1.2.3 Results

When combining the circuit shown in Figure 1-1 and the code in Charge Pump Operating Code, data can be collected to show how much current the PIC microcontroller uses with different settings and voltages for the charge pump. Figure 1-2 shows the different current used by the PIC at the different settings and input voltages.
Figure 1-2. Current Used by the Charge Pump

There are four regions within the graph, separated from each other with vertical lines and labeled with the step of the code that it represents. For example, the region at the left side correlates to the Disabled setting being active. Moving to the right, this is followed by Manually Enabled, Automatically Enabled – Hardware Only, and finally the Automatically Enabled – Hardware and Analog Peripheral (DAC).

At the 5V reading (the highest line), there is a clear distinction in current used between the Disabled and Manually Enabled sections. Both Automatically Enabled sections are slightly higher than the Disabled section but are still low when compared to the Manually Enabled section. The Automatically Enabled sections are slightly higher than the Disabled level while also being distinctly lower than the Manually Enabled level; therefore, it takes some current to run the Automatically Enabled feature but not the same amount of current that is needed to run the entire charge pump.

The 4.7V reading (the second highest line) is very similar to the 5V line. The only difference is that it uses less voltage, which affects the current that is being used. The reason why the Automatically Enabled sections are slightly above the Disabled section is also the same as the 5V line.

The 4.5V reading (the second lowest line) is where the charge pump really shines. The Disabled and Manually Enabled sections are similar to the previous readings, they just shifted down to 4.5V. Around 4.6V, the charge pump gets automatically triggered. Both Automatically Enabled sections are now at a current level like the Manually Enabled section and not the Disabled section, like it was previously. This increase in current is caused by the charge pump turning on.

The 4V reading (the bottom line) is nearly identical to the 4.5V line, just with a shift down because there is less voltage available, so the current used will be less.