MAX800MCPE Maxim Integrated Products, MAX800MCPE Datasheet - Page 15
![IC MPU SUPERVISORY CIRCUIT 16DIP](/photos/6/57/65728/175-16-dip_sml.jpg)
MAX800MCPE
Manufacturer Part Number
MAX800MCPE
Description
IC MPU SUPERVISORY CIRCUIT 16DIP
Manufacturer
Maxim Integrated Products
Type
Battery Backup Circuitr
Datasheet
1.MAX691ACPE.pdf
(17 pages)
Specifications of MAX800MCPE
Number Of Voltages Monitored
1
Output
Open Drain, Push-Pull
Reset
Active High/Active Low
Reset Timeout
140 ms Minimum
Voltage - Threshold
4.4V
Operating Temperature
0°C ~ 70°C
Mounting Type
Through Hole
Package / Case
16-DIP (0.300", 7.62mm)
Monitored Voltage
0 V to 5.5 V
Output Type
Active High, Active Low, Open Drain
Manual Reset
Not Resettable
Watchdog
Watchdog
Battery Backup Switching
Backup
Supply Voltage (max)
5.5 V
Supply Voltage (min)
0 V
Supply Current (typ)
100 uA
Maximum Power Dissipation
842 mW
Maximum Operating Temperature
+ 70 C
Mounting Style
Through Hole
Minimum Operating Temperature
0 C
Power Fail Detection
Yes
Lead Free Status / RoHS Status
Contains lead / RoHS non-compliant
The V
the battery switchover comparator and should not
exceed 0.03V/µs. A standard rule of thumb for filter
capacitance on most regulators is on the order of 100µF
per amp of current. When the power supply is shut off or
the main battery is disconnected, the associated initial
V
The V
nentially, which more than satisfies the maximum fall-time
requirement.
A way to help the watchdog timer keep a closer watch
on software execution involves setting and resetting the
watchdog input at different points in the program,
rather than “pulsing” the watchdog input high-low-high
or low-high-low. This technique avoids a “stuck” loop
where the watchdog timer continues to be reset within
the loop, keeping the watchdog from timing out. Figure
14 shows an example flow diagram where the I/O dri-
ving the watchdog input is set high at the beginning of
the program, set low at the beginning of every subrou-
tine or loop, then set high again when the program
returns to the beginning. If the program should “hang”
in any subroutine, the I/O is continually set low and the
watchdog timer is allowed to time out, causing a reset
or interrupt to be issued.
CC
fall rate is just the inverse or 1A/100µF = 0.01V/µs.
CC
CC
fall rate decreases with time as V
fall time is limited by the propagation delay of
Watchdog Software Considerations
______________________________________________________________________________________
Maximum V
Microprocessor Supervisory Circuits
CC
CC
Fall Time
falls expo-
Figure 14. Watchdog Flow Diagram
OR PROGRAM LOOP
SUBROUTINE
SET WDI
RETURN
START
LOW
HIGH
END
WDI
SET
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