ST STM32L4 5 Series Reference Manual page 511

RM0351
18.4.5 Slave AHB interface
The ADCs implement an AHB slave port for control/status register and data access. The
features of the AHB interface are listed below:
•
Word (32-bit) accesses
•
Single cycle response
•
Response to all read/write accesses to the registers with zero wait states.
The AHB slave interface does not support split/retry requests, and never generates AHB
errors.
18.4.6 ADC Deep-power-down mode (DEEPPWD) & ADC Voltage Regulator
(ADVREGEN)
By default, the ADC is in Deep-power-down mode where its supply is internally switched off
to reduce the leakage currents (the reset state of bit DEEPPWD is 1 in the ADC_CR
register).
To start ADC operations, it is first needed to exit Deep-power-down mode by setting bit
DEEPPWD=0.
Then, it is mandatory to enable the ADC internal voltage regulator by setting the bit
ADVREGEN=1 into ADC_CR register. The software must wait for the startup time of the
ADC voltage regulator (T
ADC. This delay must be implemented by software.
For the startup time of the ADC voltage regulator, please refer to device datasheet for
T
ADCVREG_STUP
After ADC operations are complete, the ADC can be disabled (ADEN=0). It is possible to
save power by also disabling the ADC voltage regulator. This is done by writing bit
ADVREGEN=0.
Then, to save more power by reducing the leakage currents, it is also possible to re-enter in
ADC Deep-power-down mode by setting bit DEEPPWD=1 into ADC_CR register. This is
particularly interesting before entering STOP mode.
Note: Writing DEEPPWD=1 automatically disables the ADC voltage regulator and bit ADVREGEN
is automatically cleared.
When the internal voltage regulator is disabled (ADVREGEN=0), the internal analog
calibration is kept.
In ADC Deep-power-down mode (DEEPPWD=1), the internal analog calibration is lost and
it is necessary to either relaunch a calibration or re-apply the calibration factor which was
previously saved (refer to
ADC_CALFACT)).
ADCVREG_STUP
parameter.
Section 18.4.8: Calibration (ADCAL, ADCALDIF,
DocID024597 Rev 5
Analog-to-digital converters (ADC)
) before launching a calibration or enabling the
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