Introduction
The applicable STM32xx devices (see Table 1) embed a very precise buffered reference voltage VREFBUF which can be used
either as a voltage reference for internal peripherals like ADC, DAC or externally through the VREF+ pin.
The purpose of the VREFBUF peripheral is to provide an accurate reference voltage with limited changes over temperature,
supply variations or product lifetime.
VREFBUF peripheral has several features like the output voltage reference scale selection, output voltage reference tuning/
trimming or output mode control in order to use an internal or external reference.
VREFBUF structure is based on low drop output regulator design with a compensation circuitry to optimize its accuracy within
the application environment including the current load on VREF+.
Table 1. Applicable products
Type Product Series/Lines(1)
Microcontrollers
STM32L4 Series
STM32L4+ Series
STM32L5 Series
STM32WL Series
STM32H7 Series
STM32G0 Series
STM32G4 Series
STM32WBx5 Line
STM32U5 Series
STM32H5 Series
Microprocessors STM32MP1 Series
1. This application note applies only to products with:
• presence of a VREFBUF peripheral
• VREF+ ball/pin not internally connected to VDD nor VDDA.
Refer to product datasheet.
VREFBUF peripheral applications and trimming technique
AN5690
Application note
AN5690 - Rev 1 - September 2021
For further information contact your local STMicroelectronics sales office.
www.st.com
1General information
This document applies to STM32 Arm®-based microprocessors and microcontrollers.
Note: Arm is a registered trademark of Arm Limited (or its subsidiaries) in the US and/or elsewhere.
AN5690
General information
AN5690 - Rev 1 page 2/18
