ASM1811
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
rev 1.4
Low Power 5V µP Reset Active LOW, Open - Drain Output
February 2005
General Description
The ASM1811 is a voltage supervisory device with a low-power,
5V µP Reset, active LOW, open-drain output. Maximum supply
current over temperature is a low 20µA.
The ASM1811 generates an active LOW reset signal whenever
the monitored supply is out of tolerance. A precision reference
and comparator circuit monitor power supply (V
CC
) level.
Tolerance level options are 5%, 10% and 15%. When an out-of-
tolerance condition is detected, an internal power-fail signal is
generated which forces an active LOW reset signal. After V
CC
returns to an in-tolerance condition, the reset signal remains
active for 150ms to allow the power supply and system
microprocessor to stabilize.
The ASM1811 is designed with a open-drain output stage and
operates over the extended industrial temperature range.
Devices are available in low cost TO-92 and compact surface
mount SOT-23 packages.
Other low power products in this family include the ASM1810/
12/15/16/17, ASM1233D and ASM1233M.
Key Features
• Low Supply Current
•20 µA maximum (5.5 V)
• Automatically restarts a microprocessor after power failure
• 150ms reset delay after V
CC
returns to an in-tolerance con-
dition
• Active LOW power-up reset
• Precision temperature-compensated voltage reference and
comparator
• Eliminates external components
• Low cost TO-92 and compact surface mount SOT-23 pack-
ages
• Operating temperature -40°C to +85°C
Applications
• Set-top boxes
• Cellular phones
•PDAs
• Energy management systems
• Embedded control systems
• Printers
• Single board computers
Typical Operating Circuit
Block Diagram
Microprocessor
V
CC
RESET
RESET
GND
ASM1811
V
CC
Supply
Reference
Delay
150ms
Typical
Tolerance
Bias
+
-
2
ASM1811
GND
RESET
1
3
5.5KΩ