Datasheet

ManualsBrandsMAXIM INTEGRATED ManualsPMICsPMIC - system monitor Reset/power-on reset SOIC 8

_______________General Description

In applications with microprocessors (µPs) that have a

RESET input, the MAX7705 is functionally and socket

compatible with the TL7705, but requires no external

components. It provides power-supply glitch immunity

and a guaranteed power-up reset delay, while typically

consuming 1/27

the power from a +5V supply.

The MAX7705 monitors the power supply in µP and digital

systems. The RESET output is valid for V

down to 1V.

The device offers excellent circuit reliability and low cost

by eliminating external components and adjustments.

A system reset is provided during power-up, power-

down, and brownout conditions. When V

is below the

reset threshold, RESET is low and holds the µP in reset.

RESET will go high 280ms after V

rises above the

reset threshold. The MAX7705 is available in 8-pin DIP

and SO packages.

________________________Applications

Minimum Component Count, Low-Cost

Processor Systems

____________________________Features

♦ No External Components

♦ Low Cost

♦ Precise Reset Threshold

♦ 280ms Power-On Reset Delay

♦ 8-Pin DIP and SO Packages

______________Ordering Information

* Contact factory for dice specifications.

MAX7705

µP Power-Supply Monitor

with Reset

________________________________________________________________

Maxim Integrated Products

N.C.

RESET

GND

N.C.

MAX7705

RESET

GND

µP

* THE MAX7705 ELIMINATES THREE EXTERNAL 

COMPONENTS REQUIRED BY THE TL7705.

__________________Pin Configuration

N.C.

RESET

GND

N.C.

MAX7705

DIP/SO

TOP VIEW



__________Typical Operating Circuit

Call toll free 1-800-998-8800 for free samples or literature.

19-0151; Rev 0; 6/93

PART TEMP. RANGE PIN-PACKAGE

MAX7705CPA 0°C to +70°C 8 Plastic DIP

MAX7705CSA 0°C to +70°C 8 SO

MAX7705C/D 0°C to +70°C Dice*

FEATURE MAX7705 TL7705

No. of External

Components Required

Operating Supply

Current

65µA

1.8mA

Power-Supply Glitch

Immunity

Yes

Guaranteed Minimum

Reset Delay

Yes

+5V

+3V

35µA

1.8mA

MAX7705EPA -40°C to +85°C 8 Plastic DIP

MAX7705ESA -40°C to +85°C 8 SO

Summary of content (8 pages)

PAGE 1
9-0151; Rev 0; 6/93 µP Power-Supply Monitor with Reset FEATURE ♦ No External Components ♦ Low Cost ♦ Precise Reset Threshold ♦ 280ms Power-On Reset Delay ♦ 8-Pin DIP and SO Packages ______________Ordering Information PART TEMP. RANGE PIN-PACKAGE MAX7705 TL7705 MAX7705CPA 0°C to +70°C 8 Plastic DIP 0 3 MAX7705CSA 0°C to +70°C 8 SO MAX7705C/D 0°C to +70°C MAX7705EPA -40°C to +85°C 8 Plastic DIP MAX7705ESA -40°C to +85°C 8 SO No.
PAGE 2
MAX7705 µP Power-Supply Monitor with Reset ABSOLUTE MAXIMUM RATINGS Terminal Voltage (with respect to GND) VCC ......................................................................-0.3V to 6.0V RESET....................................................-0.3V to (VCC + 0.3V) Input Current, VCC ..............................................................20mA Output Current, RESET ......................................................20mA Rate-of-Rise, VCC ....................................................
PAGE 3
µP Power-Supply Monitor with Reset POWER-UP RESET DELAY vs. TEMPERATURE SUPPLY CURRENT vs. TEMPERATURE 100 250 200 150 100 80 60 -60 -20 20 60 VCC = +5V VCC = +4V 40 VCC = +3V 0 0 4.660 NO LOAD 20 50 4.665 NOTE: STEADY-STATE SUPPLY CURRENT IS INDEPENDENT OF RESET OUTPUT STATUS 100 VCC = +2V 4.650 4.645 4.640 4.630 -20 20 60 100 TEMPERATURE (°C) TEMPERATURE (°C) 4.655 4.
PAGE 4
MAXIMUM TRANSIENT DURATION (µs) MAX7705 µP Power-Supply Monitor with Reset 150 TA = +25°C 100 50 10ns 0 10 100 1k 10k RESET COMPARATOR OVERDRIVE, VTH - VCC (mV) Figure 1. Maximum Transient Duration without Causing a Reset Pulse vs. Reset Comparator Overdrive __________Applications Information Replacing the TL7705 with a MAX7705 in an Existing Design The MAX7705 has only three active pins: VCC, GND, and RESET.
PAGE 5
µP Power-Supply Monitor with Reset µPs with bidirectional reset pins, such as Motorola’s 68HC11 series, can contend with the MAX7705 reset output. If, for example, the MAX7705 RESET output is asserted high and the µP wants to pull it low, an indeterminate logic level may result. To correct this, connect a 4.7kΩ resistor between the MAX7705 RESET output and the µP reset I/O, as in Figure 3. Buffer the RESET signal to other system components.
PAGE 6
MAX7705 µP Power-Supply Monitor with Reset _______________________________________________________Package Information DIM D1 A A1 A2 A3 B B1 C D D1 E E1 e eA eB L α E E1 D A3 A A2 L A1 MILLIMETERS MIN MAX – 5.08 0.38 – 3.18 4.45 1.40 2.03 0.41 0.56 1.27 1.65 0.20 0.30 8.84 9.91 0.13 0.89 7.62 8.26 6.10 7.11 2.54 BSC 7.62 BSC – 10.16 2.92 3.81 0˚ 15˚ 21-324A α C e B1 B 6 INCHES MAX MIN 0.200 – – 0.015 0.175 0.125 0.080 0.055 0.022 0.016 0.065 0.050 0.012 0.008 0.390 0.348 0.035 0.005 0.325 0.
PAGE 7
µP Power-Supply Monitor with Reset DIM E A A1 B C D E e H h L α H INCHES MAX MIN 0.069 0.053 0.010 0.004 0.019 0.014 0.010 0.007 0.197 0.189 0.157 0.150 0.050 BSC 0.244 0.228 0.020 0.010 0.050 0.016 8˚ 0˚ MILLIMETERS MIN MAX 1.35 1.75 0.10 0.25 0.35 0.49 0.19 0.25 4.80 5.00 3.80 4.00 1.27 BSC 5.80 6.20 0.25 0.50 0.40 1.27 0˚ 8˚ 21-325A h x 45˚ D α A 0.127mm 0.004in.
PAGE 8
MAX7705 µP Power-Supply Monitor with Reset µ P 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 2.63 140 MAX706R/S/T 2.63/2.93/ 3.