AVR128DB48 Using the Internal Opamp as Regulated Power Supply for MVIO

A new feature introduced in the AVR® DB family is the Analog Signal Conditioning (OPAMP) peripheral. In this example, the OPAMP is used as an adjustable power supply. This eliminates the need for an external power supply for a second voltage domain. One op amp is configured as a voltage follower and code examples for four scenarios are presented:

1. Voltage reference using the internal resistor ladder.
2. Voltage reference using an external resistor.
3. Voltage reference using the internal DAC.
4. Monitoring voltage level with the internal ADC.

Related Documentation

• AN3636 - AVR128DB48 Using the Internal OPAMP as Regulated Power Supply for MVIO
• AVR128DB48 device page
• AVR128DB48 Curiosity Nano User Guide

Software Used

• MPLAB® X IDE 5.40 or later
• MPLAB® XC8 2.20 or later
• MPLAB® X AVR-Dx_DFP version 1.4.75 or later
• For the Atmel Studio version of these projects, please go to this repository

Hardware Used

• AVR128DB48 Curiosity Nano
• Two resistors (values based on desired voltage level)

Setup

• Enable MVIO powered by internal op-amps on the development board, see application note for each respective scenario
• Enable Dual Supply mode in the System Configuration 1 (SYSCFG1) fuse

Operation

• Connect the AVR128DB48 Curiosity Nano to a computer using a USB cable
• Clone the repository or download the zip to get the source code
• Open the project folder you want to run with MPLAB X
• Compile and run the code

Conclusion

After going through this example you should have a better understanding of how to set up the OPAMP peripheral as a regulated power supply.