TMP006B datasheet(22/38 Pages) TI

22 / 38 page

(

)

NORM

MEAS

Sensor

(mV)

Sensor

SampleNo

Sensor (mV)

a SampleNo b

TMP006, TMP006B

SBOS518E – MAY 2011 – REVISED APRIL 2015

www.ti.com

Typical Application (continued)

9.2.1.1 Design Requirements

For this application, the system must operate over the environment described in Table 8.

Table 8. Wide-Range Parameters

DESIGN PARAMETER

EXAMPLE VALUE

COMMENT

Number of devices in calibration set

Minimum TDIE

0°C

Minimum expected die temperature

Maximum TDIE

60°C

Maximum expected die temperature

Minimum TOBJ

0°C

Minimum expected objected temperature

Maximum TOBJ

60°C

Maximum expected object temperature

0.95

Object emissivity

Field of view

110°

Field of view subtended by object

Conversion rate

1 sample/second

Select a set of values for TDIE and TOBJ to generate the calibration set. At a minimum, include the four extreme

points of the temperature ranges desired. In practice, it is best to include a number of intermediate points as well.

This example uses the values shown in Table 9, with an X marking the values chosen for measurement.

Table 9. Wide-Range Measurement Values

TDIE

TOBJ

0°C

20°C

40°C

60°C

0°C

20°C

40°C

60°C

9.2.1.2 Detailed Design Procedure

Before attempting to calibrate the system, it is necessary to establish the stability of the system. Noise is a

measure of precision, which is the random deviation from the mean of the distribution. For a Gaussian (or

normal) distribution, the precision is typically characterized by the standard deviation (sensor noise),

σ.

9.2.1.2.1

Wide-Range Calibration

To begin calibration, select an object temperature (TOBJ) and a value for the die temperature (TDIE). With these

system temperatures stable, take a statistically significant number of samples of VSensor (results shown in register

00h).

In this example, 64 samples were taken.

To compensate for first order drift in system temperatures, it is often useful to normalize the data set. For this

purpose, for each temperature set, the sensor voltage data (given in register 00h) is normalized by first finding

the best fit line of the form shown in Equation 9:

(9)

The normalized data for each data set is then calculated as shown in Equation 10:

(10)

The normalized data, VSensor_norm, is centered on zero mean, and is first-order corrected for long-term drift. The

standard deviation for each data set is then calculated to estimate the sensor noise,

σ. Verify that the data are

limited by white noise and no other effects. For a sensor-noise-limited data set, vSENSOR σ is typically < 1 μV, and

preferably < 0.5

μV after first-order correction for drift, as described previously. If this condition is not satisfied,

then the calibration accuracy is limited by external system factors (for example, convection or conduction).

Repeat this process for each combination of TOBJ and TDIE for which the calibration is to be performed. The

normalized data are used only for evaluating the suitability of the data set for calibration, and not for the actual

calibration itself.

Submit Documentation Feedback

Product Folder Links: TMP006 TMP006B

TMP006B Datasheet(PDF) 22 Page - Texas Instruments

TMP006B Datasheet(HTML) 22 Page - Texas Instruments

Html Pages

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38

Datasheet Download

Link URL