MAX705MAX708/MAX813L
Low-Cost, P Supervisory Circuits
________________________________________________________________
Maxim Integrated Products
1
TOP VIEW
1
2
3
4
8
7
6
5
WDO
RESET (RESET)
WDI
PFO
PFI
GND
V
CC
MR
DIP/SO
MAX705
MAX706
MAX813L
1
2
3
4
8
7
6
5
RESET
RESET
N.C.
PFO
PFI
GND
V
CC
MR
DIP/SO
MAX707
MAX708
( ) ARE FOR MAX813L ONLY.
Pin Configurations continued at end of data sheet.
_________________Pin Configurations
V
CC
PFI
MR
PFO
WDO
RESET
UNREGULATED DC
PUSHBUTTON
SWITCH
PFI
I/O LINE
INTERRUPT
P
MAX705
MAX706
MAX813L
MAX667
+5V DC LINEAR
REGULATOR
V
CC
RESET
NMI
__________Typical Operating Circuit
Call toll free 1-800-998-8800 for free samples or literature.
19-4334; Rev. 5; 9/95
_______________General Description
The MAX705-MAX708/MAX813L microprocessor (P)
supervisory circuits reduce the complexity and number
of components required to monitor power-supply and
battery functions in 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 MAX
packages.
_______________________Applications
Computers
Controllers
Intelligent Instruments
Automotive Systems
Critical P Power Monitoring
___________________________Features
o
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--1.6sec Timeout
(MAX705/MAX706)
o
Active-High Reset Output
(MAX707/MAX708/MAX813L)
o
Voltage Monitor for Power-Fail or Low-Battery
Warning
______________Ordering Information
PART
TEMP. RANGE
PIN-PACKAGE
MAX705
CPA
8 Plastic DIP
MAX705CSA
0C to +70C
8 SO
MAX705C/D
0C to +70C
Dice*
Ordering Information continued at end of data sheet.
* Dice are specified at T
A
= +25C.
**Contact factory for availability and processing to MIL-STD-883.
0C to +70C
MAX705CUA
0C to +70C
8 MAX
MAX705MAX708/MAX813L
Low-Cost, P Supervisory Circuits
2
_______________________________________________________________________________________
Terminal Voltage (with respect to GND)
V
CC
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . -0.3V to 6.0V
All Other Inputs (Note 1) . . . . . . . . . . . . . . . -0.3V to (V
CC
+ 0.3V)
Input Current
V
CC
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20mA
GND . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20mA
Output Current (all outputs) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20mA
Continuous Power Dissipation
Plastic DIP (derate 9.09mW/C above +70C) . . . . . . . 727mW
SO (derate 5.88mW/C above +70C) . . . . . . . . . . . . . . . 471mW
MAX (derate 4.10mW/C above +70C) . . . . . . . . . . . . 330mW
CERDIP (derate 8.00mW/C above +70C) . . . . . . . . . . 640mW
Operating Temperature Ranges
MAX70_C__, MAX813LC__ . . . . . . . . . . . . . . . . . . . . 0C to +70C
MAX70_E__, MAX813LE__ . . . . . . . . . . . . . . . . . . . -40C to +85C
MAX70_MJA . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . -55C to +125C
Storage Temperature Range
. . . . . . . . . . . . . . . . -65C to +160C
Lead Temperature (soldering, 10sec)
. . . . . . . . . . . . . . . . +300C
ELECTRICAL CHARACTERISTICS
(V
CC
= 4.75V to 5.5V for MAX705/MAX707/MAX813L, V
CC
= 4.5V to 5.5V for MAX706/MAX708, T
A
= T
MIN
to T
MAX
, 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.
PARAMETER
SYMBOL
CONDITIONS
MIN
TYP
MAX
UNITS
Operating Voltage Range
V
CC
MAX70_C
1.0
5.5
V
MAX813LC
1.1
5.5
MAX70_E/M, MAX813LE/M
1.2
5.5
Reset Threshold (Note 2)
V
RT
MAX705, MAX707, MAX813L
4.50
4.65
4.75
MAX706, MAX708
4.25
4.40
4.50
40
mV
Reset Pulse Width (Note 2)
t
RS
140
200
280
ms
RESET Output Voltage
I
SOURCE
= 800A
V
CC
- 1.5
V
ABSOLUTE MAXIMUM RATINGS
Note 1:
The input voltage limits on PFI and MR can be exceeded if the input current is less than 10mA.
