500
550
600
650
700
750
800
850
900
950
–40
–20
0
20
40
60
80
T
ypical
T
emperature Sensor V
oltage (mV)
Ambient Temperature (°C)
ADC12_B Operation
883
SLAU367P – October 2012 – Revised April 2020
Copyright © 2012–2020, Texas Instruments Incorporated
ADC12_B
These interrupts are generated independently of the conversion mode selected by the user. The update of
the window comparator interrupt flags happen after the ADC12IFGx.
The lower and higher threshold in the ADC12LO and ADC12HI registers have to be given in the correct
data format. If the binary unsigned data format is selected by ADC12DF = 0, then the thresholds in the
registers ADC12LO and ADC12HI must be written as binary unsigned values. If the signed binary (2s
complement) data format is selected by ADC12DF = 1, then the thresholds in the registers ADC12LO and
ADC12HI must be written as signed binary (2s complement). Altering the ADC12DF register or the
ADC12RES register resets the threshold registers.
The interrupt flags are reset by the user software. The ADC12_B sets the interrupt flags each time a new
conversion result is available in the ADC12MEMx register if applicable. Interrupt flags are not cleared by
hardware. The user software resets the window comparator interrupt flags per the application needs.
34.2.11 Using the Integrated Temperature Sensor
To use the on-chip temperature sensor, the user must enable the temperature sensor input channel by
setting the ADC12TCMAP bit equal to 1 in the ADC12CTL3 register. The user must then select the analog
input channel ADC12INCHx = 0x1E for the temperature sensor. Any other configuration is done as if an
external channel were selected, including reference selection, conversion-memory selection, and so on.
The temperature sensor is in the REF module.
A typical temperature sensor transfer function is shown in
. The transfer function shown is
only an example. Calibration is required to determine the corresponding voltages for a specific device.
When using the temperature sensor, the sample period must be greater than 30 µs. The temperature
sensor offset error can be large and may need to be calibrated for most applications. Temperature
calibration values are available for use in the TLV descriptors (see the device-specific data sheet for
locations). Some MSP430 devices include calibration data that can be used to compute temperature more
accurately. For more information, refer to
.
Selecting the temperature sensor automatically turns on the on-chip reference generator as a voltage
source for the temperature sensor. However, it does not enable the VREF+ output or affect the reference
selections for the conversion. The reference choices for converting the temperature sensor are the same
as with any other channel.
Figure 34-12. Typical Temperature Sensor Transfer Function