MAX6824LUK-T ,4.63 V, low-power mP supervisor with manual reset and watchdog timerMAX6821–MAX682519-1868; Rev 1; 1/01Low-Voltage SOT23 µP Supervisors withManual Reset and Watchdog T ..
MAX6825VUK-T ,1.58 V, low-power mP supervisor with manual reset and watchdog timerApplications MAX6824_UK-T -40°C to +125°C 5 SOT23-5 MAX6825 _UK-T -40°C to +125°C 5 SOT23-5 Set- ..
MAX6826LUT+ ,Dual, Ultra-Low-Voltage SOT23 µP Supervisors with Manual Reset and Watchdog TimerMAX6826–MAX683119-1867; Rev 1; 1/02Dual Ultra-Low-Voltage SOT23 µP Supervisorswith Manual Reset and ..
MAX6826LUT+T ,Dual, Ultra-Low-Voltage SOT23 µP Supervisors with Manual Reset and Watchdog TimerELECTRICAL CHARACTERISTICS(V = +4.5V to +5.5V for MAX68_ _L/M, V = +2.7V to +3.6V for MAX68_ _T/S/R ..
MAX6829SFUT+T ,Dual, Ultra-Low-Voltage SOT23 µP Supervisors with Manual Reset and Watchdog TimerApplicationsMAX6828 _UT-T -40°C to +125°C 6 SOT23-6 Portable/Battery- Automotive Systems MAX6829_ _ ..
MAX6829TIUT-T ,Dual, Ultra-Low-Voltage SOT23 µP Supervisors with Manual Reset and Watchdog TimerFeaturesThe MAX6826–MAX6831 are ultra-low-voltage micro- Monitor Primary V Supplies from +1.8V CCp ..
MB3793-27APNF ,Power Voltage Monitoring IC with Watchdog TimerApplicationsBIPOLARPower Voltage Monitoring ICwith Watchdog TimerMB3793-27An DESCRIPTIONThe MB3793 ..
MB3793-27APNF ,Power Voltage Monitoring IC with Watchdog TimerFEATURES• Precise detection of power voltage fall: – 2.5%• Detection voltage with hysteresis• Low p ..
MB3793-42PNF , POWER-VOLTAGE MONITORING IC WITH WATCHDOG TIMER
MB3800 ,Switching Regulator Controller (Low Voltage)FEATURES• Wide supply voltage operating range: 1.8 to 15 V• Low current consumption: Typically 5.5 ..
MB3800PFV ,Switching Regulator Controller (Low Voltage)FUJITSU SEMICONDUCTORDS04-27212-2EDATA SHEETASSP For Power Supply
MB3800PNF ,Switching Regulator Controller (Low Voltage)ApplicationsBIPOLARSwitching Regulator Controller(Low Voltage)MB3800n DESCRIPTIONThe MB3800 is a si ..
MAX6821MUK-T-MAX6821RUK-T-MAX6822MUK-T-MAX6822WUK-T-MAX6823TUK-T-MAX6824LUK-T-MAX6825VUK-T
4.63 V, low-power mP supervisor with manual reset and watchdog timer
General DescriptionThe MAX6821–MAX6825 are low-voltage microprocessor
(µP) supervisory circuits that combine voltage monitor-
ing, watchdog timer, and manual reset input functions in
a 5-pin SOT23 package. Microprocessor supervisory cir-
cuits significantly improve system reliability and accura-
cy compared to separate ICs or discrete components.
These devices assert a reset signal whenever the moni-
tored voltage drops below its preset threshold, keeping it
asserted for a minimum timeout period after VCCrises
above the threshold. In addition, a watchdog timer moni-
tors against code execution errors. A debounced manual
reset is also available. The MAX6821–MAX6825 monitor
voltages from +1.8V to +5.0V. These outputs are guaran-
teed to be in the correct state for VCCdown to +1.0V.
Nine preprogrammed reset threshold voltages are
available (see Threshold Suffix Guide). The MAX6821,
MAX6822, and MAX6823 all have a manual reset input
and a watchdog timer. The MAX6821 has push-pull
RESET, the MAX6822 has open-drain RESET, and the
MAX6823 has push-pull RESET. The MAX6824 has a
watchdog timer and both push-pull RESETand push-
pull RESET. The MAX6825 has a manual reset input
and both push-pull RESETand push-pull RESET. The
Selector Guide explains the functions offered in this
series of parts.
________________________Applications
FeaturesMonitors +1.8V, +2.5V, +3.0V, +3.3V, +5.0V
Supplies140ms (min) Reset Timeout Delay1.6s Watchdog Timeout Period
(MAX6821/MAX6822/MAX6823/MAX6824)Manual Reset Input
(MAX6821/MAX6822/MAX6823/MAX6825)Three Reset Output Options
Push-Pull RESET
Push-Pull RESET
Open-Drain RESETGuaranteed Reset Valid to VCC= +1.0VImmune to Short Negative VCCTransientsNo External ComponentsSmall 5-Pin SOT23 Packages
MAX6821–MAX6825
Low-Voltage SOT23 µP Supervisors with
Manual Reset and Watchdog Timer
Pin Configurations19-1868; Rev 1; 1/01
Ordering Information
Threshold Suffix Guide*Insert the desired suffix letter (from the table below) into the blank
to complete the part number.
available for standard versions only. All parts require a 2.5k
minimum order increment. Contact factory for availability.
Typical Operating Circuit appears at end of data sheet.
