LM73

SMBDAT

SMBCLK

ADDR

1

5

6

4

VDD = 2.7V to 5.5V

Typical bypass 0.1 PF

3

2

To hardware

shutdown

To / from processor

2-wire interface

Address (set as desired for one

of three addresses)

ALERT

20

LM73-Q1

SNIS194 – DECEMBER 2016

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Copyright © 2016, Texas Instruments Incorporated

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. Customers should

validate and test their design implementation to confirm system functionality.

8.1 Application Information

8.1.1 Thermal Path Considerations

To get the expected results when measuring temperature with an integrated circuit temperature sensor like the

LM73-Q1, it is important to understand that the sensor measures its own die temperature. For the LM73-Q1, the

best thermal path between the die and the outside world is through the LM73-Q1's pins. In the SOT23 package,

all the pins on the LM73-Q1 will have an equal effect on the die temperature. Because the pins represent a good

thermal path to the LM73-Q1 die, the LM73-Q1 will provide an accurate measurement of the temperature of the

printed circuit board on which it is mounted. There is a less efficient thermal path between the plastic package

and the LM73-Q1 die. If the ambient air temperature is significantly different from the printed circuit board

temperature, it will have a small effect on the measured temperature.

8.1.2 Output Considerations: Tight Accuracy, Resolution and Low Noise

The LM73-Q1 is well suited for applications that require tight temperature measurement accuracy. In many

applications, the low temperature error can mean better system performance and, by eliminating a system

calibration step, lower production cost.

With digital resolution as fine as 0.03125 °C/LSB, the LM73-Q1 senses and reports very small changes in its

temperature, making it ideal for applications where temperature sensitivity is important. For example, the LM73-

Q1 enables the system to quickly identify the direction of temperature change, allowing the processor to take

compensating action before the system reaches a critical temperature.

The LM73-Q1 has very low output noise, typically 0.015°C rms, which makes it ideal for applications where

stable thermal compensation is a priority. For example, in a temperature-compensated oscillator application, the

very small deviation in successive temperature readings translates to a stable frequency output from the

oscillator.

8.2 Typical Application

Figure 13. Digital Temperature Sensing

8.2.1 Design Requirements

The LM73-Q1 requires positive supply voltage of 2.7 V to 5.5 V to be applied between +VDD and GND. For best

results, bypass capacitors of 100 nF and 10 μF are recommended.