TSC2117 datasheet(76/192 Pages) TI

76 / 192 page

TA − Free-Air Temperature − °C

−1.0

−0.5

0.0

0.5

1.0

1.5

2.0

2.5

3.0

3.5

G003

(Temp1

Temp2)

ln(N)

(5-10)

TSC2117

Low-Power Audio Codec With Embedded miniDSP, Stereo Class-D

Speaker Amplifier, and Smart Four-Wire Touch-Screen Controller

SLAS550A – APRIL 2009 – REVISED JUNE 2009

www.ti.com

Figure 5-44. Typical Plot of Single-Measurement Method After Calibrating

for Offset and Gain at Two Temperatures

The second mode uses a two-measurement (differential) method. This mode requires a second

conversion with a current 82 times larger. The voltage difference between the first (TEMP1) and second

(TEMP2) conversion, using 82 times the bias current, is represented by:

where

N is the current ratio = 82

k = Boltzmann’s constant (1.38054

× 10–23 electrons volts/Kelvin)

q = the electron charge (1.602189

× 10–19 C)

T = the temperature in Kelvins

The equation for the relation between differential code and temperature may vary slightly from device to

device and can be calibrated at final system test by the user. This method provides resolution of

approximately 2

°C/LSB and accuracy of approximately ±6°C after calibrating at room temperature. A plot

of typical calibration error for this method is shown in Figure 5-45.

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TSC2117 Datasheet(PDF) 76 Page - Texas Instruments