a
FEATURES
Guaranteed
RESET
Valid with V
CC
= 1 V
190 A Quiescent Current
Precision Supply-Voltage Monitor
4.65 V (ADM705/ADM707)
4.40 V (ADM706/ADM708)
200 ms Reset Pulsewidth
Debounced TTL/CMOS Manual Reset Input (MR)
Independent Watchdog Timer鈥?.6 sec Timeout
(ADM705/ADM706)
Active High Reset Output (ADM707/ADM708)
Voltage Monitor for Power-Fail or Low Battery
Warning
Superior Upgrade for MAX705鈥揗AX708
Also Available in MicroSOIC Packages
APPLICATIONS
Microprocessor Systems
Computers
Controllers
Intelligent Instruments
Critical P Monitoring
Automotive Systems
Critical P Power Monitoring
GENERAL DESCRIPTION
WATCHDOG
INPUT (WDI)
Low Cost P
Supervisory Circuits
ADM705鈥揂DM708
FUNCTIONAL BLOCK DIAGRAMS
WATCHDOG
TRANSITION
DETECTOR
V
CC
250 A
MR
V
CC
4.65V*
POWER-FAIL
INPUT (PFI)
1.25V
RESET
GENERATOR
RESET
WATCHDOG
TIMER
WATCHDOG
OUTPUT (WDO)
RESET &
WATCHDOG
TIMEBASE
ADM705/
ADM706
POWER-FAIL
OUTPUT (PFO)
*VOLTAGE
REFERENCE = 4.65V (ADM705), 4.40V (ADM706)
V
CC
250 A
MR
V
CC
4.65V*
POWER-FAIL
INPUT (PFI)
1.25V
RESET
GENERATOR
RESET
RESET
The ADM705鈥揂DM708 are low cost
碌P
supervisory circuits.
They are suitable for monitoring the 5 V power supply/battery
and can also monitor microprocessor activity.
The ADM705/ADM706 provide the following functions:
1. Power-On Reset output during power-up, power-down and
brownout conditions. The
RESET
output remains opera-
tional with V
CC
as low as 1 V.
2. Independent watchdog timeout,
WDO,
that goes low if the
watchdog input has not been toggled within 1.6 seconds.
3. A 1.25 V threshold detector for power-fail warning, low
battery detection or to monitor a power supply other than
5 V.
4. An active low debounced manual reset input (MR).
The ADM707/ADM708 differ in that:
1. A watchdog timer function is not available.
2. An active high reset output in addition to the active low
output is available.
ADM707/
ADM708
POWER-FAIL
OUTPUT (PFO)
*VOLTAGE
REFERENCE = 4.65V (ADM707), 4.40V (ADM708)
Two supply-voltage monitor levels are available. The ADM705/
ADM707 generate a reset when the supply voltage falls below
4.65 V, while the ADM706/ADM708 require that the supply
fall below 4.40 V before a reset is issued.
All parts are available in 8-lead DIP and SOIC packages. The
ADM707 and ADM708 are also available in space-saving
microSOIC packages.
REV. B
Information furnished by Analog Devices is believed to be accurate and
reliable. However, no responsibility is assumed by Analog Devices for its
use, nor for any infringements of patents or other rights of third parties
which may result from its use. No license is granted by implication or
otherwise under any patent or patent rights of Analog Devices.
One Technology Way, P.O. Box 9106, Norwood, MA 02062-9106, U.S.A.
Tel: 781/329-4700
World Wide Web Site: http://www.analog.com
Fax: 781/326-8703
漏 Analog Devices, Inc., 2000
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