MAX801NEPA Maxim Integrated, MAX801NEPA Datasheet - Page 12
MAX801NEPA
Manufacturer Part Number
MAX801NEPA
Description
Supervisory Circuits
Manufacturer
Maxim Integrated
Series
MAX801L, MAX801M, MAX801N, MAX808L, MAX808M, MAX808Nr
Datasheet
1.MAX801LESA.pdf
(12 pages)
Specifications of MAX801NEPA
Number Of Voltages Monitored
1
Monitored Voltage
0 V to 5.5 V
Undervoltage Threshold
4.5 V
Overvoltage Threshold
4.65 V
Output Type
Active High, Active Low, Push-Pull
Manual Reset
Not Resettable
Watchdog
Watchdog
Battery Backup Switching
Backup
Power-up Reset Delay (typ)
280 ms
Supply Voltage - Max
5.5 V
Maximum Operating Temperature
+ 85 C
Mounting Style
Through Hole
Package / Case
PDIP N
Chip Enable Signals
No
Maximum Power Dissipation
727 mW
Minimum Operating Temperature
- 40 C
Power Fail Detection
No
Supply Current (typ)
68 uA
Supply Voltage - Min
0 V
To help the watchdog timer keep a closer watch on
software execution, you can set and reset the watch-
dog 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 9 shows a sample flow diagram where the I/O
driving the watchdog input is set high at the beginning
of the program, low at the beginning of every subrou-
tine or loop, then high again when the program returns
to the beginning. If the program should “hang” in any
subroutine, the I/O would be continually set low and the
watchdog timer would be allowed to time out, causing a
reset or interrupt to be issued.
The V
the battery switchover comparator and should not
exceed 0.03V/µs. A standard rule for filter capacitance
on most regulators is around 100µF per Ampere of cur-
rent. When the power supply is shut off or the main bat-
tery is disconnected, the associated initial V
is just the inverse, or 1A/100µF = 0.01V/µs.
Maxim cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in a Maxim product. No circuit patent licenses are
implied. Maxim reserves the right to change the circuitry and specifications without notice at any time.
12
© 2005 Maxim Integrated Products
8-Pin µP Supervisory Circuits
with ±1.5% Reset Accuracy
_________________Pin Configurations
__________________Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 (408) 737-7600
CC
TOP VIEW
fall time is limited by the propagation delay of
Watchdog Software Considerations
LOWLINE
LOWLINE
RESET
RESET
GND
GND
V
V
CC
CC
1
2
3
4
1
2
3
4
DIP/SO
DIP/SO
Maximum V
MAX808
MAX801
8
7
6
5
8
7
6
5
OUT
BATT
CE IN
CE OUT
OUT
BATT
WDI
RESET
Printed USA
CC
Fall Time
CC
fall rate
Figure 9. Watchdog Flow Diagram
TRANSISTOR COUNT: 922
___________________Chip Information
is a registered trademark of Maxim Integrated Products, Inc.
OR PROGRAM LOOP,
SUBROUTINE
SET WDI
RETURN
START
HIGH
LOW
WDI
END
SET