Datasheet

ManualsBrandsMAXIM INTEGRATED ManualsPMICsPMIC - system monitor Reset/power-on reset SOT 143 4

________________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 V

supply voltage falls

below a preset threshold, keeping it asserted for at

least 140ms after V

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 V

down to

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

put. The reset comparator is designed to ignore fast

transients on V

. 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;

RREESSEETT

Output (MAX811), RESET Output (MAX812)

♦ Guaranteed Over Temperature

♦ Guaranteed

RREESSEETT

Valid to V

= 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 1

MR(RESET) RESET

GND

MAX811

MAX812

SOT143

TOP VIEW

( ) ARE FOR MAX812

NOTE: SEE LAST PAGE FOR MARKING INFORMATION.

___________________Pin Configuration

MAX811

MAX812

RESET

(RESET)

RESET

INPUT

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)

L 4.63

M 4.38

T 3.08

S 2.93

R 2.63

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.

Summary of content (8 pages)

PAGE 1
9-0411; Rev 4; 12/05 4-Pin µP Voltage Monitors with Manual Reset Input ____________________________Features The MAX811/MAX812 are low-power microprocessor (µP) supervisory circuits used to monitor power supplies in µP and digital systems. They provide excellent circuit reliability and low cost by eliminating external components and adjustments when used with 5Vpowered or 3V-powered circuits. The MAX811/MAX812 also provide a debounced manual reset input. ♦ Precision Monitoring of 3V, 3.
PAGE 2
MAX811/MAX812 4-Pin µP Voltage Monitors with Manual Reset Input ABSOLUTE MAXIMUM RATINGS 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 .......................................
PAGE 3
4-Pin µP Voltage Monitors with Manual Reset Input (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) PARAMETER SYMBOL VOL RESET Output Voltage (MAX811) VOH CONDITIONS MIN TYP MAX MAX811R/S/T only, ISINK = 1.2mA, VCC = VTH(MIN) 0.3 MAX811L/M only, ISINK = 3.2mA, VCC = VTH(MIN) 0.4 ISINK = 50µA, VCC > 1.0V 0.3 MAX811R/S/T only, ISOURCE = 500µA, VCC > VTH(MAX) 0.
PAGE 4
__________________________________________Typical Operating Characteristics (TA = +25°C, unless otherwise noted.) SUPPLY CURRENT vs. TEMPERATURE (MAX81_L/M) VCC = 3.3V 1.5 1.0 0.5 VCC = 3V 2 -40 POWER-DOWN RESET DELAY vs. TEMPERATURE (MAX81_L/M) POWER-UP RESET TIMEOUT vs. TEMPERATURE VOD = 20mV 150 100 50 VOD = 125mV VOD = 200mV 0 -40 -15 10 35 TEMPERATURE (°C) 60 -15 60 85 -40 230 MAX81_R/S/T 210 MAX81_L/M 35 60 85 1.0005 1.0000 0.9995 0.9990 0.9985 0.
PAGE 5
4-Pin µP Voltage Monitors with Manual Reset Input PIN NAME FUNCTION MAX811 MAX812 1 1 GND 2 — RESET 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 RESET Active-High Reset Output. RESET remains high while VCC is below the reset threshold or while MR is held low.
PAGE 6
MAX811/MAX812 4-Pin µP Voltage Monitors with Manual Reset Input MAXIMUM TRANSIENT DURATION (ms) 8 TA = +25°C 7 6 VCC MAX81 _L/M 5 4 MAX811 MAX81 _R/S/T 3 RESET 2 R1 1 GND 0 1 10 100 1000 RESET COMPARATOR OVERDRIVE , VTH - VCC (mV) Figure 1. Maximum Transient Duration without Causing a Reset Pulse vs.
PAGE 7
4-Pin µP Voltage Monitors with Manual Reset Input 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 output is asserted high and the µP wants to pull it low, indeterminate logic levels may result. To correct such cases, connect a 4.7kΩ resistor between the MAX811 RESET (or MAX812 RESET) output and the µP reset I/O (Figure 3). Buffer the reset output to other system components.
PAGE 8
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.) 4.0 ±0.1 ø1.5 ±0.1 1.75 ±0.1 2.0 ±0.05 8.0 ±0.2 3.5 ±0.05 4.0 ±0.1 ø1.1 ±0.1 NOTE: DIMENSIONS ARE IN MM. AND FOLLOW EIA481-1 STANDARD.