8 Replies Latest reply: May 1, 2013 11:08 AM by KevinG Branched to a new discussion. RSS

    BF-548 Internal Regulator Use

    Varun-Blackfin

      According to BF548 EVK Manual, it states that internal regulator is being used on the EVK.

       

      But the VDDVR pin of the processor is tied to VDDEXT, which means that internal regulator is not being used and VDDINT regulator output resistor is also not populated on the board.

        • 1. Re: BF-548 Internal Regulator Use

          Hi,

           

          I have moved this discussion from the Blackfin Processors community to the Hardware Tools community. Please continue the discussion here.

           

          Regards,

          Craig.

          • 2. Re: BF-548 Internal Regulator Use

            Hi,

             

            I have spoken with the Hardware Team regarding this matter, and they advised that the EZ-KIT Lite uses the VDDVR pin as the input voltage reference for the internal voltage regulation circuit. The EZ-KIT Lite does use the internal voltage regulator - you will see that the resistor on the output of the external regulator circuit is not populated.

             

            Regards,

            Craig.

            • 3. Re: BF-548 Internal Regulator Use
              Varun-Blackfin

              Hi Craig,

               

              I missed something on this, pls. take a look at the following pics, datasheet says that if not using internal regulator tie VDDVR pin(F15 Ball) to VDDEXT, this is what is done to F15 pin of BF548 in EVK schematics, it does not mention the F15 as VDDVR pin, instead it is written as VDDEXT

              Below is the library of EVK

               

              BF548 EVK Library.bmp

              Below is the pin out of BF548 from datasheet

              BF548 Pinout.bmp

              Below is the voltage regulation paragraph of datasheet at page no 16 of datasheet:

              VDDVR Regulator.bmp

              Regards.

              • 4. Re: BF-548 Internal Regulator Use

                Hi,

                 

                In the version of the BF548 datasheet that was used when the EZ-KIT Lite was designed, it was labelled as VDDEXT.

                 

                Regards,

                Craig.

                • 5. Re: BF-548 Internal Regulator Use
                  Varun-Blackfin

                  Hi,

                   

                  Even if F15 ball is termed as VDDEXT initially but still the datasheet says that to use internal regulator of the device we have to use the following circuit given in datasheet at page-17  for VDDVR pin, but this is not done, instead F15 is connected to VDDEXT voltage rather than VDDINT produced on the board. Pls. help

                   

                  Internal Regulator.bmp

                  On page-32 of datasheet following is mentioned on point-13

                  VDDVR: This pin must always be connected. If the internal voltage regulator is not being used, this pin may be connected to VDDEXT Otherwise it should be powered according to the VDDVR specification. For automotive grade models, the internal voltage regulator must not be used and this pin must be tied to  V DDEXT

                  .

                  • 6. Re: BF-548 Internal Regulator Use
                    KevinG

                    VDDVR should be connected to the input voltage and not VDDINT. VDDEXT is 3.3V and is connected to VDDVR.  VDDVR and VDDINT are two separate signals.  The internal regulator uses VDDVR as the input voltage reference for the regulator and therefore it needs to be higher than the voltage that you want on VDDINT.

                     

                    The circuit on figure 6 has been followed.  If you look at the circuit on the top right of sheet 16 of the EZ-Kit schematic you will see that it is the same as the circuit listed in the datasheet.

                    • 7. Re: BF-548 Internal Regulator Use
                      Varun-Blackfin

                      Hi,

                       

                      Thanks for your reply.

                       

                      I want to know the sequencing related to VDDINT rail.

                       

                      Because EZ-Kit Lite is using internal regulator controlled through VROUT pin, so during power on reset how is power sequencing met because power sequencing on page-42 of Datasheet says that reset should be de-asserted only after all Power domain rails are  stable. So how can VDDINT be generated as it is controlled through VROUT pin, but processor is still in reset?

                       

                      So does VROUT pin belong to always powered domain?

                      • 8. Re: BF-548 Internal Regulator Use
                        KevinG

                        The VROUT rail is powered regardless of the state of the RESET signal.  You want all rails to be valid before de-asserting reset so that all IC on the board are in a know good state when the BF561 begins it boot process.