Query about internal SMPS of STM32H757

[taj]

I am trying to apply this configuration to my STM32H757 MCU where I am making a development board. here few things confuses me. 
1. I have selected this configuration for better efficiency + noise performance. guide me if I am wrong
2. What is the VDD External it seems like another input other than VDD.

[Gyessine]

Hello, @taj 
Despite SMPS being very efficient, they are known to be noisier. You can run some tests, and if you find that your configuration is noisier than desired, there are low-noise SMPS designed to have small ripples.

For more information about power supplies, can refer to this WIKI

 BR

Gyessine

[Bouraoui Chemli]

Hello, 

1) This allows to reduce the noise on the digital domain, but we did not observe a major noise from SMPS that could impact the application.

2) VDD external, is SMPS output that you can use for another device to power it at 1.8V or 2.5V depending on SMPS output configuration

Best regards,

Bouraoui