19-0099; Rev 4; 1/06
+3V Voltage Monitoring, Low-Cost µP
Supervisory Circuits
General Description
The MAX706P/R/S/T, MAX706AP/AR/AS/AT, and
MAX708R/S/T microprocessor (µP) supervisory circuits
reduce the complexity and number of components
required to monitor +3V power-supply levels in +3V to
+5V µP systems. These devices significantly improve
system reliability and accuracy compared to separate
ICs or discrete components.
The MAX706P/R/S/T and MAX706AP/AR/AS/AT supervi-
sory circuits provide the following 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 1.6s.
3) A 1.25V threshold detector for power-fail warning,
low-battery detection, or for monitoring a power
supply other than the main supply.
4) An active-low, manual-reset input.
The only difference between the MAX706R/AR,
MAX706S/AS, and MAX706T/AT is the reset-threshold
voltage levels, which are 2.63V, 2.93V, and 3.08V,
respectively. All have active-low reset output signals.
The MAX706P/AP are identical to the MAX706R/AR,
except the reset output signal is active-high. The watch-
dog timer function for the MAX706AP/AR/AS/AT dis-
ables when the WDI input is left open or connected to a
high-impedance state of a low-leakage tri-state output.
The MAX708R/S/T provide the same functions as the
MAX706R/S/T and MAX706AR/AS/AT except they do
not have a watchdog timer. Instead, they provide both
RESET
and RESET outputs. As with the MAX706,
devices with R, S, and T suffixes have reset thresholds
of 2.63V, 2.93V, and 3.08V, respectively.
These devices are available in 8-pin SO, DIP, and
µMAX
®
packages and are fully specified over the oper-
ating temperature range.
♦
µMAX Package, Small 8-Pin SO
♦
Precision Supply-Voltage Monitors
2.63V (MAX706P/R, MAX706AP/AR, and MAX708R)
2.93V (MAX706S, MAX706AS, and MAX708S)
3.08V (MAX706T, MAX706AT, and MAX708T)
♦
200ms Reset Time Delay
♦
Debounced TTL/CMOS-Compatible Manual Reset
Input
♦
100µA Quiescent Current
♦
WDI Disable Feature (MAX706AP/AR/AS/AT)
♦
Watchdog Timer: 1.6s Timeout
♦
Reset Output Signal:
Active-High Only (MAX706P, MAX706AP)
Active-Low Only (MAX706R/S/T, MAX706AR/AS/AT)
Active-High and Active-Low (MAX708R/S/T)
♦
Voltage Monitor for Power-Fail or Low-Battery
Warning
♦
8-Pin Surface-Mount Package
♦
Guaranteed
RESET
Assertion to V
CC
= 1V
Features
MAX706P/R/S/T, MAX706AP/AR/AS/AT, MAX708R/S/T
Ordering Information
PART†
MAX706PCPA
MAX706PCSA
MAX706PCUA
MAX706PEPA
TEMP
RANGE
0°C to +70°C
0°C to +70°C
0°C to +70°C
-40°C to +85°C
PIN-
PACKAGE
8 PDIP
8 SO
8 µMAX
8 PDIP
PKG
CODE
P8-1
S8-2
U8-1
P8-1
†
SO, µMAX, and PDIP packages are available in lead-free.
Ordering Information continued at end of data sheet.
Pin Configurations appear at end of data sheet.
Applications
Battery-Powered Equipment
Portable Instruments
Computers
Controllers
Intelligent Instruments
Critical µP Power Monitoring
UNREGULATED
DC
Typical Operating Circuits
MAX639
DC-DC
CONVERTER
+3V/+3.3V
V
CC
MAX706R/S/T
MAX706AR/AS/AT
V
CC
PFI
PUSHBUTTON
SWITCH
MR
RESET
WDI
WDO
PFO
GND
µP
RESET
I/O LINE
NMI
INTERRUPT
µMAX is a registered trademark of Maxim Integrated Products, Inc.
Typical Operating Circuits continued at end of data sheet.
1
________________________________________________________________
Maxim Integrated Products
For pricing, delivery, and ordering information, please contact Maxim/Dallas Direct! at
1-888-629-4642, or visit Maxim’s website at www.maxim-ic.com.
+3V Voltage Monitoring, Low-Cost µP
Supervisory Circuits
MAX706P/R/S/T, MAX706AP/AR/AS/AT, MAX708R/S/T
ABSOLUTE MAXIMUM RATINGS
Terminal Voltage (with respect to GND)
V
CC
........................................................................-0.3V to +6V
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 (T
A
= +70°C)
8-Pin CERDIP (derate 8mW/°C above +70°C)..............640mW
8-Pin PDIP (derate 9.1mW/°C above +70°C).............727.3mW
8-Pin SO (derate 5.9mW/°C above +70°C)................470.6mW
8-Pin µMAX (derate 4.5mW/
o
C above +70°C) ..............362mW
Operating Temperature Range
MAX70_C .............................................................0°C to +70°C
MAX70_E ..........................................................-40°C to +85°C
MAX70_M .......................................................-55°C to +125°C
Junction Temperature ......................................................+150°C
Storage Temperature Range .............................-65°C to +150°C
Lead Temperature (soldering, 10s) .................................+300°C
Note 1:
The input-voltage limits on PFI, WDI, and
MR
can be exceeded if the input current is less than 10mA.
