TLH8709

February 1995

LM1042 Fluid Level Detector

General Description

The LM1042 uses the thermal-resistive probe technique to

measure the level of non-flammable fluids An output is pro-

vided proportional to fluid level and single shot or repeating

measurements may be made All supervisory requirements

to control the thermal-resistive probe including short and

open circuit probe detection are incorporated within the de-

vice A second linear input for alternative sensor signals

may also be selected

Features

Y

Selectable thermal-resistance or linear probe inputs

Y

Control circuitry for thermal-resistive probe

Y

Single-shot or repeating measurements

Y

Switch on reset and delay to avoid transients

Y

Output amplifier with 10 mA source and sink capability

Y

Short or open probe detection

Y

a

50V transient protection on supply and control input

Y

75V to 18V supply range

Y

Internally regulated supply

Y

b

Block Diagram

TLH8709 – 1

C1995 National Semiconductor Corporation

RRD-B30M115Printed in U S A