ASM811, ASM812

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

4 Pin µP Voltage Supervisor with Manual Reset

General Description

The ASM811/ASM812 are cost effective low power supervisors

designed to monitor voltage levels of 3.0V, 3.3V and 5.0V

power

supplies

in

low-power

microprocessor

(µP),

microcontroller (µC) and digital systems. They provide excellent

reliability by eliminating external components and adjustments.

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 ASM811

has an active-low output RESET that is guaranteed to be in the

high RESET output. The reset comparator is designed to ignore

the user to manually reset the systems to bring them out of

locked state.

Low power consumption makes the ASM811/ASM812 ideal for

use in portable and battery operated equipment. The ASM811/

ASM812 are available in a compact 4-pin SOT-143 package

and thus use minimal board space.

Six voltage thresholds are available to support 3V to 5V

systems:

Features

•

New 4.0V threshold option

•

9µA supply current

•

Monitor 5V, 3.3V and 3V supplies

•

Manual reset input

•

140ms min. reset pulse width

•

Guaranteed over temperature

•

Active-low reset valid with 1.1V supply (ASM811)

•

Small 4-pin SOT-143 package

•

No external components

•

Power-supply transient-immune design

RESET THRESHOLD

Suffix

Voltage

L4.63

M4.38

J4.00

T3.08

S2.93

R2.63

Applications

•

Computers and Controllers

•

Embedded controllers

•

Portable/Battery operated systems

•

Intelligent instruments

•

Wireless communication systems

•

PDAs and handheld equipment

•

Automotive systems

•

Safety Systems

Typical Operating Circuit

µP

RESET

Input

RESET

(RESET)

GND

GND

(RESET)

MR