MAX811REUS+T - Hytronics - Datasheet.Cloud

________________General Description

The MAX811/MAX812 are low-power microprocessor

(µP) supervisory circuits used to monitor power sup-

plies in µP and digital systems. They provide excellent

circuit reliability and low cost by eliminating external

components and adjustments when used with 5V-

powered or 3V-powered circuits. The MAX811/MAX812

also provide a debounced manual reset input.

These devices perform a single function: They assert a

reset signal whenever the VCC supply voltage falls

below a preset threshold, keeping it asserted for at

least 140ms after VCC has risen above the reset thresh-

old. The only difference between the two devices is that

the MAX811 has an active-low RESET output (which is

guaranteed to be in the correct state for VCC down to

1V), while the MAX812 has an active-high RESET out-

put. The reset comparator is designed to ignore fast

transients on VCC. Reset thresholds are available for

operation with a variety of supply voltages.

Low supply current makes the MAX811/MAX812 ideal

for use in portable equipment. The devices come in a

4-pin SOT143 package.

________________________Applications

Computers

Controllers

Intelligent Instruments

Critical µP and µC Power Monitoring

Portable/Battery-Powered Equipment

____________________________Features

♦♦Precision Monitoring of 3V, 3.3V, and 5V

Power-Supply Voltages

♦♦6µA Supply Current

♦♦140ms Min Power-On Reset Pulse Width;

RREESSEETTOutput (MAX811), RESET Output (MAX812)

♦♦Guaranteed Over Temperature

♦♦Guaranteed RREESSEETTValid to VCC = 1V (MAX811)

♦♦Power-Supply Transient Immunity

♦♦No External Components

♦♦4-Pin SOT143 Package

MAX811/MAX812

4-Pin µP Voltage Monitors

with Manual Reset Input

________________________________________________________________

Maxim Integrated Products

VCC

MR(RESET) RESET

GND

MAX811

MAX812

SOT143

TOP VIEW

( ) ARE FOR MAX812

NOTE: SEE LAST PAGE FOR MARKING INFORMATION.

___________________Pin Configuration

MAX811

MAX812

VCC

RESET

(RESET)

RESET

INPUT

GND

VCC

GND

μP

( ) ARE FOR MAX812

PUSHBUTTON

SWITCH

___________Typical Operating Circuit

19-0411; Rev 4; 12/05

PART*

MAX811_EUS-T

MAX812_EUS-T -40°C to +85°C

-40°C to +85°C

TEMP RANGE PIN-PACKAGE

4 SOT143

_______________Ordering Information

This part offers a choice of five different reset threshold volt-

ages. Select the letter corresponding to the desired nominal

reset threshold voltage, and insert it into the blank to complete

the part number.

Devices are available in both leaded and lead-free packaging.

Specify lead-free by replacing “-T” with “+T” when ordering.

RESET THRESHOLD

SUFFIX VOLTAGE (V)

L4.63

M4.38

T3.08

S2.93

R2.63

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.

MAX811/MAX812

4-Pin µP Voltage Monitors

with Manual Reset Input

2 _______________________________________________________________________________________

ABSOLUTE MAXIMUM RATINGS

ELECTRICAL CHARACTERISTICS

(VCC = 5V for L/M versions, VCC = 3.3V for T/S versions, VCC = 3V for R version, TA= -40°C to +85°C, unless otherwise noted.

Typical values are at TA= +25°C.) (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)

VCC ......................................................................-0.3V to 6.0V

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

Input Current, VCC, MR .......................................................20mA

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

Continuous Power Dissipation (TA= +70°C)

SOT143 (derate 4mW/°C above +70°C) .......................320mW

Operating Temperature Range ...........................-40°C to +85°C

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

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

ISOURCE = 150µA, 1.8V < VCC < VTH(MIN)

MAX81_R/S/T, VCC = 3.6V, IOUT = 0

MAX81_L/M, VCC = 5.5V, IOUT = 0

TA= -40°C to +85°C

VOD = 125mV, MAX81_R/S/T

VOD = 125mV, MAX81_L/M

MAX81_S

MAX81_L

MAX81_M

VCC = VTH(MAX)

