggered.

Each time RESET is triggered, it stays low for the reset

pulse width interval. Any time VCC goes below the reset

threshold, the internal timer restarts the pulse. If a brownout

condition interrupts a previously initiated reset pulse,

the reset pulse continues for another 200ms. On power-

down, once VCC goes below the threshold, RESET is

guaranteed to be logic low until VCC droops below 1V.

RESET is also triggered by a watchdog timeout. If a high

or low is continuously applied to the WDI pin for 1.6sec,

RESET pulses low. As long as RESET is asserted, the

watchdog timer remains clear. When RESET comes

high, the watchdog resumes timing and must be serviced

within 1.6sec. If WDI is tied high or low, a RESET pulse is

triggered every 1.8s (tWD plus tRS).

The MAX805L active-high RESET output is the inverse

of the MAX690A/MAX692A/MAX802L/MAX802M RESET

output, and is guaranteed to be valid with VCC down to

1.1V. Some μPs, such as Intel’s 80C51, require an active-

high reset pulse.

Watchdog Input

The watchdog circuit monitors the μP’s activity. If the μP

does not toggle the watchdog input (WDI) within 1.6sec,

a reset pulse is triggered. The internal 1.6sec timer is

cleared by either a reset pulse or by open circuiting the

WDI input. As long as reset is asserted or the WDI input

is open circuited, the timer remains cleared and does not

count. As soon as reset is released or WDI is driven high

or low, the timer starts counting. It can detect pulses as

short as 50ns.

Power-Fail Comparator

The PFI input is compared to an internal 1.25V reference.

If PFI is less than 1.25V, PFO goes low. The power-

fail comparator is intended for use as an undervoltage

detector to signal a failing power supply; it need not be

Figure 1. Block Diagram Figure 2. Timing Diagram

0.8V

WATCHDOG

TIMER

PFO

RESET

(RESET)

VOUT

RESET

GENERATOR

BATTERY-SWITCHOVER

CIRCUITRY

1.25V

3.5V

VBATT

VCC

PFI

WDI

MAX690A

MAX692A

MAX802L

MAX802M

MAX805L

( ) ARE FOR MAX805L ONLY.

GND

1.25V

tRS

+5V

VCC

+5V

RESET

+5V

(RESET)

3.0V

VOUT

+5V

PFO

VBATT = PFI = 3.0V

IOUT = 0mA

( ) ARE FOR MAX805L ONLY.

MAX690A/MAX692A/

MAX802L/MAX802M/

MAX805L

Microprocessor Supervisory Circuits

www.maximintegrated.com Maxim Integrated

│

dedicated to this function though, as it is completely

separate from the rest of the circuitry. The external volt-

age divider drives PFI to sense the unregulated DC input

to the +5V regulator (see Typical Operating Circuit). The

voltage-divider ratio can be chosen such that the voltage

at PFI falls below 1.25V just before the +5V regulator

drops out. PFO then triggers an interrupt which signals

the μP to prepare for power-down.

To conserve backup-battery power, the power-fail

detector comparator is turned off and PFO is forced low

when VBATT connects to VOUT.

Backup-Battery Switchover

In the event of a brownout or power failure, it may be

necessary to preserve the contents of RAM. With a back-

up battery installed at VBATT, the devices automatically

switch RAM to backup power when VCC fails.

As long as VCC exceeds the reset threshold, VOUT

connects to VCC through a 5Ω PMOS power switch.

Once VCC falls below the reset threshold, VCC or VBATT

(whichever is higher) switches to VOUT. Unlike the

MAX690/MAX692, the MAX690A/MAX692A/MAX802L/

MAX802M/MAX805L don’t always connect VBATT to

VOUT when VBATT is greater than VCC. VBATT connects

to VOUT (through an 80Ω switch) only when VCC is below

the reset threshold and VBATT is greater than VCC.

When VCC exceeds the reset threshold, it is connected to

the MAX690A/MAX692A/MAX802L/MAX802M/MAX805L

substrate, regardless of the voltage applied to VBATT

(Figure 3). During this time, the diode (D1) between

VBATT and the substrate will conduct current from VBATT

to VCC if VBATT is 0.6V or greater than VCC.

