MAX803/9/10

General Description

The MAX803/MAX809/MAX810 are microprocessor (µP)

supervisory circuits used to monitor the power supplies

in µP and digital systems. They provide excellent circuit

reliability and low cost by eliminating external compo-

nents and adjustments when used with +5V, +3.3V,

+3.0V, or +2.5V-powered circuits.

These circuits perform a single function: they assert a

reset signal whenever the V

supply voltage declines

below a preset threshold, keeping it asserted for at

least 140ms after V

has risen above the reset thresh-

old. Reset thresholds suitable for operation with a vari-

ety of supply voltages are available.

The MAX803 has an open-drain output stage, while the

MAX809/MAX810 have push-pull outputs. The

MAX803’s open-drain RESET output requires a pull-up

resistor that can be connected to a voltage higher than

. The MAX803/MAX809 have an active-low RESET

output, while the MAX810 has an active-high RESET

output. The reset comparator is designed to ignore fast

transients on V

, and the outputs are guaranteed to

be in the correct logic state for V

down to 1V.

Low supply current makes the MAX803/MAX809/

MAX810 ideal for use in portable equipment. The

MAX803 is available in a 3-pin SC70 package, and the

MAX809/MAX810 are available in 3-pin SC70 or SOT23

packages.

Applications

Computers

Controllers

Intelligent Instruments

Critical µP and µC Power Monitoring

Portable/Battery-Powered Equipment

Automotive

____________________________Features

o Precision Monitoring of +2.5V, +3V, +3.3V, and

+5V Power-Supply Voltages

o Fully Specified Over Temperature

o Available in Three Output Configurations

Open-Drain RESET Output (MAX803)

Push-Pull RESET Output (MAX809)

Push-Pull RESET Output (MAX810)

o 140ms min Power-On Reset Pulse Width

o 12µA Supply Current

o Guaranteed Reset Valid to V

= +1V

o Power Supply Transient Immunity

o No External Components

o 3-Pin SC70 and SOT23 Packages

MAX803L/M/R/S/T/Z, MAX809J/L/M/R/S/T/Z, MAX810L/M/R/S/T/Z

3-Pin Microprocessor Reset Circuits

________________________________________________________________ Maxim Integrated Products

TOP VIEW

RESET (RESET)

GND

MAX803

MAX809

MAX810

SC70-3/SOT23-3

( ) ARE FOR MAX810.

MAX803 AVAILABLE IN SC70-3 ONLY.

MAX803

MAX809

PULL-UP

RESET

INPUT

GND

*MAX803 ONLY

µP

Pin Configuration

Typical Operating Circuit

19-0344; Rev 4; 12/99

Note: These parts are offered in 2.5k or 10k reels, and must be

ordered in 2.5k or 10k increments. Order MAX803_EXR-T for

2.5k reels and MAX803_EXR-T10 for 10k reels. Insert the

desired suffix letter from the Selector Guide into the blank to

complete the part number. All versions of these products may

not be available at the time of announcement. Contact factory for

availability.

For free samples & the latest literature: http://www.maxim-ic.com, or phone 1-800-998-8800.

For small orders, phone 1-800-835-8769.

3 SC70-3

-40°C to +105°C

MAX803_EXR-T10

3 SC70-3

PIN-PACKAGE

TEMP. RANGE

-40°C to +105°C

MAX803_EXR-T

PART

3 SC70-3

-40°C to +105°C

MAX809_EXR-T10

3 SC70-3

-40°C to +105°C

MAX809_EXR-T

3 SOT23-3

-40°C to +105°C

MAX809_EUR-T10

3 SOT23-3

-40°C to +105°C

MAX809_EUR-T

3 SC70-3

-40°C to +105°C

MAX810_EXR-T10

3 SC70-3

-40°C to +105°C

MAX810_EXR-T

3 SOT23-3

-40°C to +105°C

MAX810_EUR-T10

3 SOT23-3

-40°C to +105°C

MAX810_EUR-T

Ordering Information

MAX803L/M/R/S/T/Z, MAX809J/L/M/R/S/T/Z, MAX810L/M/R/S/T/Z

3-Pin Microprocessor Reset Circuits

_______________________________________________________________________________________

ABSOLUTE MAXIMUM RATINGS

ELECTRICAL CHARACTERISTICS

= full range, T

= -40°C to +105°C, unless otherwise noted. Typical values are at T

= +25°C, V

= 5V for L/M/J versions, V

= 3.3V for T/S versions, V

= 3V for R version, and V

= 2.5V for Z version.) (Note 1)

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.

