LM3S5956 Datasheet, PDF (559/1261 Pages) Texas Instruments – Stellaris® LM3S5951 Microcontroller

Stellaris^® LM3S5951 Microcontroller
12.3.6
Internal Temperature Sensor
The temperature sensor serves two primary purposes: 1) to notify the system that internal temperature
is too high or low for reliable operation and 2) to provide temperature measurements for calibration
of the Hibernate module RTC trim value.
The temperature sensor does not have a separate enable, because it also contains the bandgap
reference and must always be enabled. The reference is supplied to other analog modules; not just
the ADC. In addition, the temperature sensor has a second power-down input in the 3.3 V domain
which provides control by the Hibernation module.
The internal temperature sensor provides an analog temperature reading as well as a reference
voltage. This reference voltage, SENSO, is given by the following equation:
SENSO = 2.7 - ((T + 55) / 75)
This relation is shown in Figure 12-13 on page 559.
Figure 12-13. Internal Temperature Sensor Characteristic
Sensor = 2.7 V – ^(T+55)
75
Sensor
2.7 V
1.633 V
0.3 V
-55° C
25° C
125° C Temp
12.3.7
The temperature sensor reading can be sampled in a sample sequence by setting the TSn bit in
the ADCSSCTLn register. The temperature reading from the temperature sensor can also be given
as a function of the ADC value. The following formula calculates temperature (in ℃) based on the
ADC reading:
Temperature = 147.5 - ((225 × ADC) / 1023)
Digital Comparator Unit
An ADC is commonly used to sample an external signal and to monitor its value to ensure that it
remains in a given range. To automate this monitoring procedure and reduce the amount of processor
January 20, 2012
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