MAX802MEPA ,Microprocessor Supervisory CircuitsMAX690A/MAX692A/MAX802L/MAX802M/MAX805LBUS 19-4333; Rev 3; 9/93Microprocessor Supervisory Circuits_ ..
MAX802MESA ,Microprocessor Supervisory CircuitsGeneral Description _______
MAX802REPA ,3.0V or 3.3V microprocessor supervisory circuit. Reset threshold 2.625V. Active-low reset. Watchdog input. Backup-battery switch. Power-fail threshold accuracy +-2%. Power-fail comparator. Reset window +-2%Applicationsvoltage (T = 3.075V, S = 2.925V, R = 2.625V) and insert it intoBattery-Powered Computer ..
MAX802RESA ,3.0V or 3.3V microprocessor supervisory circuit. Reset threshold 2.625V. Active-low reset. Watchdog input. Backup-battery switch. Power-fail threshold accuracy +-2%. Power-fail comparator. Reset window +-2%General Description ________
MAX802SCPA ,3.0V or 3.3V microprocessor supervisory circuit. Reset threshold 2.925V. Active-low reset. Watchdog input. Backup-battery switch. Power-fail threshold accuracy +-2%. Power-fail comparator. Reset window +-2%Applicationsvoltage (T = 3.075V, S = 2.925V, R = 2.625V) and insert it intoBattery-Powered Computer ..
MAX802SCSA ,3.0V or 3.3V microprocessor supervisory circuit. Reset threshold 2.925V. Active-low reset. Watchdog input. Backup-battery switch. Power-fail threshold accuracy +-2%. Power-fail comparator. Reset window +-2%ELECTRICAL CHARACTERISTICS(V = 3.17V to 5.5V for the MAX690T/MAX704T/MAX80_T, V = 3.02V to 5.5V for ..
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MB8117800A-60 ,2 M X 8 BIT FAST PAGE MODE DYNAMIC RAMapplications where very low power dissipation and high bandwidth are basic requirements of the desi ..
MB81464- ,MOS 262144 Bit DRAMfeatures page mode which allows high speed
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MAX690ACPA-MAX690ACSA-MAX690AEPA-MAX690AESA-MAX690AMJA-MAX692ACPA-MAX692ACSA-MAX692AEPA-MAX692AESA-MAX692AMJA-MAX802LCPA-MAX802LCSA-MAX802LESA-MAX802MCPA-MAX802MCSA-MAX802MEPA-MAX802MESA-MAX805LCPA-MAX805LCSA-MAX805LESA
Microprocessor Supervisory Circuits
MAX690A/MAX692A/MAX802L/MAX802M/MAX805L
Microprocessor Supervisory Circuits
________________________________________________________________Maxim Integrated Products1
_________________Pin Configurations
__________Typical Operating Circuit
Call toll free 1-800-998-8800 for free samples or literature.19-4333; Rev 3; 9/93
__________________General DescriptionThe MAX690A/MAX692A/MAX802L/MAX802M/MAX805L
reduce the complexity and number of components
required for power-supply monitoring and battery-control
functions in microprocessor (µP) systems. They signifi-
cantly improve system reliability and accuracy compared
to separate ICs or discrete components.
These parts provide four functions:A reset output during power-up, power-down, and
brownout conditions.Battery-backup switching for CMOS RAM, CMOS
µP, or other low-power logic.A reset pulse if the optional watchdog timer has not
been toggled within 1.6sec.A 1.25V threshold detector for power-fail warning or
low-battery detection, or to monitor a power supply
other than +5V.
The parts differ in their reset-voltage threshold levels
and reset outputs. The MAX690A/MAX802L/MAX805L
generate a reset pulse when the supply voltage drops
below 4.65V, and the MAX692A/MAX802M generate a
reset below 4.40V. The MAX802L/MAX802M guaran-
tee power-fail accuracies to ±2%. The MAX805L is the
same as the MAX690A except that RESET is provided
instead of RESET.
