Comparators are used to interface analog circuits to a digital circuit by comparing two analog voltages and providing a digital indication of their relative magnitudes. Comparators are very useful mixed signal building blocks because they provide analog functionality independent of program execution. Inside many PIC® MCU devices is a comparator module (some devices have more than one) so you can control it through software. The internal comparator module includes the following features:
- Independent comparator control
- Programmable input selection
- Comparator output is available internally/externally
- Programmable output polarity
- Wake-up from Sleep
- Programmable Speed/Power optimization
- PWM shutdown
- Programmable and fixed voltage reference
A single comparator is shown in Figure above along with the relationship between the analog input levels and the digital output. When the analog voltage at VIN+ is less than the analog voltage at VIN-, the output of the comparator is a digital low level. When the analog voltage at VIN+ is greater than the analog voltage at VIN-, the output of the comparator is a digital high level.
The comparator has multiple input sources and various output options. This can vary with device selection.