Microprocessor Supervisory Circuits
in 3-Lead SC70 and SOT-23
ADM803/ADM809/ADM810
FEATURES
FUNCTIONAL BLOCK DIAGRAM
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 VCC
140 ms Min Power-On Reset
ADM803
V
CC
RESET
GENERATOR
240ms
RESET
V
Open-Drain RESET Output (ADM803)
Push-Pull RESET Output (ADM809)
Push-Pull RESET Output (ADM810)
SC70 and SOT-23 Packages
REF
GND
APPLICATIONS
Microprocessor Systems
Computers
ADM809/ADM810
Controllers
Intelligent Instruments
Automotive Systems
V
CC
RESET
GENERATOR
240ms
RESET
(RESET)
V
REF
GND
GENERAL DESCRIPTION
The ADM803/ADM809/ADM810 supervisory circuits monitor
the power supply voltage in microprocessor systems. They pro
vide a reset output during powerup, powerdown, and brownout
conditions. On powerup, 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 VCC 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 pushpull outputs, whereas the ADM803 has
an opendrain output, which requires an external pullup resistor.
V
CC
V
V
CC
CC
*R
PULL-UP
MICROPROCESSOR
SYSTEM
ADM803/ADM809
RESET
INPUT
RESET
GND
GND
Seven reset threshold voltage options are available, suitable for
monitoring a variety of supply voltages. Refer to Table I.
*ADM803 ONLY
Figure 1. Typical Operating Circuit
The reset comparator features builtin glitch immunity, making
it immune to fast transients on VCC
.
The ADM803/ADM809/ADM810 consume only 17 mA,
making them suitable for low power, portable equipment.
The ADM803 is available in a 3lead SC70; the ADM809/
ADM810 is available in 3lead SOT23 and SC70 packages.
REV. F
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