MAX813LCSA ,Low-Cost / uP Supervisory CircuitsApplicationsComputers_________________Pin ConfigurationsControllersIntelligent Instruments TOP VIEW ..
MAX813LCSA ,Low-Cost / uP Supervisory CircuitsELECTRICAL CHARACTERISTICS(V = 4.75V to 5.5V for MAX705/MAX707/MAX813L, V = 4.5V to 5.5V for MAX706 ..
MAX813LCSA+ ,Low-Cost, µP Supervisory CircuitsMAX705–MAX708/MAX813L Low-Cost, μP Supervisory Circuits
MAX813LCSA+T ,Low-Cost, µP Supervisory CircuitsElectrical Characteristics(V = 4.75V to 5.5V for MAX705/MAX707/MAX813L, V = 4.5V to 5.5V for MAX706 ..
MAX813LCUA ,Low-Cost / uP Supervisory CircuitsFeaturesThe MAX705-MAX708/MAX813L microprocessor (µP) ' µMAX Package: Smallest 8-Pin SOsupervisory ..
MAX813LEPA ,Low-Cost / uP Supervisory CircuitsMAX705–MAX708/MAX813L19-4334; Rev. 5; 9/95Low-Cost, µP Supervisory Circuits_______________
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MB81C81A-35 ,CMOS 256K-BIT HIGH-SPEED SRAMMay 1990 00
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MB81F643242C-10FN ,4 x 512K x 32 bit synchronous dynamic RAMFUJITSU SEMICONDUCTORADVANCED INFO. AE0.1EDATA SHEETMEMORYCMOS4 · 512 K · 32 BITSYNCHRONOUS DYNAMIC ..
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MAX813LCPA-MAX813LCSA-MAX813LCUA-MAX813LEPA-MAX813LESA-MAX813LMJA
Low-Cost / uP Supervisory Circuits
MAX705–MAX708/MAX813L
Low-Cost, µP Supervisory Circuits
_________________Pin Configurations
__________Typical Operating Circuit19-4334; Rev. 5; 9/95
_______________General DescriptionThe MAX705-MAX708/MAX813L microprocessor (µP)
supervisory circuits reduce the complexity and number
of components required to monitor power-supply and
battery functions in µP systems. These devices signifi-
cantly improve system reliability and accuracy com-
pared to separate ICs or discrete components.
The MAX705/MAX706/MAX813L provide four functions:A reset output during power-up, power-down, and
brownout conditions.An independent watchdog output that goes low if
the watchdog input has not been toggled within 1.6
seconds.A 1.25V threshold detector for power-fail warning,
low-battery detection, or for monitoring a power sup-
ply other than +5V.An active-low manual-reset input.
The MAX707/MAX708 are the same as the MAX705/
MAX706, except an active-high reset is substituted for
the watchdog timer. The MAX813L is the same as the
MAX705, except RESET is provided instead of RESET.
Two supply-voltage monitor levels are available: The
MAX705/MAX707/MAX813L generate a reset pulse when
the supply voltage drops below 4.65V, while the
MAX706/MAX708 generate a reset pulse below 4.40V.
All four parts are available in 8-pin DIP, SO and µMAX
packages.
_______________________ApplicationsComputers
Controllers
Intelligent Instruments
Automotive Systems
Critical µP Power Monitoring
___________________________FeaturesµMAX Package: Smallest 8-Pin SOGuaranteed RESETValid at VCC= 1VPrecision Supply-Voltage Monitor
4.65V in MAX705/MAX707/MAX813L
4.40V in MAX706/MAX708200ms Reset Pulse WidthDebounced TTL/CMOS-Compatible
Manual-Reset InputIndependent Watchdog Timer—1.6sec Timeout
(MAX705/MAX706)Active-High Reset Output
(MAX707/MAX708/MAX813L)Voltage Monitor for Power-Fail or Low-Battery
Warning
______________Ordering Information
Ordering Information continued at end of data sheet.Dice are specified at TA= +25°C.
**Contact factory for availability and processing to MIL-STD-883.
MAX705–MAX708/MAX813L
Low-Cost, µP Supervisory CircuitsTerminal Voltage (with respect to GND)
VCC..............................................-0.3V to 6.0V
All Other Inputs (Note 1)...............-0.3V to (VCC+ 0.3V)
Input Current
VCC......................................................20mA
GND....................................................20mA
Output Current (all outputs).............................20mA
Continuous Power Dissipation
Plastic DIP(derate 9.09mW/°C above +70°C).......727mW(derate 5.88mW/°C above +70°C)...............471mW
µMAX (derate 4.10mW/°C above +70°C)............330mW
CERDIP (derate 8.00mW/°C above +70°C)..........640mW
Operating Temperature Ranges
MAX70_C__, MAX813LC__....................0°C to +70°C
MAX70_E__, MAX813LE__...................-40°C to +85°C
MAX70_MJA................................-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 MAX705/MAX707/MAX813L, VCC= 4.5V to 5.5V for MAX706/MAX708, TA= 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 PFI and MRcan be exceeded if the input current is less than 10mA.
