
DocID024597 Rev 5
511/1830
RM0351
Analog-to-digital converters (ADC)
614
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
ADCVREG_STUP
) before launching a calibration or enabling the
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
parameter.
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
Section 18.4.8: Calibration (ADCAL, ADCALDIF,
).