Terminal Voltage (with respect to GND)

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

RESET, RESET (push-pull) .....................-0.3V to (V

+ 0.3V)

RESET (open drain)...........................................-0.3V to +6.0V

Input Current, V

..............................................................20mA

Output Current, RESET, RESET ..........................................20mA

Rate of Rise, V

............................................................100V/µs

Continuous Power Dissipation (T

= +70°C)

3-Pin SC70 (derate 2.17mW/°C above +70°C) ............174mW

3-Pin SOT23 (derate 4mW/°C above +70°C)...............320mW

Operating Temperature Range .........................-40°C to +105°C

Storage Temperature Range .............................-65°C to +150°C

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

= -40°C to

+85°C

= -40°C to +105°C

= 0°C to +70°C

= +85°C to

+105°C

MAX8_ _Z

(SC70 only)

= -40°C to

+85°C

< 3.6V, MAX8_ _R/S/T

= +85°C to

+105°C

MAX8_ _L

CONDITIONS

2.21

2.45

2.25

2.38

2.28

2.32

2.35

2.50

2.76

4.50

4.75

4.56

4.63

4.70

Reset Threshold

Supply Current (SOT23)

1.2

5.5

1.0

5.5

Range

µA

Supply Current (SC70)

< 5.5V, MAX8_ _L/M

< 3.6V, MAX8_ _R/S/T

< 5.5V, MAX8_ _L/M

< 3.6V, MAX8_ _R/S/T/Z

100

UNITS

MIN

TYP

MAX

SYMBOL

PARAMETER

< 5.5V, MAX8_ _J/L/M

< 5.5V, MAX8_ _L/M

MAX8_ _S

2.89

2.93

2.96

= +25°C

< 3.6V, MAX8_ _R/S/T/Z

= +25°C

= -40°C to +85°C

MAX8_ _M

4.25

4.50

2.85

3.00

= -40°C to +85°C

MAX8_ _R

2.55

2.70

2.59

2.63

2.66

2.78

3.08

= +85°C to +105°C

= +25°C

= -40°C to +85°C

4.31

4.38

4.45

4.40

4.86

= +85°C to +105°C

= +25°C

= -40°C to +85°C

MAX809J

(SOT only)

3.93

4.00

4.06

4.16

4.56

= +85°C to +105°C

= +25°C

3.89

4.10

= -40°C to +85°C

3.80

4.20

= +85°C to +105°C

MAX8_ _T

2.92

3.23

3.00

3.15

3.04 3.08

3.11

= +25°C

= -40°C to +85°C

= +85°C to +105°C

= +25°C

= -40°C to +85°C

= +85°C to +105°C

MAX803L/M/R/S/T/Z, MAX809J/L/M/R/S/T/Z, MAX810L/M/R/S/T/Z

3-Pin Microprocessor Reset Circuits

_______________________________________________________________________________________

Note 1: Production testing done at T

= +25°C; limits over temperature guaranteed by design only.

Note 2: RESET output for MAX803/MAX809; RESET output for MAX810.

= -40°C to +85°C

= +85°C to +105°C

= -40°C to +85°C

= V

to (V

- 100mV)

CONDITIONS

140

240

460

Reset Active Timeout Period

(SC70)

100

840

140

240

560

Reset Active Timeout Period

(SOT23)

µs

to Reset Delay (Note 2)

ppm/°C

Reset Threshold Tempco

UNITS

MIN

TYP

MAX

SYMBOL

PARAMETER

= +85°C to +105°C

= V

max, I

SINK

= 3.2mA,

MAX810L/M

= V

max, I

SINK

= 1.2mA,

MAX810R/S/T/Z

> V

max, I

SOURCE

= 800µA,

MAX809J/L/M

> V

max, I

SOURCE

= 500µA,

MAX809R/S/T/Z

= V

min, I

SINK

= 1.2mA,

MAX803R/S/T/Z, MAX809R/S/T/Z

= V

min, I

SINK

= 3.2mA,

MAX803L/M, MAX809J/L/M

> V

, RESET deasserted

> 1.0V, I

SINK

= 50µA

1.8V < V

< V

min, I

SOURCE

= 150µA

µA

RESET Open-Drain Output

Leakage Current (MAX803)

0.8V

RESET Output Voltage High

(push-pull active high, MAX810)

100

840

0.4

0.3

RESET Output Voltage Low

(push-pull active high, MAX810)

- 1.5

0.8V

RESET Output Voltage High

(push-pull active low, MAX809)

0.3

RESET Output Voltage Low

(push-pull active low and open-

drain active-low, MAX803 and

MAX809)

0.4

0.3

POWER-DOWN RESET DELAY vs.