Figure 3. Backup-Battery Switchover Block Diagram

Figure 4. Using a SuperCap as a Backup Power Source with a

MAX690A/MAX802L/MAX805L and a +5V ±5% Supply

Table 1. Wiper Position and Attenuation

SIGNAL STATUS

VCC Disconnected from VOUT

VOUT Connected to VBATT through an internal

80Ω PMOS switch

VBATT

Connected to VOUT. Current drawn from

the battery is less than 1μA, as long as

VCC < VBATT - 1V.

PFI Power-fail comparator is disabled.

PFO Logic low

RESET Logic low

RESET Logic high (MAX805L only)

WDI Watchdog timer is disabled

SW1/SW2 SW3/SW4CONDITION

VCC > Reset Threshold Open Closed

Closed

Open

Closed

VCC < Reset Threshold and

VCC > VBATT

VCC < Reset Threshold and

VCC < VBATT

RESET THRESHOLD = 4.65V IN MAX690A/MAX802L/MAX805L.

RESET THRESHOLD = 4.4V IN MAX692A/MAX802M

VOUT

SUBSTRATE

D1 D2

SW2

SW1 SW4

SW3

VBATT VCC

MAX690A

MAX692A

MAX802L

MAX802M

MAX805L VBATT

VCC VOUT

RESET

(RESET)

GND

TO STATIC RAM

TO µP

0.1F

MAX690A

MAX802L

MAX805L

+5V

( ) ARE FOR MAX805L ONLY.

MAX690A/MAX692A/

MAX802L/MAX802M/

MAX805L

Microprocessor Supervisory Circuits

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When VBATT connects to VOUT, backup mode is

activated and the internal circuitry is powered from

the battery (Table 1). When VCC is just below VBATT,

the current drawn from VBATT is typically 30μA. When

VCC drops to more than 1V below VBATT, the internal

switchover comparator shuts off and the supply current

falls to less than 1μA.

Applications Information

Using a SuperCap as a Backup Power Source

SuperCaps are capacitors with extremely high

capacitance values, on the order of 0.1F. Figure 4 shows

a SuperCap used as a backup power source. Do not allow

the SuperCap’s voltage to exceed the maximum reset

threshold by more than 0.6V. In Figure 4’s circuit, the

SuperCap rapidly charges to within a diode drop of VCC.

However, after a long time, the diode leakage current

will pull the SuperCap voltage up to VCC. When using a

SuperCap with the MAX690A/MAX802L/MAX805L, VCC

may not exceed 4.75V + 0.6V = 5.35V.

Use the SuperCap circuit of Figure 5 with a MAX692A

or MAX802M and a ±10% supply. This circuit ensures

that the SuperCap only charges to VCC - 0.5V. At the

maximum VCC of 5.5V, the SuperCap charges up to 5.0V,

only 0.5V above the maximum reset threshold—well

within the requisite 0.6V.

Allowable Backup Power-Source Batteries

Lithium batteries work very well as backup batteries

due to very low self-discharge rates and high energy

density. Single lithium batteries with open-circuit volt-

ages of 3.0V to 3.6V are ideal. Any battery with an open-

circuit voltage less than the minimum reset threshold

plus 0.3V can be connected directly to the VBATT input of

the MAX690A/MAX692A/MAX802L/MAX802M/MAX805L

with no additional circuitry (see the Typical Operating

Circuit). However, batteries with open-circuit voltages

that are greater cannot be used for backup, as current is

sourced into the substrate through the diode (D1 in Figure 3)

when VCC is close to the reset threshold.

Figure 5. Using a SuperCap as a Backup Power Source with

the MAX692A/MAX802M and a +5V ±10% Supply

Figure 6. Adding Hysteresis to the Power-Fail Comparator

Table 2. Allowable Backup-Battery

Voltages

(see Using a SuperCap as a Backup Power Source

section for use with a SuperCap)

PART NO. MAXIMUM BACKUP-BATTERY

VOLTAGE (V)

MAX690A/

MAX802L/MAX805L 4.80

MAX692A/

MAX802M 4.55

VBATT

VCC VOUT

RESET

GND

TO STATIC RAM

TO µP

0.1F

MAX692A

MAX802M

+5V

100kΩ

PFO

VCC

GND

TO µP

MAX690

MAX692A

MAX802L

MAX802M

MAX805L

+5V

PFI

*OPTIONAL

+5V

PFO

VLVH

VTRIP

VIN

C1*

VTRIP = 1.25/ R2

+ =

R2 + R2

(

VIH = 1.25/ R2 || R3

R1 + R2 || R3

(

VL - 1.25

5 - 1.25

1.25

MAX690A/MAX692A/

MAX802L/MAX802M/

MAX805L

Microprocessor Supervisory Circuits

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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.

