Low Cost Microprocessor
Supervisory Circuits
ADM705/ADM706/ADM707/ADM708
Data Sheet
FUNCTIONAL BLOCK DIAGRAMS
Guaranteed RESET valid with VCC = 1 V
190 μA quiescent current
Precision supply voltage monitor
4.65 V (ADM705/ADM707)
4.40 V (ADM706/ADM708)
200 ms reset pulse width
Debounced TTL/CMOS manual reset input (MR)
Independent watchdog timer (ADM705/ADM706)
1.60 sec timeout (ADM705/ADM706)
Active high reset output (ADM707/ADM708)
Voltage monitor for power fail or low battery warning
Superior upgrade for MAX705 to MAX708
WATCHDOG
INPUT (WDI)
WATCHDOG
TRANSITION
DETECTOR
VCC
250μA
MR
WATCHDOG
TIMER
RESET AND
WATCHDOG
TIMEBASE
RESET
GENERATOR
VCC
4.65V*
ADM705/
ADM706
POWER-FAIL
INPUT (PFI)
WATCHDOG
OUTPUT (WDO)
1.25V
RESET
POWER-FAIL
OUTPUT (PFO)
* VOLTAGE REFERENCE = 4.65V (ADM705), 4.40V (ADM706)
APPLICATIONS
00088-001
FEATURES
Figure 1. ADM705/ADM706
Microprocessor systems
Computers
Controllers
Intelligent instruments
Critical microprocessor supply monitoring
VCC
250μA
RESET
RESET
GENERATOR
VCC
4.65V*
POWER-FAIL
INPUT (PFI)
RESET
ADM707/
ADM708
POWER-FAIL
OUTPUT (PFO)
1.25V
* VOLTAGE REFERENCE = 4.65V (ADM707), 4.40V (ADM708)
00088-002
MR
Figure 2. ADM707/ADM708
GENERAL DESCRIPTION
The ADM705/ADM706/ADM707/ADM708 microprocessor
supervisory circuits are suitable for monitoring 5 V power
supplies/batteries and microprocessor activity.
The ADM705/ADM706 provide power-supply monitoring
circuitry that generate a reset output during power-up, powerdown, and brownout conditions. The reset output remains
operational with VCC as low as 1 V. Independent watchdog
monitoring circuitry is also provided. This is activated if the
watchdog input has not been toggled within 1.60 sec.
In addition, there is a 1.25 V threshold detector to warn of
power failures, to detect low battery conditions, or to monitor an
additional power supply. An active low, debounced manual reset
input (MR) is also included.
Rev. H
The ADM705 and ADM706 are identical except for the reset
threshold monitor levels, which are 4.65 V and 4.40 V, respectively.
The ADM707 and ADM708 provide a similar functionality to
the ADM705 and ADM706 and only differ in that a watchdog
timer function is not available. Instead, an active high reset
output (RESET) is available as well as the active low reset output
(RESET). The ADM707 and ADM708 are identical except for
the reset threshold monitor levels, which are 4.65 V and 4.40 V,
respectively.
All devices are available in narrow 8-lead PDIP and 8-lead SOIC
packages.
Document Feedback
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 that may result from its use. Specifications subject to change without notice. No
license is granted by implication or otherwise under any patent or patent rights of Analog Devices.
Trademarks and registered trademarks are the property of their respective owners.
One Technology Way, P.O. Box 9106, Norwood, MA 02062-9106, U.S.A.
Tel: 781.329.4700 ©2002–2016 Analog Devices, Inc. All rights reserved.
Technical Support
www.analog.com