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.
ELECTRICAL CHARACTERISTICS
(MAX70_P/R, MAX706AP/AR: V
CC
= 2.7V to 5.5V; MAX70_S, MAX706AS: V
CC
= 3.0V to 5.5V; MAX70_T, MAX706AT: V
CC
= 3.15V to
5.5V; T
J
= T
A
= T
MIN
to T
MAX
, unless otherwise noted. Typical values are at T
J
= T
A
= +25°C.) (Note 2)
PARAMETER
Supply Voltage Range
SYMBOL
V
CC
CONDITIONS
MAX70_C
MAX70_E/M
MAX706_C
V
CC
< 3.6V
Supply Current
I
SUPPLY
V
CC
< 5.5V
MAX706_E/M
MAX708_C
MAX708_E/M
MAX706_C
MAX706_E/M
MAX708_C
MAX708_E/M
MAX70_P/R/, MAX706AP/AR
Reset Threshold (Note 3)
(V
CC
Falling)
Reset Threshold Hysteresis
(Note 3)
Reset Pulse Width (Note 3)
RESET OUTPUT
V
OH
V
OL
Output-Voltage High
(MAX70_R/S/T)
(MAX706AR/AS/AT)
V
OH
V
OL
V
OL
V
RST(MAX)
< V
CC
< 3.6V I
SOURCE
= 500µA
V
RST(MAX)
< V
CC
< 3.6V I
SINK
= 1.2mA
4.5V < V
CC
< 5.5V
4.5V < V
CC
< 5.5V
I
RSOURCE
=
800µA
I
SINK
= 3.2mA
V
CC
-
1.5
0.4
0.3
0.3
0.8 x
V
CC
0.3
V
V
RST
MAX70_S, MAX706AS
MAX70_T, MAX706AT
V
HYS
MAX70_P/R/, MAX706AP/AR V
CC
= 3.0V
t
RST
MAX70_S, MAX706AS, V
CC
= 3.3V
V
CC
= 5V
140
140
2.55
2.85
3.00
MIN
1.0
1.2
90
90
50
50
135
135
65
65
2.63
2.93
3.08
20
200
200
200
280
280
ms
TYP
MAX
5.5
5.5
200
300
200
300
350
500
350
500
2.70
3.00
3.15
mV
V
µA
UNITS
V
MAX70_C V
CC
= 1.0V, I
SINK
= 50µA
MAX70_E/M: V
CC
= 1.2V, I
SINK
= 100µA
2
_______________________________________________________________________________________
+3V Voltage Monitoring, Low-Cost µP
Supervisory Circuits
ELECTRICAL CHARACTERISTICS (continued)
(MAX70_P/R, MAX706AP/AR: V
CC
= 2.7V to 5.5V; MAX70_S, MAX706AS: V
CC
= 3.0V to 5.5V; MAX70_T, MAX706AT: V
CC
= 3.15V to
5.5V; T
J
= T
A
= T
MIN
to T
MAX
, unless otherwise noted. Typical values are at T
J
= T
A
= +25°C.) (Note 2)
PARAMETER
SYMBOL
V
OH
Output-Voltage High
(MAX706P) (MAX706AP)
V
OL
V
OH
V
OL
V
OH
Output-Voltage High
(MAX708_)
V
OL
V
OH
V
OL
WATCHDOG INPUT
Watchdog Timeout Period
t
WD
MAX706P/R, MAX706AP/AR, V
CC
= 3.0V
MAX706S/T, MAX706AS/AT, V
CC
= 3.3V
V
RST(MAX)
< V
CC
V
IL
= 0.4V
< 3.6V
4.5V < V
CC
<
V
IH
= 0.8V x V
CC
5.5V
V
RST(MAX)
< V
CC
< 3.6V
V
RST(MAX)
< V
CC
< 3.6V
V
CC
= 5.0V
V
CC
= 5.0V
WDI = 0V or V
CC
MAX706_
MAX706A_
3.5
-1.0
-5
+0.02
+1.0
+5
µA
1.00
1.00
100
ns
50
0.6
0.7 x
V
CC
0.8
V
1.60
1.60
2.25
2.25
s
CONDITIONS
V
RST(MAX)
< V
CC
< 3.6V I
SOURCE
= 215µA
V
RST(MAX)
< V
CC
< 3.6V I
SINK
= 1.2mA
4.5 < V
CC
< 5.5V
4.5V < V
CC
< 5.5V
I
SOURCE
= 800µA
I
SINK
= 3.2mA
V
CC
-
1.5
0.4
0.3
V
0.4
MIN
V
CC
-
0.6
0.3
V
TYP
MAX
UNITS
MAX706P/R/S/T, MAX706AP/AR/AS/AT, MAX708R/S/T
V
RST(MAX)
< V
CC
