8 Application and Implementation

Note

Information in the following applications sections is not part of the TI component specification,

and TI does not warrant its accuracy or completeness. TI’s customers are responsible for

determining suitability of components for their purposes, as well as validating and testing their design

implementation to confirm system functionality.

8.1 Application Information

The LM50 has a wide supply range and a 10mV/°C output slope with a 500mV DC offset. Therefore, the device

can be easily placed in many temperature-sensing applications where a single supply is required for positive and

negative temperatures.

8.2 Typical Application

8.2.1 Full-Range Centigrade Temperature Sensor

LM50

LM50-Q1

+VS

(4.5 V to 10 V)

Output

Copyright © 2016, Texas Instruments Incorporated

Figure 8-1. Full-Range Centigrade Temperature Sensor Diagram (–40°C to 125°C)

8.2.1.1 Design Requirements

For this design example, use the parameters listed in Table 8-1 as the input parameters.

Table 8-1. Design Parameters

PARAMETER

VALUE

Power supply voltage

4.5V to 10V

Output impedance

4kΩ (maximum)

Accuracy at 25°C

±2°C/±3°C (maximum)

Accuracy over –40°C to 125°C

±3°C/±4°C (maximum)

Temperature slope

10mV/°C

8.2.1.2 Detailed Design Procedure

The LM50 is a simple temperature sensor that provides an analog output. Therefore design requirements related

to layout are more important than other requirements. See Layout for more information.

8.2.1.2.1 Capacitive Loads

The LM50 handles capacitive loading very well. Without any special precautions, the LM50 can drive any

capacitive load. The device has a nominal 2kΩ output impedance (shown in Functional Block Diagram).

The temperature coefficient of the output resistors is approximately 1300ppm/°C. Taking into account this

temperature coefficient and the initial tolerance of the resistors the output impedance of the device does not

exceed 4kΩ. In an extremely noisy environment adding filtering can be necessary to minimize noise pickup. TI

recommends adding a 0.1µF capacitor between +VS and GND to bypass the power supply voltage, as shown in

Figure 8-3. Adding a capacitor from VO to ground can be necessary. A 1µF output capacitor with the 4kΩ output

LM50

SNIS118H – JULY 1999 – REVISED MAY 2025

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