• State Resolved
  • Locked Locked
  • Replies 2 replies
  • Answers 1 answer
  • Subscribers 82 subscribers
  • Views 125 views
  • Users 0 members are here
Support feedback
Options
Options
Similar topics

This thread has been locked.

If you have a related question, please click the "Ask a related question" button in the top right corner. The newly created question will be automatically linked to this question.

TMS320F28375S: TMS320F28375SPZPQ Microcontroller Power On Sequence Datasheet Vs Evaluation Board LAUNCHXL-F28379D

Aaron_Rangel
Intellectual 420 points
Part Number: TMS320F28375S
Other Parts Discussed in Thread: LAUNCHXL-F28379D

Hello,

I have seen in the TMS320F28375S microcontroller's datasheet that Vddosc and Vdd must be powered on and off at the same time. There is also an advisory to check this in the datasheet.

As Vddosc is 3.3-V on-chip crystal oscillator X1 & X2 and the two zero-pin internal oscillators INTOSC and Vdd is 1,2V digital logic power pins, I guess that Vddio (3V3 digital I/O power pins) and Vdd (1,2V digital logic power pins) should be started at the same time.

On the other hand, after checking the EVAL BOARD LAUNCHXL-F28379D schematics, I see that 3V3 (VDDOSC, VDDA, VDDIO) is the source for 1V2 (VDD) voltage rail (3V3 Dc Dc Step-Down to 1V2).

So, I'm wondering whether I'm understanding well this datasheet recommendation or not.

Should 3V3 and 1V2 rails start at the same time or not? Should I follow the EVAL BOARD schematic or not?

Regards,

  • 0
    TI__Guru* 95315 points

    Aaron,

                    The datasheet guideline always takes precedence. The LaunchPad design strikes a fine balance between cost, board space, foot-print compatibility (with previous LPs) etc. It is a platform meant for evaluating the MCU. Not ramping VDD along with 3.3v impacts the internal oscillators (INTOSCn)+ and that too at high temperatures. Many designs use an external crystal since INTOSC accuracy may not meet system requirements.

  • 0 in reply to Hareesh Janakiraman
    Intellectual 420 points

    Hello Hareesh,

    Thank you very much for your reply and clarification.

    Datasheet takes precedence, we will proceed in that way and will ramp VDD along with 3V3 in our design.

    Regards,