PXS20RM Datasheet, PDF (1355/1368 Pages) Freescale Semiconductor, Inc – PXS20 Microcontroller

Chapter 50
Temperature Sensor (TSENS)
Temperature Sensor (TSENS)
50.1 Introduction
The TSENS module provides an analog voltage that is proportional to the internal temperature of the
PXS20. This voltage can be sampled by the ADC and converted to an actual temperature by using
factory-programmed calibration constants.
Figure 50-1 shows a block diagram of the TSENS module. The module operates on the principles of a
basic silicon bandgap sensor that measures the difference in base-emitter voltages of multiple transistors,
which can be related to the absolute temperature of the device.
ADC CTR1[TSENSOR_SEL]
Bias
Level shifter
+
logic
Analog
delay
Mode
select
Sensing
diodes
V_BE0
V_BE1
Instr. amp
2-to-1
mux 1
Figure 50-1. TSENS block diagram
2-to-1
mux 2
V_TSENS
50.2 Features
The TSENS has the following features:
• Temperature monitoring range: –40–150 C
• Sensitivity: Approximately 5.14 mV/C
50.3 Signals
The TSENS does not use any input signals external to the device.
The TSENS outputs one analog signal, V_TSENS. Depending on the TSENS mode of operation, V_TSENS is
proportional or inversely proportional to the device temperature. See Chapter 9, Analog-to-Digital
Converter (ADC), for information on which ADC channels are connected to V_TSENS.
50.4 Modes of operation
The TSENS has two modes of operation:
• Proportional to absolute temperature (PTAT) — V_TSENS increases linearly with increasing
temperature
Freescale Semiconductor
PXS20 Microcontroller Reference Manual, Rev. 1
50-1