< 3.6V I
SOURCE
= 500µA 0.8 x V
CC
V
RST(MAX)
< V
CC
< 3.6V I
SINK
= 500µA
4.5V < V
CC
< 5.5V
4.5V < V
CC
< 5.5V
I
SOURCE
= 800µA
I
SINK
= 1.2mA
V
CC
-
1.5
WDI Pulse Width
(MAX706_, MAX706A_)
t
WP
V
IL
Watchdog Input Threshold
(MAX706_, MAX706A_)
V
IH
V
IL
V
IH
WDI Input Current
_______________________________________________________________________________________
3
+3V Voltage Monitoring, Low-Cost µP
Supervisory Circuits
MAX706P/R/S/T, MAX706AP/AR/AS/AT, MAX708R/S/T
ELECTRICAL CHARACTERISTICS (continued)
(MAX70_P/R, MAX706AP/AR: V
CC
= 2.7V to 5.5V; MAX70_S, MAX706AS: V
CC
= 3.0V to 5.5V; MAX70_T, MAX706AT: V
CC
= 3.15V to
5.5V; T
J
= T
A
= T
MIN
to T
MAX
, unless otherwise noted. Typical values are at T
J
= T
A
= +25°C.) (Note 2)
PARAMETER
WATCHDOG OUTPUT
V
OH
WDO
Output Voltage
(MAX706_, MAX706A_)
V
OL
V
OH
V
OL
MANUAL RESET INPUT
V
RST(MAX)
< V
CC
< 3.6V
4.5V < V
CC
<
5.5V
MR
Pulse Width
t
MR
V
IL
MR
Input Threshold
V
IH
V
IL
V
IH
MR
to Reset Output Delay
POWER-FAILURE COMPARATOR
(MAX70_P/R, MAX706AP/AR) PFI falling
V
CC
= 3.0V
(MAX70_S/T, MAX706AS/AT) PFI falling,
V
CC
= 3.3V
PFI Input Current
V
OH
PFO
Output Voltage
V
OL
V
OH
V
OL
V
RST(MAX)
< V
CC
< 3.6V I
SOURCE
= 500µA
V
RST(MAX)
< V
CC
< 3.6V I
SINK
= 1.2mA
4.5V < V
CC
< 5.5V
4.5V < V
CC
< 5.5V
I
SOURCE
= 800µA
I
SINK
= 3.2mA
V
CC
-
1.5
0.4
1.20
1.20
-25
0.8 x
V
CC
0.3
V
1.25
1.25
+0.01
1.30
V
1.30
+25
nA
t
MD
V
RST(MAX)
< V
CC
< 3.6V
4.5V < V
CC
< 5.5V
V
RST(MAX)
< V
CC
< 3.6V
V
RST(MAX)
< V
CC
< 3.6V
4.5V < V
CC
< 5.5V
4.5V < V
CC
< 5.5V
V
RST(MAX)
< V
CC
< 3.6V
4.5V < V
CC
< 5.5V
2.0
750
250
ns
0.7 x
V
CC
0.8
25
100
500
150
0.6
V
70
250
250
µA
600
ns
V
RST(MAX)
< V
CC
< 3.6V I
SOURCE
= 500µA
V
RST(MAX)
< V
CC
< 3.6V I
SINK
= 500µA
4.5V < V
CC
< 5.5V
4.5V < V
CC
< 5.5V
I
SOURCE
= 800µA
I
SINK
= 1.2mA
V
CC
-
1.5
0.4
0.8 x
V
CC
0.3
V
SYMBOL
CONDITIONS
MIN
TYP
MAX
UNITS
MR
Pullup Current
MR
= 0
PFI Input Threshold
Note 2:
All devices 100% production tested at T
A
= +85°C. Limits over temperature are guaranteed by design.
Note 3:
Applies to both
RESET
in the MAX70_R/S/T and MAX706AR/AS/AT, and RESET in the MAX706P/MAX706AP.
4
_______________________________________________________________________________________
+3V Voltage Monitoring, Low-Cost µP
Supervisory Circuits
MAX706P/R/S/T, MAX706AP/AR/AS/AT, MAX708R/S/T
Typical Operating Characteristics
(T
A
= +25°C, unless otherwise noted.)
_______________________________________________________________________________________
5
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