The ADC is clocked by GCLK_ADC. There is also a prescaler in the ADC to enable conversion at lower clock rates.
Refer to CTRLB for details on prescaler settings.
Figure 1. ADC Prescaler
The propagation delay of an ADC measurement
depends on the selected mode and is given by:
- Single-shot mode:
- Free-running mode:
Table 1. Delay Gain Delay Gain (in CLK_ADC Period) INTPUTCTRL.GAIN[3:0] Free-running mode Single shot mode Name Differential Mode Single-Ended Mode Differential mode Single-Ended mode 1X 0x0 0 0 0 1 2X 0x1 0 1 0.5 1.5 4X 0x2 1 1 1 2 8X 0x3 1 2 1.5 2.5 16X 0x4 2 2 2 3 Reserved 0x5 ... 0xE Reserved Reserved Reserved Reserved DIV2 0xF 0 1 0.5 1.5