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ASM809, ASM810
Alliance Semiconductor
2575 Augustine Drive . Santa Clara, CA 95054 . Tel: 408.855.4900 . Fax: 408.855.4999 . www.alsc.com
Notice: The information in this document is subject to change without notice
October 2003
rev 1.0
3 Pin Microcontroller Power Supply Supervisor
General Description
The ASM809/ASM810 are cost effective 3.0V, 3.3V and 5.0V
power supply supervisor circuits optimized for low-power
microprocessor (µP), microcontroller (µC) and digital systems.
They provide a reset output during power-up, power-down and
brown-out conditions. They provide excellent reliability by
eliminating external components and adjustments. The
ASM809/810 are improved drop-in replacements for the Maxim
MAX809/810 and feature 60% lower supply current.
A reset signal is issued if the power supply voltage drops below
a preset reset threshold and is asserted for at least 140ms after
the supply has risen above the reset threshold. The ASM809
has an active-low RESET
output that is guaranteed to be in the
correct logic state for V
CC
down to 1.1V. The ASM810 has an
active-high RESET output. The reset comparator is designed to
ignore fast transients on V
CC
.
Low supply current makes the ASM809/ASM810 ideal for use
in portable and battery operated equipment. The
ASM809/ASM810 are available in a compact, industry standard
3-pin SOT23 package.
Six voltage thresholds are available to support 3V to 5V
systems:
Features:
• Monitor 5V, 3.3V and 3V supplies
• 140ms min. reset pulse width
• Active-low reset valid with 1.1V supply (ASM809)
• Small 3-pin SOT-23 package
• No external components
• Specified over full temperature range - -40°C to 105°C
RESET THRESHOLD
Suffix Voltage
L4.63
M4.38
J4.00
T3.08
S2.93
R2.63
Applications
• Embedded controllers
• Portable/Battery operated systems
• Intelligent instruments
• Wireless communication systems
• PDAs and handheld equipment
• Computers
Typical Operating Circuit
V
CC
V
CC
V
CC
µP
RESET
Input
RESET
(RESET)
GND
GND
(RESET)
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