19-4334; Rev. 5; 9/95
Low-Cost, 碌P Supervisory Circuits
_______________General Description
The MAX705-MAX708/MAX813L microprocessor (碌P)
supervisory circuits reduce the complexity and number
of components required to monitor power-supply and
battery functions in 碌P 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:
1) A reset output during power-up, power-down, and
brownout conditions.
2) An independent watchdog output that goes low if
the watchdog input has not been toggled within 1.6
seconds.
3) A 1.25V threshold detector for power-fail warning,
low-battery detection, or for monitoring a power sup-
ply other than +5V.
4) 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 碌MAX
packages.
___________________________Features
o
碌MAX Package: Smallest 8-Pin SO
o
Guaranteed RESET Valid at V
CC
= 1V
o
Precision Supply-Voltage Monitor
4.65V in MAX705/MAX707/MAX813L
4.40V in MAX706/MAX708
o
200ms Reset Pulse Width
o
Debounced TTL/CMOS-Compatible
Manual-Reset Input
o
Independent Watchdog Timer鈥?.6sec Timeout
(MAX705/MAX706)
o
Active-High Reset Output
(MAX707/MAX708/MAX813L)
o
Voltage Monitor for Power-Fail or Low-Battery
Warning
MAX705鈥揗AX708/MAX813L
______________Ordering Information
PART
MAX705CPA
MAX705CSA
MAX705CUA
MAX705C/D
TEMP. RANGE
0掳C to +70掳C
0掳C to +70掳C
0掳C to +70掳C
0掳C to +70掳C
PIN-PACKAGE
8 Plastic DIP
8 SO
8 碌MAX
Dice*
_______________________Applications
Computers
Controllers
Intelligent Instruments
Automotive Systems
Critical 碌P Power Monitoring
Ordering Information continued at end of data sheet.
* Dice are specified at T
A
= +25掳C.
**Contact factory for availability and processing to MIL-STD-883.
_________________Pin Configurations
TOP VIEW
MR
V
CC
1
2
8
7
WDO
RESET (RESET)
WDI
PFO
GND
3
__________Typical Operating Circuit
UNREGULATED DC
PFI
4
MAX705
MAX706
MAX813L
DIP/SO
6
5
MAX667
+5V DC LINEAR
REGULATOR
碌P
V
CC
PFI
MR
RESET
PFI
MAX705
WDO
MAX706
PFO
V
CC
RESET
I/O LINE
NMI
INTERRUPT
MR
V
CC
1
2
8
7
RESET
RESET
N.C.
PFO
GND
3
PFI
4
MAX707
MAX708
6
5
PUSHBUTTON
SWITCH
MAX813L
DIP/SO
( ) ARE FOR MAX813L ONLY.
Pin Configurations continued at end of data sheet.
________________________________________________________________
Maxim Integrated Products
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