19.6.1.3 Selecting the Main Voltage Regulator

In Active mode, the type of the main voltage regulator supplying VDDCORE can be switched on the fly. The two alternatives are a LDO regulator and a Buck converter.

The main voltage regulator switching sequences are as follows:

  • The user changes the value of the Voltage Regulator Selection bit in the Voltage Regulator System Control register (VREG.SEL)
  • The start of the switching sequence is indicated by clearing the Voltage Regulator Ready bit in the STATUS register (STATUS.VREGRDY=0)
  • Once the switching sequence is completed, STATUS.VREGRDY will read '1'
The Voltage Regulator Ready (VREGRDY) interrupt can also be used to detect a zero-to-one transition of the STATUS.VREGRDY bit.