Microprocessor Supervisory Circuits
in 3-Lead SC70 and SOT-23
ADM803/ADM809/ADM810
FEATURES
Specified over Temperature
Low Power Consumption (17 A)
Precision Voltage Monitor: 2.5 V, 3 V, 3.3 V, 5 V Options
Reset Assertion Down to 1 V V
CC
140 ms Min Power-On Reset
Open-Drain
RESET
Output (ADM803)
Push-Pull
RESET
Output (ADM809)
Push-Pull RESET Output (ADM810)
SC70 and SOT-23 Packages
APPLICATIONS
Microprocessor Systems
Computers
Controllers
Intelligent Instruments
Automotive Systems
FUNCTIONAL BLOCK DIAGRAM
ADM803
V
CC
V
REF
RESET
GENERATOR
240ms
RESET
GND
ADM809 / ADM810
V
CC
V
REF
RESET
GENERATOR
240ms
RESET
(RESET)
GENERAL DESCRIPTION
GND
The ADM803/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 opera-
tional with V
CC
as low as 1 V. The ADM803 and ADM809
provide an active low reset signal (RESET), while the ADM810
provides an active high signal (RESET) output. The ADM809
and ADM810 have push-pull outputs whereas the ADM803 has
an open-drain output, which requires an external pull-up resistor.
Seven 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 ADM803/ADM809/ADM810 consume only 17
碌A,
making
it suitable for low power portable equipment. The ADM803 is
available in a 3-lead SC70; the ADM809/ADM810 is available
in 3-lead SOT-23 and SC70 packages.
V
CC
V
CC
V
CC
MICROPROCESSOR
SYSTEM
RESET
INPUT
GND
*ADM803
ONLY
*R
PULL-UP
ADM803 / ADM809
RESET
GND
Figure 1. Typical Operating Circuit
REV. C
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