Replacing the Backup Battery

The backup battery can be removed while VCC remains

valid, without danger of triggering RESET/RESET. As

long as VCC stays above the reset threshold, battery-

backup mode cannot be entered. In other switchover ICs

where battery-backup mode is entered whenever VBATT

gets close to VCC, an unconnected VBATT pin accumu-

lates leakage charge and triggers RESET/RESET in error.

Adding Hysteresis to the Power-Fail

Comparator

Hysteresis adds a noise margin to the power-fail

comparator and prevents repeated triggering of PFO

when VIN is close to its trip point. Figure 6 shows how to

add hysteresis to the power-fail comparator. Select the

ratio of R1 and R2 such that PFI sees 1.25V when VIN

falls to its trip point (VTRIP). R3 adds the hysteresis. It will

typically be an order of magnitude greater than R1 or R2

(about 10 times either R1 or R2). The current through R1

and R2 should be at least 1μA to ensure that the 25nA

(max) PFI input current does not shift the trip point. R3

should be larger than 10kΩ so it does not load down the

PFO pin. Capacitor C1 adds additional noise rejection.

Monitoring a Negative Voltage

The power-fail comparator can be used to monitor a

negative supply rail using the circuit of Figure 7. When

the negative rail is good (a negative voltage of large mag-

nitude), PFO is low. When the negative rail is degraded

(a negative voltage of lesser magnitude), PFO goes high.

This circuit’s accuracy is affected by the PFI threshold

tolerance, the VCC line, and the resistors.

Interfacing to μPs with Bidirectional

Reset Pins

μPs with bidirectional reset pins, such as the Motorola

68HC11 series, can contend with the MAX690A/MAX692A/

MAX802L/MAX802M RESET output. If, for example, the

RESET output is driven high and the μP wants to pull it

low, indeterminate logic levels may result. To correct this,

connect a 4.7kΩ resistor between the RESET output and

the μP reset I/O, as in Figure 8. Buffer the RESET output

to other system components.

Figure 7. Monitoring a Negative Voltage

PFO

VCC

GND

MAX690A

MAX692A

MAX802L

MAX802M

MAX805L

+5V

PFI

+5V

PFO

VTRIP

V- 0V

V-

NOTE: VTRIP IS NEGATIVE

VL - 1.25

1.25 - VTRIP

MAX690A/MAX692A/

MAX802L/MAX802M/

MAX805L

Microprocessor Supervisory Circuits

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Figure 8. Interfacing to μPs with Bidirectional Reset I/O

MAX690A

MAX692A

MAX802L

MAX802M

BUFFERED RESET TO OTHER SYSTEM COMPONENTS

4.7kΩ

VCC

GND

VCC

GND

RESET

MAX690A/MAX692A/

MAX802L/MAX802M/

MAX805L

Microprocessor Supervisory Circuits

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Part

Number

Nominal

Reset

Threshold

(V)

Minimum

Reset

Pulse

Width

(ms)

Nominal

Watchdog

Timeout

Period

(s)

