High Performance Automotive Sonar Intrusion – Data Sheet

AS8412

March 2001

Page 2 of 14

Key Features

• True sonar/pulse-echo operation

• Wide dynamic range

• Programmable sensitivity levels

• Self-adaptive to vehicle interiors

• Self-adaptive to temperature and environmental changes

• High sensitivity to intrusion

• Immunity to false alarms

• Detection of sabotage attempts

• Compatible with standard 40 kHz ultrasonic transducers

• No adjustments needed at factory or at field

• Few external components

• Time reference: external clock or oscillator based on crystal/ceramic resonator

• Built-in self-test

• Internal power-on-reset

• Advanced CMOS technology

• Low power consumption: 0.65 to 1.0 mA

• Operation between -40°C and +85 °C

• Available in 20-pin DIP and 20-pin SOIC package

General Description

The AS8412 is a signal processing IC designed to implement reliable, high-performance

sonar intrusion detectors. It generates short 40 kHz bursts to feed an ultrasonic trans-

ducer. The resulting sonar waves are reflected on the vehicle interior and the echoes are

received by another transducer. Inside the AS8412, the electrical signal is first submitted

to an analog conditioning circuit, then it is digitized and processed by a DSP, whose out-

put is analyzed by a discriminator based on fuzzy-logic techniques. Thus, true intrusion

conditions can be discerned from natural phenomena and other allowable disturbances.

No adjustments are necessary at factory or at the field, as the AS8412 is self-adaptive to

the physical and environmental conditions. Compact and EMI-resistant intrusion detec-

tors are made possible, due to the small number of components.

Block Diagram

PRE-

AMP

BAND-PASS

FILTER

AGC

ENVELOPE

DETECTOR

A / D

CONVERTER

D S P

DISCRIMINATOR

MODULATOR /

DRIVER

CONTROL

LOGIC

OSCILLATOR

SIGNALLING

VCAP

SAS

SENS 1

SENS 0

ALEN

LED

WARN

ALARM

SEL40K

OSCIN

OSCOUT

TX1

TX2

RX