Selector Guide appears at end of data sheet.Set-Top Boxes
Computers and
Controllers
Embedded Controllers
Intelligent Instruments
Automotive Systems
Critical µP Monitoring
Portable/Battery-
Powered Equipment
MAX6821–MAX6825
Low-Voltage SOT23 µP Supervisors with
Manual Reset and Watchdog Timer
ABSOLUTE MAXIMUM RATINGS
ELECTRICAL CHARACTERISTICS(VCC= +4.5V to +5.5V for MAX682_L/M, VCC= +2.7V to +3.6V for MAX682_T/S/R, VCC= +2.1V to +2.75V for MAX682_Z/Y, VCC=
+1.53V to +2.0V for MAX682_W/V, TA= -40°C to +125°C, unless otherwise specified. Typical values are at TA= +25°C.) (Note 1)
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.
VCCto GND...........................................................-0.3V to +6.0V
Open-Drain RESET................................................-0.3V to +6.0V
Push-Pull RESET, RESET, MR, WDI...........-0.3V to (VCC+ 0.3V)
Input Current (VCC).............................................................20mA
Output Current (RESET, RESET).........................................20mA
Continuous Power Dissipation (TA= +70°C)
5-Pin SOT23 (derate 7.1mW/°C above +70°C)............571mW
Operating Temperature Range.........................-40°C to +125°C
Junction Temperature......................................................+150°C
Storage Temperature Range.............................-65°C to +150°C
Lead Temperature (soldering, 10s).................................+300°C
MAX6821–MAX6825
Low-Voltage SOT23 µP Supervisors with
Manual Reset and Watchdog Timer
ELECTRICAL CHARACTERISTICS (continued)(VCC= +4.5V to +5.5V for MAX682_L/M, VCC= +2.7V to +3.6V for MAX682_T/S/R, VCC= +2.1V to +2.75V for MAX682_Z/Y, VCC=
+1.53V to +2.0V for MAX682_W/V, TA= -40°C to +125°C, unless otherwise specified. Typical values are at TA= +25°C.) (Note 1)
MAX6821–MAX6825
Low-Voltage SOT23 µP Supervisors with
Manual Reset and Watchdog Timer
Typical Operating Characteristics(TA = +25°C, unless otherwise noted.)
MAX6821–MAX6825
Low-Voltage SOT23 µP Supervisors with
Manual Reset and Watchdog Timer
RESET/RESET OutputA µP’s reset input starts the µP in a known state. The
MAX6821–MAX6825 µP supervisory circuits assert a
reset to prevent code-execution errors during power-
up, power-down, and brownout conditions. Whenever
VCCfalls below the reset threshold, the reset output
asserts low for RESETand high for RESET. Once VCC
exceeds the reset threshold, an internal timer keeps the
reset output asserted for the specified reset timeout
period (tRP); after this interval, reset output returns to its
original state (see Figure 2).
Manual Reset InputMany µP-based products require manual reset capabil-
ity, allowing the operator, a test technician, or external
logic circuitry to initiate a reset. On the MAX6821/
MAX6822/MAX6823/MAX6825, a logic low on MR
asserts a reset. Reset remains asserted while MR is
low, and for the timeout period (140ms min) after it
so it can be left open if not used. This input can be dri-
ven with CMOS logic levels or with open-drain/collector
outputs. Connect a normally open momentary switch
from MRto GND to create a manual reset function;
external debounce circuitry is not required. If MRis dri-
ven from long cables or the device is used in a noisy
environment, connect a 0.1µF capacitor from MRto
GND to provide additional noise immunity.
Watchdog InputIn the MAX6821–MAX6824, the watchdog circuit moni-
tors the µP’s activity. If the µP does not toggle (low to
high or high to low) the watchdog input (WDI) within the
watchdog timeout period (1.6s nominal), reset asserts
for the reset timoeout period. The internal 1.6s timer
can be cleared by either a reset pulse or by toggling
WDI. The WDI can detect pulses as short as 50ns.
While reset is asserted, the timer remains cleared and
does not count. As soon as reset is released, the timer
starts counting (see Figure 3).
Disable the watchdog function by leaving WDI uncon-
nected or by three-stating the driver connected to WDI.
The watchdog input is internally driven low during the
first 7/8 of the watchdog timeout period and high for the
last 1/8 of the watchdog timeout period. When WDI is left
unconnected, this internal driver clears the 1.6s timer
every 1.4s. When WDI is three-stated or unconnected,
the maximum allowable leakage current is 10µA and the
maximum allowable load capacitance is 200pF.
Applications Information
Watchdog Input CurrentThe MAX6821/MAX6822/MAX6823/MAX6824 WDI inputs
are internally driven through a buffer and series resistor
from the watchdog timer (Figure 1). When WDI is left
unconnected, the watchdog timer is serviced within the
watchdog timeout period by a low-high-low pulse from
the counter chain. For minimum watchdog input current
(minimum overall power consumption), leave WDI low for
the majority of the watchdog timeout period, pulsing it
low-high-low once within the first 7/8 of the watchdog
timeout period to reset the watchdog timer. If WDI is
externally driven high for the majority of the timeout peri-
od, up to 160µA can flow into WDI.
Interfacing to µPs with
Bidirectional Reset PinsSince the RESEToutput on the MAX6822 is open drain,
it interfaces easily with µPs that have bidirectional reset
pins, such as the Motorola 68HC11. Connecting the µP
supervisor’s RESEToutput directly to the microcon-
troller’s RESETpin with a single pullup resistor allows
either device to assert reset (see Figure 4).
Negative-Going VCCTransientsThese supervisors are relatively immune to short-dura-
tion, negative-going VCCtransients (glitches), which
usually do not require the entire system to shut down.
MAX6821–MAX6825
Low-Voltage SOT23 µP Supervisors with
Manual Reset and Watchdog TimerFigure 1. Functional Diagram
