• State TI Thinks Resolved
  • Locked Locked
  • Replies 3 replies
  • Answers 1 answer
  • Subscribers 80 subscribers
  • Views 683 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.

TMS320F28377S: F2837xS "Power Sequencing" Specification

ay0689_3
Expert 1085 points
Part Number: TMS320F28377S

Hello,

we developed prototype board refered to LAUNCHXL-F28377S as the reference design.

We are checking F28377S data sheet(SPRS881G) specifications in relation to the errata.

Please see the followings. 

Q1: How should we consider the ramp spec between VDD and VDDOSC?

What is the definition of "at the same time"?  

I measured the voltages of both VDD and VDDOSC on our LAUNCHXL-F28377S board by OSCILLOSCOPE as follows. 

As Q2, Does LAUNCHXL-F28377S meet the 5.9.1.3 VDD requirement spec on F28377S datasheet? 

Best regards,

ay0689

  • 0
    TI__Mastermind 28275 points
    Hi ay0689,

    There is no contradiction between the two statements that i can see. The first statement is telling you what you should do. The second statement is telling you what will happen if you don't do the first statement. In other words, VDDOSC and VDD should be powered on/off at the same time. However, if you aren't able to do that, you risk the condition mentioned in the errata happening.

    Q1. "At the same time" means VDDOSC and VDD should have the same ramp rate and powered on simultaneously. Now, we recognize this might be difficult since they will be different supplies but you should keep the two ramp rates as close as possible. You can make the ramp rate of VDD slightly higher than VDDOSC but not to the point where VDD ends up being 0.3V greater than VDDOSC.

    Q2. Does the F28377S-LP meet the requirement? Yes and No. Now keep in mind that this is a new finding and the F28377S-LP was designed and released well before this. I haven't measured the ramp times of the F28377S-LP myself but i have no reason to doubt your measurements. However, we believe most customers that use the F28377S device use an external clock: crystal, oscillator etc so should be unaffected by this. The F28377S-LP contains an external clock source. The advisory only affects the internal oscillators, INTOSC.
  • 0
    TI__Mastermind 28275 points
    Hi ay0689,

    Do you have anymore questions on this?
  • 0 in reply to Frank Ankapong
    TI__Mastermind 28275 points
    Hi ay0689,

    It's been a while since we heard from you so I'm going to assume your questions were answered and will be closing this thread. If that's not the case, feel free to reject the answer and reply to this post or create a new thread if this one locks out due to inactivity.