a
Microprocessor
Supervisory Circuits
ADM698/ADM699
FEATURES
Superior Upgrade for MAX698/MAX699
Guaranteed RESET Assertion with VCC = 1 V
Low 0.6 mA Supply Current
Precision 4.65 V Voltage Monitor
Power OK/Reset Time Delay
Watchdog Timer
Minimum Component Count
Performance Specified over Temperature
APPLICATIONS
Microprocessor Systems
Computers
Controllers
Intelligent Instruments
Automotive Systems
Critical P Power Monitoring
FUNCTIONAL BLOCK DIAGRAM
ADM698/
ADM699
RESET*
VCC
RESET
GENERATOR
RESET
4.65V
WATCHDOG
INPUT
WDI*
WATCHDOG
TRANSITION DETECTOR
(1 sec)
WATCHDOG
OUTPUT WDO*
*WDI (ADM699 ONLY)
RESET (SOIC ONLY)
WDO (ADM699 SOIC ONLY)
TYPICAL APPLICATION CIRCUIT
GENERAL DESCRIPTION
The ADM698/ADM699 supervisory circuits provide power
supply monitoring and watchdog timing for microprocessor
systems.
The ADM698 monitors the 5 V VCC power supply and generates a RESET pulse during power up, power down and during
low voltage “Brown Out” conditions. The RESET output is
guaranteed to be functional (logic low) with VCC as low as 1 V.
The ADM699 features an identical monitoring circuit as in the
ADM698 plus an additional watchdog timer input to monitor
microprocessor activity. The RESET output is forced low if the
watchdog input is not toggled within the 1 second watchdog
timeout period.
+5V
VCC
µP POWER
RESET
µP RESET
ADM698/
ADM699
µP SYSTEM
WDI*
I/O LINE
GND
*ADM699 ONLY
Both parts are available in 8-pin plastic DIP and 16-lead SOIC
packages. The 16-lead SOIC contains additional outputs
RESET (without inversion) and Watchdog Output WDO
(ADM699 only).
REV. 0
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: 617/329-4700
Fax: 617/326-8703