Reset Threshold Hysteresis (Note 2)
I
SINK
= 3.2mA
0.4
0.3
0.3
RESET Output Voltage
MAX707, MAX708, I
SOURCE
= 800A
V
MAX707, MAX708, I
SINK
= 1.2mA
0.4
0.8
0.9
MAX813L
V
CC
- 1.5
0.4
Watchdog Timeout Period
t
WD
MAX705, MAX706, MAX813L
1.00
1.60
2.25
sec
WDI Pulse Width
t
WP
V
IL
= 0.4V, V
IH
= (V
CC
) (0.8)
50
ns
WDI Input Threshold
0.8
V
3.5
MAX70_C, V
CC
= 1V, I
SINK
= 50A
MAX70_E/M, V
CC
= 1.2V, I
SINK
= 100A
MAX813LC, I
SOURCE
= 4A, V
CC
= 1.1V
MAX813LE/M, I
SOURCE
= 4A, V
CC
= 1.2V
I
SOURCE
= 800A
I
SINK
= 3.2mA
Low
High
WDI Input Current
MAX705, MAX706, MAX813L, WDI = V
CC
50
150
A
MAX705, MAX706, MAX813L, WDI = 0V
-150
-50
WDO Output Voltage
V
CC
- 1.5
V
0.4
MAX705, MAX706, MAX813L,
V
CC
= 5V
MAX705, MAX706, MAX813L,
I
SOURCE
= 800A
MAX705, MAX706, MAX813L,
I
SINK
= 1.2mA
V
V
CC
- 1.5
MAX707C, MAX708C
50
350
MAX707E/M, MAX708E/M
50
500
Supply Current
I
SUPPLY
MAX705C, MAX706C, MAX813LC
150
350
A
MAX705E/M, MAX706E/M, MAX813LE/M
150
500
MAX705MAX708/MAX813L
Low-Cost, P Supervisory Circuits
_______________________________________________________________________________________
3
ELECTRICAL CHARACTERISTICS (continued)
(V
CC
= 4.75V to 5.5V for MAX705/MAX707/MAX813L, V
CC
= 4.5V to 5.5V for MAX706/MAX708, T
A
= T
MIN
to T
MAX
, unless otherwise noted.)
PARAMETER
SYMBOL
CONDITIONS
MIN
TYP
MAX
UNITS
0.8
V
2.0
MR Pull-Up Current
MR = 0V
100
250
600
A
MR Pulse Width
t
MR
150
ns
Low
High
MR Input Threshold
MR to Reset Out Delay (Note 2)
t
MD
250
ns
PFI Input Threshold
V
CC
= 5V
1.20
1.25
1.30
V
PFI Input Current
-25.00
0.01
25.00
nA
PFO Output Voltage
I
SOURCE
= 800A
V
CC
- 1.5
V
I
SINK
= 3.2mA
0.4
Note 2:
Applies to both RESET in the MAX705-MAX708 and RESET in the MAX707/MAX708/MAX813L.
