ASM1233A
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 1.0
Low Power, 3.3V, µP Reset, Active LOW, Open-Drain Output
November 2003
General Description
The ASM1233A is a voltage supervisor with low-power, 3.3V
µP Reset, with an active LOW, open-drain output. Maximum
supply current over temperature is a low 15µA.
The ASM1233A 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. The tolerance is 15% for the 3.3V, ASM1233A. 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 350ms to allow the power supply and system
microprocessor to stabilize.
The ASM1233A is designed with a open-drain output stage and
operates over the extended industrial temperature range.
Devices are available in compact SOT-223 packages.
Other low power products in this family include the ASM1810/
11/12/15/16/17, ASM1233D, and ASM1233M
Key Features
• Low Supply Current
•15µA maximum (3.6 V)
• Automatically restarts a microprocessor after power failure
• 350ms reset delay after V
CC
returns to an in-tolerance con-
dition
• Active LOW power-up reset, 5kΩ internal pull-up
• Precision temperature-compensated voltage reference and
comparator
• Eliminates external components
• Low-cost SOT-223 package
• 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
GND
Supply
Reference
Delay
350ms
Typical
Tolerance
Bias
+
-
Microprocessor
ASM1233A
V
CC
RESET
V
CC
RESET
RESET
GND
ASM1233A
5.0kΩ