CONDITIONS

0.8 x VCC

2.3VIH

µs0.5tMD

MR to Reset Propagation Delay

(Note 2)

ns100

MR Glitch Immunity (Note 3)

µs10tMR

MR Minimum Pulse Width

ms140 560tRP

Reset Active Timeout Period

µA

2.7 10

ICC

Supply Current 615

1.2

VCC

Operating Voltage Range

µs

VCC to Reset Delay (Note 2) 40

2.88 2.93 2.98

3.03 3.08 3.14

Reset Threshold

4.54 4.63 4.72

4.50 4.75

4.30 4.38 4.46

4.25 4.50

UNITSMIN TYP MAXSYMBOLPARAMETER

MAX812L/M only, ISINK = 3.2mA,

VCC = VTH(MAX)

MAX812R/S/T only, ISINK = 1.2mA,

VCC = VTH(MAX) V

0.4

VOL

RESET Output Voltage

(MAX812)

0.3

VOH

VCC > VTH(MAX), MAX81_L/M 0.8VIL

VCC > VTH(MAX), MAX81_R/S/T

0.25 x VCC

VIL

MR Input Threshold 0.7 x VCC

VIH

kΩ10 20 30

MR Pull-Up Resistance

TA= 0°C to +70°C 1.0 5.5

3.00 3.15

2.85 3.00

ppm/°C30Reset Threshold Tempco

MAX81_R 2.58 2.63 2.68

2.55 2.70

TA = +25°C

TA = -40°C to +85°C

TA = +25°C

TA = -40°C to +85°C

MAX81_T TA = +25°C

TA = -40°C to +85°C

TA = +25°C

TA = -40°C to +85°C

TA = +25°C

TA = -40°C to +85°C

VTH V

MAX811/MAX812

4-Pin µP Voltage Monitors

with Manual Reset Input

_______________________________________________________________________________________ 3

ELECTRICAL CHARACTERISTICS (continued)

(VCC = 5V for L/M versions, VCC = 3.3V for T/S versions, VCC = 3V for R version, TA= -40°C to +85°C, unless otherwise noted.

Typical values are at TA= +25°C.) (Note 1)

Note 1: Production testing done at TA= +25°C, over temperature limits guaranteed by design using six sigma design limits.

Note 2: RESET output for MAX811, RESET output for MAX812.

Note 3: “Glitches” of 100ns or less typically will not generate a reset pulse.

MAX811R/S/T only, ISINK = 1.2mA,

VCC = VTH(MIN)

MAX811L/M only, ISOURCE = 800µA,

VCC > VTH(MAX)

MAX811L/M only, ISINK = 3.2mA,

VCC = VTH(MIN)

ISINK = 50µA, VCC > 1.0V

MAX811R/S/T only, ISOURCE = 500µA,

VCC > VTH(MAX)

CONDITIONS

0.3

VCC - 1.5

VOH

RESET Output Voltage

(MAX811)

0.4

0.3

VOL

0.8 x VCC

UNITSMIN TYP MAXSYMBOLPARAMETER

MAX811/MAX812

4-Pin µP Voltage Monitors

with Manual Reset Input

4 _______________________________________________________________________________________

190

POWER-UP RESET TIMEOUT

vs. TEMPERATURE

230

MAX811/12-TOC5

TEMPERATURE (°C)

POWER-UP RESET TIMEOUT (ms)

210

200

220

-40 85

35-15 10 60

MAX81_R/S/T

MAX81_L/M

RESET THRESHOLD DEVIATION

vs. TEMPERATURE

0.9995

1.0000

1.0005

MAX811/12-TOC6

TEMPERATURE (°C)

NORMALIZED THRESHOLD (V)

0.9985

0.9980

0.9990

-40 8535-15 10 60

POWER-DOWN RESET DELAY vs. TEMPERATURE

(MAX81_L/M)

200

MAX811/12-TOC4

TEMPERATURE (°C)

POWER-DOWN RESET DELAY (μs)

100

150

-40 8510-15 6035

VOD = VTH - VCC

VOD = 125mV

VOD = 200mV

VOD = 20mV

__________________________________________Typical Operating Characteristics

(TA = +25°C, unless otherwise noted.)

