Datasheet

Functional overview STM32L431xx
34/200 DocID028800 Rev 1
3.15.2 Internal voltage reference (V
REFINT
)
The internal voltage reference (VREFINT) provides a stable (bandgap) voltage output for
the ADC and Comparators. VREFINT is internally connected to the ADC1_IN0 input
channel. The precise voltage of VREFINT is individually measured for each part by ST
during production test and stored in the system memory area. It is accessible in read-only
mode.
3.15.3 V
BAT
battery voltage monitoring
This embedded hardware feature allows the application to measure the V
BAT
battery voltage
using the internal ADC channel ADC1_IN18. As the V
BAT
voltage may be higher than
VDDA, and thus outside the ADC input range, the VBAT pin is internally connected to a
bridge divider by 3. As a consequence, the converted digital value is one third the V
BAT
voltage.
3.16 Digital to analog converter (DAC)
Two 12-bit buffered DAC channels can be used to convert digital signals into analog voltage
signal outputs. The chosen design structure is composed of integrated resistor strings and
an amplifier in inverting configuration.
This digital interface supports the following features:
Up to two DAC output channels
8-bit or 12-bit output mode
Buffer offset calibration (factory and user trimming)
Left or right data alignment in 12-bit mode
Synchronized update capability
Noise-wave generation
Triangular-wave generation
Table 7. Temperature sensor calibration values
Calibration value name Description Memory address
TS_CAL1
TS ADC raw data acquired at a
temperature of 30 °C (± 5 °C),
V
DDA
= V
REF+
= 3.0 V (± 10 mV)
0x1FFF 75A8 - 0x1FFF 75A9
TS_CAL2
TS ADC raw data acquired at a
temperature of 130 °C (± 5 °C),
V
DDA
= V
REF+
= 3.0 V (± 10 mV)
0x1FFF 75CA - 0x1FFF 75CB
Table 8. Internal voltage reference calibration values
Calibration value name Description Memory address
VREFINT
Raw data acquired at a
temperature of 30 °C (± 5 °C),
V
DDA
= V
REF+
= 3.0 V (± 10 mV)
0x1FFF 75AA - 0x1FFF 75AB
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