19-0099; Rev 5; 4/06
+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.
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