1.1.3 Automatically Enabled

The charge pump can also be enabled automatically. This feature allows the application to determine when to enable the charge pump. If the charge pump is enabled while V_DD levels are above a sufficient threshold, the charge pump does not improve analog performance, but also consumes additional current. Allowing hardware to monitor V_DD and determine when to enable the charge pump prevents unnecessary current consumption.

When the CPON bits are configured as ‘10’ (as shown in Automatically Enabled - without Analog Peripheral), the charge pump hardware monitors V_DD and compares the V_DD levels to a reference voltage threshold (V_AUTO), which is fixed at 4.6V and is not configurable. When hardware detects a V_DD level lower than the threshold, the charge pump is automatically enabled. If V_DD returns to a level above the threshold, the hardware automatically disables the charge pump.

    CPCONbits.CPON = 0b10;

When the CPON bits are configured as ‘01’ (as shown in Automatically Enabled - with Analog Peripheral), the charge pump hardware waits for an analog peripheral, such as the Analog-to-Digital Converter (ADC), to be enabled before monitoring V_DD. In this case, the charge pump hardware monitors all analog peripherals, and once an analog peripheral is enabled, the hardware begins to compare V_DD to V_AUTO. When the hardware detects a V_DD level lower than the threshold, the hardware will enable the charge pump. If V_DD returns to a level above the threshold, or if the analog peripheral is disabled, the charge pump is automatically disabled.

    CPCONbits.CPON = 0b01;