Figure 128. Vrefint Channel Block Diagram; Monitoring The Internal Voltage Reference - ST STM32L4x6 Reference Manual

RM0351
16.3.33

Monitoring the internal voltage reference

It is possible to monitor the internal voltage reference (V
evaluating the ADC V
The internal voltage reference is internally connected to the input channel 0 of the ADC1
(ADC1_IN0).
Refer to the electrical characteristics section of the STM32L4x6 datasheet for the sampling
time value to be applied when converting the internal voltage reference voltage.
Figure 127
Note: The VREFEN bit into ADCx_CCR register must be set to enable the conversion of internal
channels ADC1_IN0 (V
Calculating the actual V
The V
DDA
not precisely known. The embedded internal voltage reference (V
data acquired by the ADC during the manufacturing process at V
evaluate the actual V
The following formula gives the actual V
Where:
•
VREFINT_CAL is the VREFINT calibration value
• VREFINT_DATA is the actual VREFINT output value converted by ADC
Converting a supply-relative ADC measurement to an absolute voltage value
The ADC is designed to deliver a digital value corresponding to the ratio between the analog
power supply and the voltage applied on the converted channel. For most application use
cases, it is necessary to convert this ratio into a voltage independent of V
applications where V
the following formula to get this absolute value:
For applications where V
reference and V
voltage level.
REF+
shows the block diagram of the V
Figure 128. V
).
REFINT
DDA
power supply voltage applied to the microcontroller may be subject to variation or
voltage level.
DDA
V
DDA
is known and ADC converted values are right-aligned you can use
DDA
V
CHANNELx
value is not known, you must use the internal voltage
DDA
can be replaced by the expression provided in
DDA
DocID024597 Rev 3
sensing feature.
REFINT
channel block diagram
REFINT
voltage using the internal reference voltage
voltage supplying the device:
DDA
= 3.0 V x VREFINT_CAL / VREFINT_DATA
V
DDA
------------------------------------ - ×
=
FULL_SCALE
Analog-to-digital converters (ADC)
) to have a reference point for
REFINT
) and its calibration
REFINT
= 3.3 V can be used to
DDA
DDA
ADCx_DATA
Section : Calculating the
. For
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