TLH7892

April 1989

LM1812 Ultrasonic Transceiver

General Description

The LM1812 is a general purpose ultrasonic transceiver de-

signed for use in a variety of ranging sensing and commu-

nications applications The chip contains a pulse-modulated

class C transmitter a high gain receiver a pulse modulation

detector and noise rejection circuitry

A single LC network defines the operating frequency for

both the transmitter and receiver The class C transmitter

output drives up to 1A (12W) peak at frequencies up to

325 kHz The externally programmed receiver gain provides

a detection sensitivity of 200 mVp-p Detection circuitry in-

cluded on-chip is capable of rejecting impulse noise with

external programming The detector output sinks up to 1A

Applications include sonar systems non-contact ranging

and acoustical data links in both liquid and gas ambients

Features

Y

One or two-transducer operation

Y

Transducers interchangeable without realignment

Y

No external transistors

Y

Impulse noise rejection

Y

No heat sinking

Y

Protection circuitry included

Y

Detector output drives 1A peak load

Y

Ranges in excess of 100 feet in water 20 feet in air

Y

12W peak transmit power

Applications

Y

Liquid level measurement

Y

Sonar

Y

Surface profiling

Y

Data links

Y

Hydroacoustic communications

Y

Non-contact sensing

Y

Industrial process control

Typical Application

TLH7892 – 1

Order Number LM1812N

See NS Package Number N18A

Note Echo returns are displayed by a neon lamp on a motor driven disc Connections to the neon are made through brushes and slip rings Rotating with

and counterbalancing the neon lamp is a permanent magnet whose field induces a pulse in a stationary coil (L8) as it passes by This pulse keys the

LM1812’s transmitter

Available from Toko America 1250 Feehanville Drive Mount Prospect Illinois 60056 Tel (312) 297-0070

Available from Massa Products Corporation 280 Lincoln Street Hingham Massachusetts 02043 Tel (617) 749-4800

FIGURE 1 200 kHz Depth Sounder 5 Feet to 100 Feet

C1995 National Semiconductor Corporation

RRD-B30M115Printed in U S A