All parts are available in 8-pin DIP and SO packages.
The MAX690A/MAX802L are pin compatible with the
MAX690 and MAX694. The MAX692A/MAX802M are
pin compatible with the MAX692.
_______________________ApplicationsBattery-Powered Computers and Controllers
Intelligent Instruments
Automotive Systems
Critical µP Power Monitoring
___________________________FeaturesPrecision Supply-Voltage Monitor:
4.65V for MAX690A/MAX802L/MAX805L
4.40V for MAX692A/MAX802MReset Time Delay – 200msWatchdog Timer – 1.6sec TimeoutBattery-Backup Power Switching200µA Quiescent Supply Current50nA Quiescent Supply Current in Battery-
Backup ModeVoltage Monitor for Power-Fail or Low-Battery
WarningPower-Fail Accuracy Guaranteed to ±2%
(MAX802L/M)Guaranteed RESET
Assertion to VCC= 1V8-Pin SO and DIP Packages
______________Ordering Information
Ordering Information continued on last page.Dice are specified at TA= +25°C
**Contact factory for availability and processing to MIL-STD-883.
MAX690A/MAX692A/MAX802L/MAX802M/MAX805L
Microprocessor Supervisory CircuitsTerminal Voltage (with respect to GND)
VCC...............................................-0.3V to 6.0V
VBATT..............................................-0.3V to 6.0V
All Other Inputs (Note 1)................-0.3V to (VCC+ 0.3V)
Input Current
VCC......................................................200mA
VBATT.....................................................50mA
GND......................................................20mA
Output Current
VOUT...................Short-Circuit Protected for up to 10sec
All Other Outputs........................................20mA
Rate of Rise, VCC, VBATT................................100V/µs
Continuous Power Dissipation
Plastic DIP (derate 9.09mW/°C above +70°C)........727mW
SO (derate 5.88mW/°C above +70°C)................471mW
CERDIP (derate 8.00mW/°C above +70°C)...........640mW
Operating Temperature Ranges:
MAX69_AC_ _, MAX80_ _ C_ _..................0°C to +70°C
MAX69_AE_ _, MAX80_ _ E_ _................-40°C to +85°C
MAX69_AMJA, MAX805LMJA................-55°C to +125°C
Storage Temperature Range..................-65°C to +160°C
Lead Temperature (soldering, 10sec)..................+300°C
ELECTRICAL CHARACTERISTICS(VCC= 4.75V to 5.5V for MAX690A/MAX802L/MAX805L, VCC= 4.5V to 5.5V for MAX692A/MAX802M, VBATT= 2.8V, = TMINto TMAX, unless otherwise noted.)
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.
ABSOLUTE MAXIMUM RATINGS
Note 1:The input voltage limits on PFIand WDI may be exceeded if the current into these pins is limited to less than 10mA.
MAX690A/MAX692A/MAX802L/MAX802M/MAX805L
Microprocessor Supervisory Circuits
_______________________________________________________________________________________3
Note 2:Either VCCor VBATTcan go to 0V, if the other is greater than 2.0V.
Note 3:"-" = battery-charging current, "+" = battery-discharging current.
Note 4:WDI is guaranteed to be in an intermediate, non-logic level state if WDI is floating and VCCis in the operating voltage range.
WDIis internally biased to 35% of VCCwith an input impedance of 50kΩ.
ELECTRICAL CHARACTERISTICS (continued)(VCC= 4.75V to 5.5V for MAX690A/MAX802L/MAX805L, VCC= 4.5V to 5.5V for MAX692A/MAX802M, VBATT= 2.8V, = TMINto TMAX, unless otherwise noted.)
