MSP430 datasheet(35/88 Pages) TI

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7.3.2.6 Temperature Sensor

Channel 3 of the CCS is used to measure the die temperature of the device. The ADC measures an internal

temperature sensor that measures a voltage complementary to the absolute temperature (CTAT). This CTAT

voltage has a negative temperature coefficient. The ADC converts this voltage at a data rate of 2560 Hz. When

the ADC conversion is completed, the data are found in the ADC_TEMP.DATA bits (address 26h).

The relationship between the ambient temperature and the ADC code is shown in Equation 8:

ADCCode=2681−11×TA°C

(8)

7.3.2.7 Self-Diagnostic Multiplexer

In addition to the ADC offset, the two external monitoring inputs, and the temperature sensor, the ADC of the

AFEx8101 has five other internal inputs to monitor the reference voltage, the power supplies, a static voltage,

and the DAC output. These five voltages measurements are part of the self-diagnostic multiplexer (SD0 to SD4)

measurements of the ADC, and are reported in the ADC_SD_MUX register at 27h; see also Section 7.6.

Channel 4 (SD0) measures the reference voltage of the device. The ADC measures the reference voltage

through a resistor divider (divide by two). Be aware that all ADC measurements are a function of the reference;

using SD0 to measure the reference is not revealing as a diagnostic measurement. The data rate for this

conversion is 2560 Hz and the range of the ADC is set to VREF.

Channel 5 (SD1) measures the PVDD power supply of the device. The ADC measures the PVDD voltage

through a resistor divider (divide by six). The data rate for this conversion is 2560 Hz and the range of the ADC

is set to VREF.

Channel 6 (SD2) measures the VDD power supply of the device. When channel 6 is selected, the ADC

measures the VDD voltage through a resistor divider (divide by 2). The data rate for this conversion is 2560 Hz

and the range of the ADC is set to VREF.

Channel 7 (SD3) is a ZTAT (zero temperature coefficient) voltage. This internal voltage is nominally 0.6 V with a

low temperature drift and does not depend on the reference voltage. An ADC measurement of ZTAT voltage can

be useful to determine the state of the reference voltage. The data rate for this conversion is 2560 Hz and the

range of the ADC is set to VREF.

Channel 8 (SD4) measures the VOUT of the DAC. The ADC measures the VOUT voltage through a resistor

divider (divide by two). The data rate for this conversion is 2560 Hz.

The input range for the DAC voltage monitoring input is scaled from either 0-V to 2.5-V or 0-V to 1.25-V,

depending on PVDD voltage. As soon as the PVDD voltage exceeds 2.7 V, the input range for the DAC voltage

monitoring automatically switches to the 0-V to 2.5-V range. The DAC voltage conversion values are stored in

straight-binary format in the ADC registers. The ADC resolution for these channels is computed by Equation 7.

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AFE78101, AFE88101

SLASF21 – DECEMBER 2022

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MSP430 датащи(PDF) 35 Page - Texas Instruments