Datasheet
TSC2101
SLAS392D− JUNE 2003 − REVISED MAY 2005
www.ti.com
39
Temperature Measurement
In some applications, such as battery charging, a measurement of ambient temperature is required. The
temperature measurement technique used in the TSC2101 relies on the characteristics of a semiconductor
junction operating at a fixed current level. The forward diode voltage (V
BE
) has a well-defined characteristic
versus temperature. The ambient temperature can be predicted in applications by knowing the 25°C value of
the V
BE
voltage and then monitoring the variation of that voltage as the temperature changes.
The TSC2101 offers two modes of temperature measurement. The first mode requires a single reading to
predict the ambient temperature. A diode, as shown in Figure 29, is used during this measurement cycle. This
voltage is typically 600 mV at +25°C with a 20-µA current through it. The absolute value of this diode voltage
can vary a few millivolts. The temperature coefficient of this voltage is typically 2 mV/°C. During the final test
of the end product, the diode voltage at a known room temperature should be stored in nonvolatile memory.
Further calibration can be done to calculate the precise temperature coefficient of the particular. This method
has a temperature resolution of approximately 0.3°C/LSB and accuracy of approximately ±2°C with
two-temperature calibration. Figure 30 and Figure 31 shows typical plots with single and two-temperature
calibration respectively.
TEMP0 TEMP1
Temperature Select
X+
MUX
A/D
Converter
Figure 29. Functional Block Diagram of Temperature Measurement Mode
−10
−8
−6
−4
−2
0
2
4
6
8
10
−40 −20 0 20 40 60 80 100
Error in Measurement −
T
A
− Free-Air Temperature − C
C
°
Figure 30. Typical Plot of Single Measurement Method After Calibrating for Offset at Room Temperature