Datasheet

875
SAM9G15 [DATASHEET]
11052D–ATARM–31-Oct-12
41.5.6 Conversion Performances
For performance and electrical characteristics of the ADC, see the product DC Characteristics section.
41.6 Functional Description
41.6.1 Analog-to-digital Conversion
The ADC uses the ADC Clock to perform conversions. Converting a single analog value to a 10-bit digital data requires
Tracking Clock cycles as defined in the field TRACKTIM of the “ADC Mode Register” on page 895 and Transfer Clock
cycles as defined in the field TRANSFER of the same register. The ADC Clock frequency is selected in the PRESCAL
field of the Mode Register (ADC_MR). The tracking phase starts during the conversion of the previous channel. If the
tracking time is longer than the conversion time, the tracking phase is extended to the end of the previous conversion.
The ADC clock range is between MCK/2, if PRESCAL is 0, and MCK/512, if PRESCAL is set to 255 (0xFF). PRESCAL
must be programmed in order to provide an ADC clock frequency according to the parameters given in the product
Electrical Characteristics section.
Figure 41-2. Sequence of ADC conversions
ADCClock
LCDR
ADC_ON
ADC_SEL
DRDY
ADC_Start
CH0 CH1
CH0
CH2
CH1
Start Up Time
(and tracking of CH0)
Conversion of CH0 Conversion of CH1Tr acking of CH1
Tracking of CH2
ADC_eoc
Trigger event
(Hard or Soft)
Analog cell IOs