Backup-

Battery

Switch

CE -

Write

Protect

Power-

Fail

Comparator

Manual-

Reset

Input

Watch-

dog

Output

Low-

Line

Output

Active-

High

Reset

Battery-

Output

MAX690A/692A 4.65/4.40 140 1.6 ü ü

MAX691A/693A 4.65/4.40 140/adj. 1.6/adj. ü ü/10ns ü ü ü ü ü

MAX696 Adj. 35/adj. 1.6/adj. ü ü ü ü ü ü

MAX697 Adj. 35/adj. 1.6/adj. ü ü ü ü ü

MAX700 4.65/adj. 200 – ü ü

MAX703/704 4.65/4.40 140 – ü ü ü

MAX705/706 4.65/4.40 140 1.6 ü ü ü

MAX706P 2.63 140 1.6 ü ü ü ü

MAX706R/S/T 2.63/2.93/

3.08 140 1.6 ü ü ü

MAX707/708 4.65/4.40 140 – ü ü ü

MAX708R/S/T 2.63/2.93/

3.08 140 – ü ü ü

MAX709L/M/

R/S/T 4.65/4.40/

2.63/2.93/3.08 140 –

MAX791 4.65 140 1 ü ü/10ns ü ü ü ü ü ü

MAX792L/M/

R/S/T 4.65/4.40/

2.63/2.93/3.08 140 1 ü/10ns ü ü ü ü ü

MAX800L/M 4.60/4.40 140 1.6/adj. ü ü/10ns ü/±2% ü ü ü ü

MAX802L/M 4.60/4.40 140 1.6 ü ü/±2%

MAX805L 4.65 140 1.6 ü ü ü

MAX813L 4.65 140 1.6 ü ü ü ü

MAX820L/M/

R/S/T 4.65/4.40/

2.63/2.93/3.08 140 1 ü/10ns ü/±2% ü ü ü ü

MAX1232 4.37/4.62 250 0.15/0.60/1.2 ü ü

MAX1259 – – – ü ü

MAX690A/MAX692A/

MAX802L/MAX802M/

MAX805L

Microprocessor Supervisory Circuits

www.maximintegrated.com Maxim Integrated

│

μP Supervisory Circuits

*Dice are specified at TA = +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

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

MAX802MCPA 0°C to +70°C 8 Plastic DIP

MAX802MCSA 0°C to +70°C 8 SO

MAX802MEPA -40°C to +85°C 8 Plastic DIP

MAX802MESA -40°C to +85°C 8 SO

MAX805LCPA 0°C to +70°C 8 Plastic DIP

MAX805LCSA 0°C to +70°C 8 SO

MAX805LC/D 0°C to +70°C Dice*

MAX805LEPA -40°C to +85°C 8 Plastic DIP

MAX805LESA -40°C to +85°C 8 SO

MAX805LMJA -55°C to +125°C 8 CERDIP**

RESET (RESET)

GND

VBATT

PFI

0.061"

(1.55mm)

0.078"

(1.98mm)

( ) ARE FOR MAX805L ONLY.

TRANSISTOR COUNT: 573;

SUBSTRATE MUST BE LEFT UNCONNECTED.

WDI

PFO

VCC VOUT

MAX690A/MAX692A/

MAX802L/MAX802M/

MAX805L

Microprocessor Supervisory Circuits

www.maximintegrated.com Maxim Integrated

│

Ordering Information (continued)

For the latest package outline information and land patterns, go

to www.maximintegrated.com/packages. Note that a “+”, “#”,

or “-” in the package code indicates RoHS status only. Package

drawings may show a different suffix character, but the drawing

pertains to the package regardless of RoHS status.

Package Information

PACKAGE

TYPE

PACKAGE e

CODE

OUTLINE

NO.

LAND

PATTERN NO.

8 PDIP P8+1 21-0043 —

8 CDIP J8+2 21-0045 —

8 SOIC S8+2 21-0041 90-0096

Chip Topography

Maxim Integrated cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in a Maxim Integrated product. No circuit patent licenses

are implied. Maxim Integrated reserves the right to change the circuitry and specications without notice at any time. The parametric values (min and max limits)

shown in the Electrical Characteristics table are guaranteed. Other parametric values quoted in this data sheet are provided for guidance.

Maxim Integrated and the Maxim Integrated logo are trademarks of Maxim Integrated Products, Inc.

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.

Mouser Electronics

Authorized Distributor

Click to View Pricing, Inventory, Delivery & Lifecycle Information:

Maxim Integrated:

MAX690ACPA+ MAX690ACSA+ MAX690AESA+ MAX692ACPA+ MAX692ACSA+ MAX692AESA+

MAX802LCPA+ MAX802LCSA+ MAX802LCSA+T MAX802MCPA+ MAX802MCSA+ MAX802MCSA+T

MAX805LCPA+ MAX805LCSA+ MAX805LCSA+T MAX6315US29D1+T MAX690ACSA+T MAX690AEPA+

MAX690AESA+T MAX692ACSA+T MAX692AEPA+ MAX692AESA+T MAX690AMJA MAX692AMJA MAX690AESA