TI Device

LM131

+

0.01µF

3

5

4

2

1

6

7

1µF

12k

5k

0.01µF

100k

GND

6V

6.8k

1k

4N28

8

fOUT

100k

47

FULL

SCALE

ADJ

Copyright © 2016, Texas Instruments Incorporated

–40°C to 125°C; 100Hz to 1750Hz

Figure 8-12. LM50 and LM50HV With Voltage-To-Frequency Converter and Isolated Output

8.4 Power Supply Recommendations

In an extremely noisy environment, adding some filtering to minimize noise pickup can be necessary. TI

recommends that a 0.1µF capacitor be added from +VS to GND to bypass the power supply voltage, as shown in

Figure 8-3.

8.5 Layout

8.5.1 Layout Guidelines

The LM50 and LM50HV can be applied easily in the same way as other integrated-circuit temperature sensors.

The device can be glued or cemented to a surface and the temperature is within about 0.2°C (for power supply

up to 10V) of the surface temperature.

This presumes that the ambient air temperature is approximately the same as the surface temperature; if the air

temperature are much higher or lower than the surface temperature, the actual temperature of the LM50 and

LM50HV dies are at an intermediate temperature between the surface temperature and the air temperature.

To provide good thermal conductivity, the backside of the LM50 and LM50HV dies are directly attached to the

GND pin. The lands and traces to the device is part of the printed-circuit board, which is the object whose

temperature is being measured. These printed-circuit board lands and traces do not cause the LM50 and

LM50HV temperature to deviate from the desired temperature.

Alternatively, the LM50 and LM50HV can be mounted inside a sealed-end metal tube, and can then be dipped

into a bath or screwed into a threaded hole in a tank. As with any device, the LM50 and LM50HV and

accompanying wiring and circuits must be kept insulated and dry, to avoid leakage and corrosion. This is

especially true if the circuit can operate at cold temperatures where condensation can occur. Printed-circuit

coatings and varnishes such as HUMISEAL® and epoxy paints or dips are often used to verify that moisture

cannot corrode the device or the connections.

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LM50, LM50HV

SNIS118I – JULY 1999 – REVISED OCTOBER 2025

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Product Folder Links: LM50 LM50HV