The ADC module includes a dedicated charge pump. The purpose of the charge pump is to ensure that the ADC internal logic remains at a constant voltage level, which helps ensure consistent ADC operation, especially at lower device operating voltages.
The ADC charge pump is enabled/disabled via the Charge Pump On (CPON) bit of the ADC
Charge Pump Control (ADCP) register. Once the charge pump is enabled (CPON =
1), the pump must undergo a stabilization period, which may take up
to 35 us. Once the pump’s output has stabilized and is ready for use, the Charge Pump
Ready Status (CPRDY) bit is set.
It should be noted that the charge pump consumes additional current when enabled. When device VDD is above 3.5V, internal voltage levels are sufficient for consistent ADC operation; therefore, the use of the charge pump will not be effective in improving ADC performance, but will continue to draw current.