MAX705MAX708/MAX813L
Low-Cost, P Supervisory Circuits
4
_______________________________________________________________________________________
__________________________________________Typical Operating Characteristics
MAX707/MAX708/MAX813L
RESET OUTPUT VOLTAGE
vs. SUPPLY VOLTAGE
500ms/div
V
CC
0V
RESET
0V
+5V
1V/div
+5V
1V/div
T
A
= +25C
GND
RESET
V
CC
330pF
10k
MAX813L
RESET RESPONSE TIME
2
s/div
+5V
V
CC
0V
0V
+4V
+4V
GND
RESET
V
CC
330pF
10k
MAX705/MAX707
RESET OUTPUT VOLTAGE
vs. SUPPLY VOLTAGE
500ms/div
V
CC
0V
RESET
0V
+5V
1V/div
+5V
1V/div
V
CC
GND
RESET
V
CC
2k
RESET
330pF
T
A
= +25C
MAX705/MAX707
RESET RESPONSE TIME
2
s/div
V
CC
+5V
RESET
+5V
+4V
1V/div
0V
T
A
= +25C
V
CC
GND
RESET
V
CC
10k
RESET
30pF
POWER-FAIL COMPARATOR
DE-ASSERTION RESPONSE TIME
400ns/div
PFI
+1.20V
PFO
0V
+3V
+1.30V
V
CC
= +5V
T
A
= +25C
+5V
PFO
30pF
1k
+1.25V
PFI
POWER-FAIL COMPARATOR
ASSERTION RESPONSE TIME
400ns/div
PFI
+1.30V
PFO
+5V
0V
+1.20V
1V/div
50mV/div
+5V
PFO
30pF
1k
+1.25V
PFI
V
CC
= +5V
T
A
= +25C
MAX707
RESET, RESET ASSERTION
400ns/div
0V
+5V
RESET
RESET
1V/div
V
CC
= V
RT
T
A
= +25C
+5V
0V
V
CC
GND
RESET
10k
330pF
RESET
10k
330pF
MAX707
RESET, RESET DE-ASSERTION
400ns/div
0V
+5V
RESET
RESET
2V/div
V
CC
= V
RT
T
A
= +25C
+5V
0V
VCC
GND
RESET
RESET
10k
330pF
10k
330pF
MAX705MAX708/MAX813L
Low-Cost, P Supervisory Circuits
_______________________________________________________________________________________
5
______________________________________________________________Pin Description
Watchdog Output pulls low when the internal watch-
dog timer finishes its 1.6sec count and does not go
high again until the watchdog is cleared. WDO also
goes low during low-line conditions. Whenever V
CC
is
below the reset threshold, WDO stays low; however,
unlike RESET, WDO does not have a minimum pulse
width. As soon as V
CC
rises above the reset thresh-
old, WDO goes high with no delay.
Active-High Reset Output is the inverse of RESET.
Whenever RESET is high, RESET is low, and vice
versa (Figure 2). The MAX813L has a RESET output
only.
Active-Low Reset Output pulses low for 200ms when
triggered, and stays low whenever V
CC
is below the
reset threshold (4.65V in the MAX705 and 4.40V in the
MAX706). It remains low for 200ms after V
CC
rises
above the reset threshold or MR goes from low to high
(Figure 3). A watchdog timeout will not trigger RESET
unless WDO is connected to MR.
Watchdog Input. If WDI remains high or low for
1.6sec, the internal watchdog timer runs out and
WDO goes low (Figure 1). Floating WDI or connect-
ing WDI to a high-impedance three-state buffer dis-
ables the watchdog feature. The internal watchdog
timer clears whenever reset is asserted, WDI is three-
stated, or WDI sees a rising or falling edge.
Power-Fail Output goes low and sinks current when
PFI is less than 1.25V; otherwise PFO stays high.
Power-Fail Voltage Monitor Input. When PFI is less
than 1.25V, PFO goes low. Connect PFI to GND or
V
CC
when not used.
FUNCTION
MAX705/MAX706
RESET
7
8
-
WDO
8
-
8
RESET
-
7
7
No Connect
N.C.
-
6
-
WDI
6
-
6
PFO
5
5
5
PFI
4
4
4
0V Ground Reference for all signals
GND
3
3
3
+5V Supply Input
V
CC
2
2
2
NAME
DIP/SO
DIP/SO
DIP/SO
MAX707/MAX708
PIN
-
2
1
-
8
7
6
5
4
MAX
2
-
1
-
-
7
6
5
4
MAX
1
2
-
-
8
7
6
5
4
MAX
MAX813L
Manual-Reset Input triggers a reset pulse when
pulled below 0.8V. This active-low input has an inter-
nal 250A pull-up current. It can be driven from a TTL
or CMOS logic line as well as shorted to ground with
a switch.
MR
1
1
1
3
3
3
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