 Hello and welcome to this presentation of the STM32U5 voltage reference buffer. It covers the main features of this block, which creates a non-chip reference voltage. The Vref buffer, embedded in STM32U5 microcontrollers, provides a stable voltage based on an internal bank gap reference for use by both the analog to digital and digital to analog converters. When Vref buff is used as an internal voltage reference, it's output on the Vref plus pin in order to provide this reference to external devices. When an external voltage reference is implemented, the Vref plus pin is an input. STM32U5 Vref buff supports four different output voltages which are 1.5, 1.8, 2.048 and 2.5 volts. 1.5 and 1.8 volts are new with respect to the STM32U5. The output voltage is factory calibrated and trimming data is stored in the engineering option bits. At reset, and each time the voltage reference scale setting is changed, the calibration data is automatically loaded to the trim register. In the previous version of this module, it was necessary to copy the engineering option bits to the calibration control register by software. The Vref buff output pin Vref plus is available only on packages having 100 pins or more. In the LQFP48, UFQFPN48, LQFP64 and WLCSP90 packages, the Vref plus pin is double bonded with the VDDA pin and therefore the voltage reference buffer is not available and must be kept disabled. The STM32U5's analog to digital and digital to analog converters use this Vref buffer output. Please refer to the training modules for these peripherals for additional information.