-40 85

SUPPLY CURRENT vs. TEMPERATURE

(MAX81_R/S/T)

2.0

2.5

3.0

MAX811/12-TOC1

TEMPERATURE (°C)

SUPPLY CURRENT (μA)

1.0

0.5

-15 60

1.5

VCC = 3.6V

VCC = 3.3V

VCC = 1V

SUPPLY CURRENT vs. TEMPERATURE

(MAX81_L/M)

MAX811/12-TOC2

TEMPERATURE (°C)

SUPPLY CURRENT (μA)

-40 85

10-15 6035

VCC = 5.5V

VCC = 3V

VCC = 1V

POWER-DOWN RESET DELAY vs. TEMPERATURE

(MAX81_R/S/T)

100

MAX811/12-TOC3

TEMPERATURE (°C)

POWER-DOWN RESET DELAY (μs)

-40 85

10-15 6035

VOD = VTH - VCC

VOD = 20mV

VOD = 200mV

VOD = 125mV

MAX811/MAX812

4-Pin µP Voltage Monitors

with Manual Reset Input

_______________________________________________________________________________________ 5

______________________________________________________________ Pin Description

_______________ Detailed Description

Reset Output

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

known state. These µP supervisory circuits assert reset

to prevent code execution errors during power-up,

power-down, or brownout conditions.

RESET is guaranteed to be a logic low for VCC > 1V.

Once VCC exceeds the reset threshold, an internal

timer keeps RESET low for the reset timeout period;

after this interval, RESET goes high.

If a brownout condition occurs (VCC dips below the

reset threshold), RESET goes low. Any time VCC goes

below the reset threshold, the internal timer resets to

zero, and RESET goes low. The internal timer starts

after VCC returns above the reset threshold, and RESET

remains low for the reset timeout period.

The manual reset input (MR) can also initiate a reset.

See the

Manual Reset Input

section.

The MAX812 has an active-high RESET output that is

the inverse of the MAX811’s RESET output.

Manual Reset Input

Many µP-based products require manual reset capabil-

ity, allowing the operator, a test technician, or external

logic circuitry to initiate a reset. A logic low on MR

asserts reset. Reset remains asserted while MR is low,

and for the Reset Active Timeout Period (tRP) after MR

returns high. This input has an internal 20kΩpull-up

resistor, so it can be left open if it is not used. MR can

be driven with TTL or CMOS-logic levels, or with open-

drain/collector outputs. Connect a normally open

momentary switch from MR to GND to create a manual-

reset function; external debounce circuitry is not

required. If MR is driven from long cables or if the

device is used in a noisy environment, connecting a

0.1µF capacitor from MR to ground provides additional

noise immunity.

Reset Threshold Accuracy

The MAX811/MAX812 are ideal for systems using a 5V

±5% or 3V ±5% power supply with ICs specified for 5V

±10% or 3V ±10%, respectively. They are designed to

meet worst-case specifications over temperature. The

reset is guaranteed to assert after the power supply

falls out of regulation, but before power drops below

the minimum specified operating voltage range for the

system ICs. The thresholds are pre-trimmed and exhibit

tight distribution, reducing the range over which an

undesirable reset may occur.

Manual Reset Input. A logic low on MR asserts reset. Reset remains asserted as long as MR is

low and for 180ms after MR returns high. This active-low input has an internal 20kΩpull-up

resistor. It can be driven from a TTL or CMOS-logic line, or shorted to ground with a switch.

Leave open if unused.

+5V, +3.3V, or +3V Supply Voltage44

Active-High Reset Output. RESET remains high while VCC is below the reset threshold or while

MR is held low. RESET remains high for Reset Active Timeout Period (tRP) after the reset condi-

tions are terminated.

2—

Active-Low Reset Output. RESET remains low while VCC is below the reset threshold or while

MR is held low. RESET remains low for the Reset Active Timeout Period (tRP) after the reset

conditions are terminated.

—2

Ground

FUNCTION

VCC

RESET

GND

NAME

MAX811 MAX812

MAX811/MAX812

__________ Applications Information

Negative-Going VCC Transients

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

power-down, and brownout conditions, the MAX811/

MAX812 are relatively immune to short duration nega-

tive-going VCC transients (glitches).

