FEATURES
Guaranteed RESET valid with V
190 μA quiescent current
Precision supply voltage monitor
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
APPLICATIONS
Microprocessor systems
Computers
Controllers
Intelligent instruments
Critical microprocessor supply monitoring
GENERAL DESCRIPTION
The ADM705/ADM706/ADM707/ADM708 microprocessor
supervisory circuits are suitable for monitoring 5 V power
supplies/batteries and can also monitor microprocessor activity.
The ADM705/ADM706 provide power-supply monitoring
circuitry that generate a reset output during power-up, power-
down, and brownout conditions. The reset output remains
operational with V
monitoring circuitry is also provided. This is activated if the
watchdog input has not been toggled within 1.60 seconds.
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.
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.
4.65 V (ADM705/ADM707)
4.40 V (ADM706/ADM708)
CC
as low as 1 V. Independent watchdog
CC
= 1 V
ADM705/ADM706/ADM707/ADM708
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 parts are available in narrow 8-lead PDIP and 8-lead SOIC
packages.
POWER-FAIL
POWER-FAIL
WATCHDOG
INPUT (WDI)
INPUT (PFI)
INPUT (PFI)
V
V
MR
MR
CC
CC
* VOLTAGE REFERENCE = 4.65V (ADM705), 4.40V (ADM706)
* VOLTAGE REFERENCE = 4.65V (ADM707), 4.40V (ADM708)
Low Cost Microprocessor
FUNCTIONAL BLOCK DIAGRAMS
4.65V*
1.25V
4.65V*
1.25V
WATCHDOG
TRANSITION
V
DETECTOR
V
CC
CC
250μA
250μA
Supervisory Circuits
Figure 1. ADM705/ADM706
Figure 2. ADM707/ADM708
©2008 Analog Devices, Inc. All rights reserved.
GENERATOR
GENERATOR
WATCHDOG
RESET AND
ADM705/
ADM706
WATCHDOG
TIMEBASE
RESET
RESET
ADM707/
ADM708
TIMER
WATCHDOG
OUTPUT (WDO)
RESET
POWER-FAIL
OUTPUT (PFO)
RESET
RESET
POWER-FAIL
OUTPUT (PFO)