Document
19-0151; Rev 0; 6/93
µP Power-Supply Monitor with Reset
_______________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 1/27th the power from a +5V supply. The MAX7705 monitors the power supply in µP and digital systems. The RESET output is valid for VCC 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, powerdown, and brownout conditions. When VCC is below the reset threshold, RESET is low and holds the µP in reset. RESET will go high 280ms after VCC rises above the reset threshold. The MAX7705 is available in 8-pin DIP and SO packages.
FEATURE MAX7705 0 65µA 35µA Yes Yes TL7705 3 1.8mA 1.8mA No No
____________________________Features
o No External Components o Low Cost o Precise Reset Threshold o 280ms Power-On Reset Delay o 8-Pin DIP and SO Packages
MAX7705
______________Ordering Information
PART MAX7705CPA MAX7705CSA MAX7705C/D MAX7705EPA MAX7705ESA TEMP. RANGE 0°C to +70°C 0°C to +70°C 0°C to +70°C -40°C to +85°C -40°C to +85°C PIN-PACKAGE 8 Plastic DIP 8 SO Dice* 8 Plastic DIP 8 SO
No. of External Components Required Operating Supply Current Power-Supply Glitch Immunity Guaranteed Minimum Reset Delay
+5V +3V
* Contact factory for dice specifications.
________________________Applications
Minimum Component Count, Low-Cost Processor Systems
__________Typical Operating Circuit
__________________Pin Configuration
VCC
TOP VIEW *
1 2 3 N.C. 1 N.C. 2 N.C. 3 GND 4 8 7 VCC N.C. N.C. RESET
MAX7705
N.C. N.C. N.C. GND VCC 8 N.C. 7 N.C. 6 RESET 5 RESET GND
µP
*
*
4
MAX7705
6 5
DIP/SO
* THE MAX7705 ELIMINATES THREE EXTERNAL COMPONENTS REQUIRED BY THE TL7705.
________________________________________________________________ Maxim Integrated Products
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Call toll free 1-800-998-8800 for free samples or literature.
µP Power-Supply Monitor with Reset MAX7705
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 ............................................................100V/µs Continuous Power Disipation (TA = +70°C) Plastic DIP (derate 9.09mW/°C above +70°C) ............727mW SO (derate 5.88mW/°C above +70°C) .........................471mW Operating Temperature Ranges: MAX7705C_ _ .....................................................0°C to +70°C MAX7705E_ _ ..................................................-40°C to +85°C Storage Temperature Range .............................-65°C to +160°C Lead Temperature (soldering, 10sec) .............................+300°C
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
(VCC = full range, TA = TMIN to TMAX, unless otherwise noted.) PARAMETER MAX7705C VCC Range MAX7705E MAX7705C, VCC < 5.5V Supply Current MAX7705E, VCC < 5.5V RESET Threshold VCC to RESET Delay Reset Active Timeout Period VCC = reset threshold max to reset threshold min VCC = reset threshold max, VCC rising ISINK = 3.2mA, VCC = reset threshold min RESET Output Voltage ISINK = 50µA, VCC ≥ 1.0V, MAX7705C ISINK = 100µA, VCC ≥ 1.2V, MAX7705E ISOURCE = 800µA, VCC ≥ reset threshold max VCC - 1.5 140 4.50 65 4.65 20 280 560 0.4 0.3 V 0.4 200 4.75 V µs ms 1.2 65 5.5 150 µA CONDITIONS MIN 1.0 TYP MAX 5.5 V UNITS
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µP Power-Supply Monitor with Reset
__________________________________________Typical Operating Characteristics
(TA = +25°C, unless otherwise noted.)
MAX7705
POWER-UP RESET DELAY vs. TEMPERATURE
300 POWER-UP RESET DELAY (ms) 250 200 150 100 50 0 -60 -20 20 60 100 TEMPERATURE (°C) VCC = RESET THRESHOLD MAX VCC RISING SUPPLY CURRENT (µA) 100
SUPPLY CURRENT vs. TEMPERATURE
NOTE: STEADY-STATE SUPPLY CURRENT IS INDEPENDENT OF RESET OUTPUT STATUS NO LOAD 60 VCC = +5V VCC = +4V 40 VCC = +3V 20 0 VCC = +2V VCC = +1V -60 -20 20 60 100 TEMPERATURE (°C) RESET THRESHOLD (V) 4.665 4.660 4.655 4.650 4.645 4.640 4.635 4.630 -60
RESET THRESHOLD vs. TEMPERATURE
80
-20
20
60
100
TEMPERATURE (°C)
POWER-DOWN RESET DELAY vs. TEMPERA.