Datasheet

Microprocessor Supervisory Circuits
in 3-Lead SC70 and SOT-23
ADM803/ADM809/ADM810
Rev. H
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FEATURES
Specified over temperature
Low power consumption: 17 μA
Precision voltage monitor: 2.5 V, 3 V, 3.3 V, 5 V options
Reset assertion down to 1 V V
CC
140 ms minimum 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 DIAGRAMS
GND GND
V
CC
V
CC
*R
PULL-UP
ADM803/ADM809
MICROPROCESSOR
SYSTEM
V
CC
*ADM803 ONLY
RESET
INPUT
RESET
ADM803
GND
RESET
GENERATOR
240ms
RESET
RESET
(RESET)
GND
RESET
GENERATOR
240ms
ADM809/ADM810
V
CC
V
REF
V
CC
V
REF
03736-001
Figure 1.
GENERAL DESCRIPTION
The ADM803/ADM809/ADM810 supervisory circuits monitor
the power supply voltage in microprocessor systems. They
provide 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 ADM803 and
ADM809 provide an active low reset signal (
RESET
), whereas
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 (see Table 3).
The reset comparator features built-in glitch immunity, making
it immune to fast transients on V
CC
.
The ADM803/ADM809/ADM810 consume only 17 μA, making
them suitable for low power, portable equipment. The ADM803
is available in a 3-lead SC70; the ADM809/ADM810 are available
in 3-lead SOT-23 and 3-lead SC70 packages.