Temperature Sensor
PXR40 Microcontroller Reference Manual, Rev. 1
Freescale Semiconductor
34-3
34.3
Temperature formula
The temperature formula is shown in
.
Figure 34-2. Temperature formula
The following sections detail the values required and where to get them.
34.3.1
T
LOW
and T
HIGH
T
LOW
is the factory low calibration temperature; T
HIGH
is the hot factory calibration temperature. These
values are stored in shadow flash memory during factory calibration. See
Calculation Constants Register 0
, for details.
34.3.2
T
TSENS_CODE
(T
LOW
) and T
TSENS_CODE
(T
HIGH
)
T
TSENS_CODE
(T
LOW
) is the sampled output voltage of the temperature sensor during low temperature
factory calibration. T
TSENS_CODE
(T
HIGH
) is the sampled output voltage of the temperature sensor during
hot temperature factory calibration. These values are stored in shadow flash memory during factory
calibration. See
Section 34.3.6.1, Temperature Calculation Constants Register 0
, for details.
=
V
BG_CODE
(T
LOW
)
T
TSENS_CODE
(T) x
– T
TSENS_CODE
(T
LOW
)
T
TSENS_CODE
(T
HIGH
) – T
TSENS_CODE
(T
LOW
)
T = T
LOW
+
x (T
HIGH
– T
LOW
)
T
TSENS_CODE
(T) =
V
TSENS
(T)
V
ref
x 2
14
T
TSENS_CODE
(T
LOW
) =
V
TSENS
(T
LOW
)
V
ref0
x 2
14
T
TSENS_CODE
(T
HIGH
) =
V
TSENS
(T
HIGH
)
V
ref0
x 2
14
V
BG_CODE
(T) =
V
BG
(T)
V
ref
x 2
14
V
BG_CODE
(T
LOW
) =
V
BG
(T
LOW
)
V
ref0
x 2
14
V
BG_CODE
(T)
where:
Notes:
• V
TSENS
(T) is the temperature sensor output sampled by the ADC
• V
BG
(T) is the bandgap voltage sampled by the ADC
• V
ref
is the ADC reference voltage
• V
ref0
is the ADC reference voltage during factory calibration
• T
LOW
is the low temperature factory calibration temperature (stored in device flash)
• T
HIGH
is the hot factory calibration temperature (stored in device flash)
(Stored in device flash during factory calibration)
(Stored in device flash during factory calibration)
(Stored in device flash during factory calibration)
Summary of Contents for PXR4030
Page 1: ...PXR40 Microcontroller Reference Manual Devices Supported PXR4030 PXR4040 PXR40RM Rev 1 06 2011...
Page 30: ...PXR40 Microcontroller Reference Manual Rev 1 Freescale Semiconductor xxx...
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