Figure 1 shows typical transient durations vs. reset

comparator overdrive, for which the MAX811/MAX812

do not generate a reset pulse. This graph was generat-

ed using a negative-going pulse applied to VCC, start-

ing above the actual reset threshold and ending below

it by the magnitude indicated (reset comparator over-

drive). The graph indicates the typical maximum pulse

width a negative-going VCC transient may have without

causing a reset pulse to be issued. As the magnitude

of the transient increases (goes farther below the reset

threshold), the maximum allowable pulse width

decreases. Typically, a VCC transient that goes 125mV

below the reset threshold and lasts 40µs or less

(MAX81_L/M) or 20µs or less (MAX81_T/S/R) will not

cause a reset pulse to be issued. A 0.1µF capacitor

mounted as close as possible to VCC provides addi-

tional transient immunity.

Ensuring a Valid

RESET

Output

Down to VCC = 0V

When VCC falls below 1V, the MAX811 RESET output

no longer sinks current—it becomes an open circuit.

Therefore, high-impedance CMOS-logic inputs con-

nected to the RESET output can drift to undetermined

voltages. This presents no problem in most applica-

tions, since most µP and other circuitry is inoperative

with VCC below 1V. However, in applications where the

RESET output must be valid down to 0V, adding a pull-

down resistor to the RESET pin will cause any stray

leakage currents to flow to ground, holding RESET low

(Figure 2). R1’s value is not critical; 100kΩis large

enough not to load RESET and small enough to pull

RESET to ground.

A 100kΩpull-up resistor to VCC is also recommended

for the MAX812 if RESET is required to remain valid for

VCC < 1V.

4-Pin µP Voltage Monitors

with Manual Reset Input

6 _______________________________________________________________________________________

1 100 1000

RESET COMPARATOR OVERDRIVE , VTH - VCC (mV)

MAXIMUM TRANSIENT DURATION (ms)

TA = +25°C

MAX81 _L/M

MAX81 _R/S/T

VCC

GND

MAX811

RESET

Figure 1. Maximum Transient Duration without Causing a

Reset Pulse vs. Comparator Overdrive

Figure 2. RESET Valid to VCC = Ground Circuit

Interfacing to µPs with

Bidirectional Reset Pins

µPs with bidirectional reset pins (such as the Motorola

68HC11 series) can contend with the MAX811/MAX812

reset outputs. If, for example, the MAX811 RESET out-

put is asserted high and the µP wants to pull it low,

indeterminate logic levels may result. To correct such

cases, connect a 4.7kΩresistor between the MAX811

RESET (or MAX812 RESET) output and the µP reset I/O

(Figure 3). Buffer the reset output to other system com-

ponents.

MAX811/MAX812

4-Pin µP Voltage Monitors

with Manual Reset Input

_______________________________________________________________________________________ 7

4.7k

VCC

GND

RESET

MAX811

RESET

VCC

GND

μP

BUFFER

BUFFERED RESET

TO OTHER SYSTEM

COMPONENTS

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

TRANSISTOR COUNT: 341

___________________Chip Information

MAX811/MAX812

4-Pin µP Voltage Monitors

with Manual Reset Input

4.0 ±0.1

2.0 ±0.05 1.75 ±0.1

ø1.5 ±0.1

ø1.1 ±0.1

8.0 ±0.2

3.5 ±0.05

X X X X

LOT SPECIFIC

CODE

MARKING

INFORMATION

NOTE: DIMENSIONS ARE IN MM.

AND FOLLOW EIA481-1 STANDARD.

ICs MAY ALSO BE MARKED WITH FULL PART NAME: 811L, 811M_…

†

AMAA or KABB = MAX811L

ANAA or KABC = MAX811M

APAA or KABD = MAX811T

AQAA or KABE = MAX811S

ARAA or KABF = MAX811R

ASAA or KABG = MAX812L

ATAA or KABH = MAX812M

AVAA or KABI = MAX812T

AWAA or KABJ = MAX812S

AXAA or KABK = MAX812R

SOT-23 5L .EPS

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

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.)