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a
ADM809-5S/L
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 © Analog Devices, Inc., 2000
Microprocessor
Supervisory Circuit
FUNCTIONAL BLOCK DIAGRAM
V
REF
V
CC
RESET
GENERATOR
55ms
ADM809-5S/L
RESET
GND
FEATURES
Specified Over Temperature
Low Power Consumption (17 H9262A)
Precision Voltage Monitor: 3 V, 5 V Options
Reset Assertion Down to 1 V V
CC
30 ms min Power-On Reset
Logic Low RESET Output
APPLICATIONS
Microprocessor Systems
Computers
Controllers
Intelligent Instruments
Automotive Systems
GENERAL DESCRIPTION
The ADM809-5S/L supervisory circuits monitor the power
supply voltage in microprocessor systems. It provides a reset
output during power-up, power-down and brownout conditions.
On power-up, an internal timer holds reset asserted for 55 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 ADM809-5S/L provides an active low
reset signal (RESET).
The reset comparator features built-in glitch immunity,
making it immune to fast transients on V
CC
.
The ADM809-5S/L consumes only 17 µA, making it suitable
for low power portable equipment.
RESET
RESET
INPUT
GND GND
V
CC
V
CC
H9262P
SYSTEM
ADM809-5S/L
V
CC
Figure 1. Typical Operating Circuit