TEMPERATURE (MAX8_ _R/S/T/Z)

100

MAX803-TOC3

TEMPERATURE (°C)

POWER-DOWN RESET DELAY (

-40

-20

= V

- V

= 20mV

= 10mV

= 200mV

= 100mV

Typical Operating Characteristics

= full range, T

= -40°C to +105°C, unless otherwise noted. Typical values are at T

= +25°C, V

= +5V for L/M/J versions,

= +3.3V for T/S versions, V

= +3V for R version, and V

= +2.5V for Z version.)

ELECTRICAL CHARACTERISTICS (continued)

= full range, T

= -40°C to +105°C, unless otherwise noted. Typical values are at T

= +25°C, V

= 5V for L/M/J versions, V

= 3.3V for T/S versions, V

= 3V for R version, and V

= 2.5V for Z version.) (Note 1)

-40

-20

SUPPLY CURRENT vs. TEMPERATURE

(SC70 PACKAGE, NO LOAD)

MAX803 toc01

TEMPERATURE (°C)

SUPPLY CURRENT (

MAX8_ _R/S/T, V

= 3.3V

MAX8_ _L/M/R/S/T/Z, V

= 1V

MAX8_ _Z, V

= 2.5V

MAX8_ _L/M, V

= 5V

MAX803L/M/R/S/T/Z, MAX809J/L/M/R/S/T/Z, MAX810L/M/R/S/T/Z

3-Pin Microprocessor Reset Circuits

_______________________________________________________________________________________

Typical Operating Characteristics (continued)

= full range, T

= -40°C to +105°C, unless otherwise noted. Typical values are at T

= +25°C, V

= +5V for L/M/J versions,

= +3.3V for T/S versions, V

= +3V for R version, and V

= +2.5V for Z version.)

225

POWER-UP RESET TIMEOUT

vs. TEMPERATURE

245

250

MAX803-TOC5

TEMPERATURE (°C)

POWER-UP RESET TIMEOUT (ms)

235

230

240

-40

-20

MAX8_ _R/S/T/Z

MAX8_ _J/L/M

0.997

NORMALIZED RESET THRESHOLD

vs. TEMPERATURE

1.001

1.002

1.003

MAX803-TOC6

TEMPERATURE (°C)

NORMALIZED THRESHOLD

0.999

0.998

1.000

-40

-20

3.08

MAX803T

4.38

4.63

MAX803L

MAX803M

2.93

MAX809S

3.08

MAX809T

4.00

MAX809J

Open-Drain RESET

4.38

MAX809M

Open-Drain RESET

Push-Pull RESET

2.93

MAX803S

Push-Pull RESET

2.63

MAX803R

Push-Pull RESET

Open-Drain RESET

2.32

MAX803Z

Open-Drain RESET

4.63

MAX809L

Push-Pull RESET

OUTPUT TYPE

RESET THRESHOLD (V)

PART/SUFFIX

—

ADAA

ACAA

CWAA

ABAA

—

AAAA

TOP MARK

ABB

ABA

AAZ

AAQ

AAP

—

AAO

ABC

ABD

ABE

AAN

AHAA

AGAA

—

AFAA

AAU

AAT

AAS

AAR

4.38

MAX810M

4.63

MAX810L

2.32

MAX809Z

2.63

MAX809R

Push-Pull RESET

AKAA

AJAA

AAX

AAV

2.93

MAX810S

3.08

MAX810T

Push-Pull RESET

MAX810R

2.63

Push-Pull RESET

ALAA

AAW

MAX810Z

2.32

Push-Pull RESET

—

AAY

SOT

SC70

Selector Guide

POWER-DOWN RESET DELAY vs.

TEMPERATURE (MAX8_ _J/L/M)

100

120

140

MAX803-TOC4

TEMPERATURE (°C)

POWER-DOWN RESET DELAY (

-40

-20

= V

- V

= 10mV

= 100mV

= 200mV

= 20mV

MAX803L/M/R/S/T/Z, MAX809J/L/M/R/S/T/Z, MAX810L/M/R/S/T/Z

_______________________________________________________________________________________

Detailed Description

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

known state. The MAX803/MAX809/MAX810 assert

reset to prevent code-execution errors during power-

up, power-down, or brownout conditions. They assert a

reset signal whenever the V

supply voltage declines

below a preset threshold, keeping it asserted for at

least 140ms after V

has risen above the reset thresh-

old. The MAX803 uses an open-drain output, and the

MAX809/MAX810 have a push-pull output stage.

Connect a pull-up resistor on the MAX803’s RESET out-

put to any supply between 0 and 6V.

Applications Information

Negative-Going V

Transients

In addition to issuing a reset to the µP during power-up,

power-down, and brownout conditions, the MAX803/

MAX809/MAX810 are relatively immune to short-duration

negative-going V

transients (glitches).

