5.4.5 Operational Amplifiers (OPAMP)

Some AVR and PIC32CM MCUs have integrated Operational Amplifier (OPAMP) peripherals designed for flexible, low-power analog signal conditioning. The OPAMP peripherals provide up to three individually configurable opamps with rail-to-rail inputs, internal resistor ladders for feedback and gain control, and a wide range of selectable configurations. Both AVR and PIC32CM OPAMPs enable complex analog signal processing with minimal or no external components. Table 5-18 shows a comparison of features between the two.

Table 5-18. AVR® and PIC32CM OPAMP Features
FeatureAVR® OPAMPPIC32CM OPAMP
Number of Op AmpsUp to threeUp to three
Input Selection

I/O pins, DAC, ground

VDD/2

Other OPAMPs

Internal resistor ladder

I/O pins, DAC, ground

Other OPAMPs

Internal resistor ladder

Output Selection

I/O pins, ADC, AC

Other OPAMPs

I/O pins, ADC, AC

Other OPAMPs

Internal Resistor LadderWith multiplexers for top/bottom/wiperConfigurable for internal feedback
Configurations

Stand-alone

Unity gain buffer

Inverting/non-inverting PGA

Cascaded PGAs

Instrumentation amplifier

Stand-alone

Unity gain buffer

Inverting/non-inverting PGA

Cascaded PGAs

Instrumentation amplifier

Comparator with hysteresis

CalibrationOffset/gain calibration using ADCOffset/gain measurement with ADC
Power ModesLow-power, event-triggered operationFour selectable modes (speed vs. power), on-demand start-up
Event System IntegrationIncludes dump mode for signal integrationOn-demand start-up for ADC/AC
Special Features

Internal timer for a READY event

Dump mode

Voltage doubler

Programmable hysteresis