NSC LM1830N Datasheet
LM1830 Fluid Detector
LM1830 Fluid Detector
February 1995
General Description
The LM1830 is a monolithic bipolar integrated circuit designed for use in fluid detection systems. The circuit is ideal
for detecting the presence, absence, or level of water, or
other polar liquids. An AC signal is passed through two
probes within the fluid. A detector determines the presence
or absence of the fluid by comparing the resistance of the
fluid between the probes with the resistance internal to the
integrated circuit. An AC signal is used to overcome plating
problems incurred by using a DC source. A pin is available
for connecting an external resistance in cases where the
fluid impedance is of a different magnitude than that of the
internal resistor. When the probe resistance increases
above the preset value, the oscillator signal is coupled to
the base of the open-collector output transistor. In a typical
application, the output could be used to drive a LED, loud
speaker or a low current relay.
Logic and Connection Diagram
Dual-In-Line Package
Features
Y
Low external parts count
Y
Wide supply operating range
Y
One side of probe input can be grounded
Y
AC coupling to probe to prevent plating
Y
Internally regulated supply
Y
AC or DC output
Applications
Y
Beverage dispensers
Y
Water softeners
Y
Irrigation
Y
Sump pumps
Y
Aquaria
Y
Radiators
Y
Washing machines
Y
Reservoirs
Y
Boilers
Order Number LM1830N
TL/H/5700– 1
See NS Package Number N14A
C
1995 National Semiconductor Corporation RRD-B30M115/Printed in U. S. A.
TL/H/5700
Absolute Maximum Ratings
If Military/Aerospace specified devices are required,
please contact the National Semiconductor Sales
Office/Distributors for availability and specifications.
Supply Voltage 28V
Power Dissipation (Note 1) 1400 mW
Electrical Characteristics (V
e
16V, T
e
A
a
Parameter Conditions Min Typ Max Units
Supply Current 5.5 10 mA
Oscillator Output Voltage
Low 1.1 V
High 4.2 V
Internal Reference Resistor 8 13 25 kX
Detector Threshold Voltage 680 mV
Detector Threshold Resistance 5 10 15 kX
Output Saturation Voltage I
Output Leakage V
Oscillator Frequency C1
Note 1: The maximum junction temperature rating of the LM1830N is 150§C. For operation at elevated temperatures, devices in the dual-in-line plastic package
must be derated based on a thermal resistance of 89
e
10 mA 0.5 2.0 V
O
e
16V 10 mA
PIN 12
e
0.00 1mF 4 7 12 kHz
C/W.
§
Output Sink Current 20 mA
Operating Temperature Range
Storage Temperature Range
b
Lead Temp. (Soldering, 10 seconds) 260§C
25§C unless otherwise specified)
b
40§Ctoa85§C
40§Ctoa150§C
Schematic Diagram
TL/H/5700– 2
2
Typical Performance Characteristics
Normalized Oscillator Frequency
vs Supply Voltage
Threshold Resistance vs Supply
Voltage
Power Supply Current vs
Supply Voltage
Reference Resistor vs Ambient
Temperature
Oscillator V
vs Ambient Temperature
OH
and V
OL
Detector Threshold Voltage
vs Temperature
Output Saturation Voltage vs
Output Current
Equivalent Resistance vs
Concentration of Several
Solutions
Probe Threshold Resistance
vs Temperature
Oscillator Frequency vs
Ambient Temperature
TL/H/5700– 3
3
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