Figure 1 shows typical transient duration vs. reset com-

parator overdrive, for which the MAX803/MAX809/

MAX810 do not generate a reset pulse. The graph was

generated using a negative-going pulse applied to V

starting 0.5V above the actual reset threshold and end-

ing below it by the magnitude indicated (reset compara-

tor overdrive). The graph indicates the maximum pulse

width a negative-going V

transient can have without

causing a reset pulse. As the magnitude of the transient

increases (goes farther below the reset threshold), the

maximum allowable pulse width decreases. Typically, for

the MAX8__L and MAX8__M, a V

transient that goes

100mV below the reset threshold and lasts 20µs or less

will not cause a reset pulse. A 0.1µF bypass capacitor

mounted as close as possible to the V

pin provides

additional transient immunity.

Ensuring a Valid Reset Output

Down to V

= 0

When V

falls below 1V, the MAX809 RESET output

no longer sinks current—it becomes an open circuit.

Therefore, high-impedance CMOS logic inputs con-

nected to RESET can drift to undetermined voltages.

This presents no problem in most applications since

most µP and other circuitry is inoperative with V

below 1V. However, in applications where RESET must

be valid down to 0V, adding a pull-down resistor to

RESET causes any stray leakage currents to flow to

3-Pin Microprocessor Reset Circuits

100k

GND

MAX809

RESET

Figure 2. RESET Valid to V

= Ground Circuit

RESET

(MAX803/

MAX809)

RESET Output remains low while V

is below the reset threshold, and for at

least 140ms after V

rises above the

reset threshold.

GND

Ground

PIN

NAME

FUNCTION

RESET

(MAX810)

RESET Output remains high while V

is below the reset threshold, and for at

least 140ms after V

rises above the

reset threshold.

_____________________Pin Description

400

320

100

1000

160

240

RESET COMPARATOR OVERDRIVE, V

- V

(mV)

MAXIMUM TRANSIENT DURATION (

= +25°C

MAX8_ _J/L/M

MAX8_ _R/S/T/Z

Figure 1. Maximum Transient Duration Without Causing a

Reset Pulse vs. Reset Comparator Overdrive

Supply Voltage (+5V, +3.3V, +3.0V, or

+2.5V)

MAX803L/M/R/S/T/Z, MAX809J/L/M/R/S/T/Z, MAX810L/M/R/S/T/Z

ground, holding RESET low (Figure 2). R1’s value is not

critical; 100k

Ω is large enough not to load RESET and

small enough to pull RESET to ground.

A 100k

Ω pull-up resistor to V

is also recommended

for the MAX810 if RESET is required to remain valid for

< 1V.

Interfacing to µPs with

Bidirectional Reset Pins

Since the RESET output on the MAX803 is open drain,

this device interfaces easily with µPs that have bidirec-

tional reset pins, such as the Motorola 68HC11.

Connecting the µP supervisor’s RESET output directly

to the microcontroller’s (µC’s) RESET pin with a single

pull-up resistor allows either device to assert reset

(Figure 3).

MAX803 Open-Drain RESET Output

Allows Use with Multiple Supplies

Generally, the pull-up connected to the MAX803 will

connect to the supply voltage that is being monitored at

the IC’s V

pin. However, some systems may use the

open-drain output to level-shift from the monitored sup-

ply to reset circuitry powered by some other supply

(Figure 4). Note that as the MAX803’s V

decreases

below 1V, so does the IC’s ability to sink current at

RESET. Also, with any pull-up, RESET will be pulled

high as V

decays toward 0. The voltage where this

occurs depends on the pull-up resistor value and the

voltage to which it is connected.

Benefits of Highly Accurate

Reset Threshold

Most µP supervisor ICs have reset threshold voltages

between 5% and 10% below the value of nominal sup-

ply voltages. This ensures a reset will not occur within

5% of the nominal supply, but will occur when the sup-

ply is 10% below nominal.

When using ICs rated at only the nominal supply ±5%,

this leaves a zone of uncertainty where the supply is

between 5% and 10% low, and where the reset may or

may not be asserted.

The MAX8_ _L/T/Z use highly accurate circuitry to

ensure that reset is asserted close to the 5% limit, and

long before the supply has declined to 10% below

nominal.

3-Pin Microprocessor Reset Circuits

_______________________________________________________________________________________

RESET

GND

RESET

INPUT

PULLUP

MAX803

5V SYSTEM

GND

+3.3V

+5.0V

Figure 4. MAX803 Open-Drain RESET Output Allows Use with

Multiple Supplies

RESET

GND

RESET

INPUT

MAX803

MOTOROLA

68HCXX

µP

GND

Figure 3. Interfacing to µPs with Bidirectional Reset I/O

TRANSISTOR COUNT: 275 (SOT23)

380 (SC70)

___________________Chip Information