MAX690A/MAX692A/MAX802L/MAX802M/MAX805L
Microprocessor Supervisory Circuits_______________________________________________________________________________________
__________________________________________Typical Operating Characteristics
MAX805L
RESET OUTPUT VOLTAGE
vs. SUPPLY VOLTAGE500ms/div
VCC
+5V
1V/div
RESET
+5V
1V/div
MAX805L
RESET RESPONSE TIME2μs/div
VCC+4V
+4V
+5V
OUTPUT VOLTAGE
vs. LOAD CURRENT
IOUT (mA)
OUT
(V)
OUTPUT VOLTAGE
vs. LOAD CURRENT
IOUT (mA)
OUT
(V)
MAX690A
RESET OUTPUT VOLTAGE
vs. SUPPLY VOLTAGE
500ms/div
VCC
RESET
+5V
1V/div
+5V
1V/div
MAX690A
RESET RESPONSE TIME2μs/div
VCC
+5V
RESET
+5V
+4V
1V/div
POWER-FAIL COMPARATOR
RESPONSE TIME400ns/div
PFI
+1.30V
PFO
+5V
+0V
+1.2V
POWER-FAIL COMPARATOR
RESPONSE TIME400ns/div
PFI
+1.20V
PFO
+3V
+1.3V
MAX690A/MAX692A/MAX802L/MAX802M/MAX805L
Microprocessor Supervisory Circuits
_______________________________________________________________________________________5
______________________________________________________________Pin Description
MAX690A/MAX692A/MAX802L/MAX802M/MAX805L
_______________Detailed Description
Reset OutputA microprocessor’s (µP’s) reset input starts the µP in a
known state. When the µP is in an unknown state, it should
be held in reset. The MAX690A/MAX692A/MAX802L/
MAX802M assert reset during power-up and prevent code
execution errors during power-down or brownout condi-
tions.
On power-up, once VCCreaches 1V, RESETis guaran-
teed to be a logic low. As VCCrises, RESETremains
low. When VCCexceeds the reset threshold, an internal
timer keeps RESETlow for a time equal to the reset
pulse width; after this interval, RESETgoes high (Figure
2). If a brownout condition occurs (if VCCdips below
the reset threshold), RESETis triggered. Each time
RESETis triggered, it stays low for the reset pulse width
interval. Any time VCCgoes below the reset threshold,
the internal timer restarts the pulse. If a brownout con-
dition interrupts a previously initiated reset pulse, the
reset pulse continues for another 200ms. On power-
down, once VCCgoes below the threshold, RESETis
guaranteed to be logic low until VCCdroops below 1V.
RESETis also triggered by a watchdog timeout. If a
high or low is continuously applied to the WDI pin for
1.6sec,RESETpulses low. As long as RESETis assert-
ed, the watchdog timer remains clear. When RESET
comes high, the watchdog resumes timing and must be
serviced within 1.6sec. If WDI is tied high or low, a
RESETpulse is triggered every 1.8sec (tWDplus tRS).
The MAX805L active-high RESET output is the inverse
of the MAX690A/MAX692A/MAX802L/MAX802M RESET
output, and is guaranteed to be valid with VCCdown to
1.1V. Some µPs, such as Intel’s 80C51, require an
active-high reset pulse.
Watchdog InputThe watchdog circuit monitors the µP’s activity. If the
µP does not toggle the watchdog input (WDI) within
1.6sec, a reset pulse is triggered. The internal 1.6sec
timer is cleared by either a reset pulse or by open cir-
cuiting the WDI input. As long as reset is asserted or
the WDI input is open circuited, the timer remains
cleared and does not count. As soon as reset is
released or WDI is driven high or low, the timer starts
counting. It can detect pulses as short as 50ns.
Power-Fail ComparatorThe PFI input is compared to an internal 1.25V refer-
ence. If PFI is less than 1.25V, PFOgoes low. The
power-fail comparator is intended for use as an under-
voltage detector to signal a failing power supply; it
Microprocessor Supervisory Circuits_______________________________________________________________________________________Figure 1. Block Diagram
Figure 2. Timing Diagram