MAX705–MAX708/MAX813L
Low-Cost, µP Supervisory Circuits
ELECTRICAL CHARACTERISTICS (continued)(VCC= 4.75V to 5.5V for MAX705/MAX707/MAX813L, VCC= 4.5V to 5.5V for MAX706/MAX708, TA= TMINto TMAX, unless otherwise noted.)
Note 2:Applies to both RESETin the MAX705-MAX708 and RESET in the MAX707/MAX708/MAX813L.
MAX705–MAX708/MAX813L
Low-Cost, µP Supervisory Circuits
__________________________________________Typical Operating Characteristics
MAX707/MAX708/MAX813L
RESET OUTPUT VOLTAGE
vs. SUPPLY VOLTAGE500ms/div
VCC
RESET
+5V
1V/div
+5V
1V/div
MAX813L
RESET RESPONSE TIME2μs/div
+5V
VCC
+4V
+4V
MAX705/MAX707
RESET OUTPUT VOLTAGE
vs. SUPPLY VOLTAGE500ms/div
VCC
RESET
+5V
1V/div
+5V
1V/div
MAX705/MAX707
RESET RESPONSE TIME2μs/div
VCC
+5V
RESET
+5V
+4V
1V/div
POWER-FAIL COMPARATOR
DE-ASSERTION RESPONSE TIME400ns/div
PFI
+1.20V
PFO
+3V
+1.30V
POWER-FAIL COMPARATOR
ASSERTION RESPONSE TIME400ns/div
PFI
+1.30V
PFO
+5V
+1.20V
1V/div
50mV/div
MAX707
RESET, RESET ASSERTION400ns/div
+5V
RESET
RESET
1V/div
+5V
MAX707
RESET, RESET DE-ASSERTION400ns/div
+5V
RESET
RESET
2V/div
+5V
MAX705–MAX708/MAX813L
Low-Cost, µP Supervisory Circuits
______________________________________________________________Pin Description
MAX705–MAX708/MAX813L
_______________Detailed Description
Reset OutputA microprocessor’s (µP’s) reset input starts the µP in a
known state. Whenever the µP is in an unknown state, it
should be held in reset. The MAX705-MAX708/MAX813L
assert reset during power-up and prevent code execu-
tion errors during power-down or brownout conditions.
On power-up, once VCCreaches 1V, RESETis a guaran-
teed logic low of 0.4V or less. As VCCrises, RESETstays
low. When VCCrises above the reset threshold, an inter-
nal timer releases RESETafter about 200ms. RESETpuls-
es low whenever VCCdips below the reset threshold, i.e.
brownout condition. If brownout occurs in the middle of
a previously initiated reset pulse, the pulse continues for
at least another 140ms. On power-down, once VCCfalls
below the reset threshold, RESETstays low and is guar-
anteed to be 0.4V or less until VCCdrops below 1V.
The MAX707/MAX708/MAX813L active-high RESEToutput
is simply the complement of the RESEToutput, 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 TimerThe MAX705/MAX706/MAX813L watchdog circuit moni-
tors the µP’s activity. If the µP does not toggle the watch-
dog input (WDI) within 1.6sec and WDI is not three-stat-
ed, WDOgoes low. As long as RESETis asserted or the
WDI input is three-stated, the watchdog timer will stay
cleared and will not count. As soon as reset is released
and WDI is driven high or low, the timer will start counting.
Pulses as short as 50ns can be detected.
Typically, WDOwill be connected to the non-maskable
interrupt input (NMI) of a µP. When VCCdrops below
the reset threshold, WDOwill go low whether or not the
watchdog timer has timed out yet. Normally this would
trigger an NMI interrupt, but RESETgoes low simultane-
ously, and thus overrides the NMI interrupt.
If WDI is left unconnected, WDOcan be used as a low-
line output. Since floating WDI disables the internal
timer, WDOgoes low only when VCCfalls below the
reset threshold, thus functioning as a low-line output.
The MAX705/MAX706 have a watchdog timer and a
RESEToutput. The MAX707/MAX708 have both active-
high and active-low reset outputs. The MAX813L has
both an active-high reset output and a watchdog timer.
Manual ResetThe manual-reset input (MR) allows reset to be trig-
gered by a pushbutton switch. The switch is effectively
debounced by the 140ms minimum reset pulse width.is TTL/CMOS logic compatible, so it can be driven
by an external logic line. MRcan be used to force a
watchdog timeout to generate a reset pulse in the
MAX705/MAX706/MAX813L. Simply connect WDOto
MR.
Low-Cost, µP Supervisory CircuitsFigure 1. MAX705/MAX706/MAX813L Block Diagram
Figure 2. MAX707/MAX708 Block Diagram
