LM50/

LM50-Q1

LM131

+

0.01 µF

3

5

4

2

1

6

7

1 µF

12 K

5 k

0.01 µF

100 K

GND

6 V

6.8 K

1 K

4N28

8

fOUT

100 K

47

FULL

SCALE

ADJ

Copyright © 2016, Texas Instruments Incorporated

–40°C to 125°C; 100Hz to 1750Hz

Figure 8-7. LM50 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 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 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 die is at

an intermediate temperature between the surface temperature and the air temperature.

To provide good thermal conductivity, the backside of the LM50 die is 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 temperature to deviate from the

desired temperature.

Alternatively, the LM50 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 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

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LM50

SNIS118H – JULY 1999 – REVISED MAY 2025

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