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a
ADM809/ADM810
One Technology Way, P.O. Box 9106, Norwood, MA 02062-9106, U.S.A.
Tel: 617/329-4700 World Wide Web Site: http://www.analog.com
Fax: 617/326-8703 © Analog Devices, Inc., 1997
Microprocessor
Supervisory Circuit in 3-Pin SOT-23
FUNCTIONAL BLOCK DIAGRAM
V
REF
V
CC
RESET
GENERATOR
240ms
ADM809/ADM810
RESET
(RESET)
GND
FEATURES
Superior Upgrade for MAX809/MAX810
Specified Over Temperature
Low Power Consumption (17 mA)
Precision Voltage Monitor: +3 V, +3.3 V, +5 V Options
Reset Assertion Down to 1 V V
CC
140 ms min Power-On Reset
Logic Low RESET Output (ADM809)
Logic High RESET Output (ADM810)
APPLICATIONS
Microprocessor Systems
Computers
Controllers
Intelligent Instruments
Automotive Systems
GENERAL DESCRIPTION
The ADM809/ADM810 supervisory circuits monitor the
power supply voltage in microprocessor systems. They pro-
vide a reset output during power-up, power-down and
brownout conditions. On power-up, an internal timer holds
reset asserted for 240 ms. This holds the microprocessor in a
reset state until conditions have stabilized. The RESET
output remains operational with V
CC
as low as 1 V. The
ADM809 provides an active low reset signal (RESET) while
the ADM810 provides an active high signal (RESET) output.
Six reset threshold voltage options are available suitable for
monitoring a variety of supply voltages. Refer to Table I.
The reset comparator features built-in glitch immunity,
making it immune to fast transients on V
CC
.
The ADM809/ADM810 consumes only 17 µA, making it
suitable for low power portable equipment. It is packaged in
a 3-pin SOT-23 package.
RESET
RESET
INPUT
GND GND
V
CC
V
CC
m P
SYSTEM
ADM809
V
CC
Figure 1. Typical Operating Circuit