• State
  • Locked Locked
  • Replies 1 reply
  • Subscribers 83 subscribers
  • Views 246 views
  • Users 0 members are here
Support feedback
Options
Options
Related

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.

Original question:

TMS320F28335: PLL cannot lock

TMS320F28033: PLL cannot lock

Emma Wang
Expert 5250 points
Part Number: TMS320F28033


Hi expert,

I have a customer meet similar issue like this post.

The device is F28033. It is occasionaly happened.

They also stuck at PLLLOCKS status check

they also use external oscillator. so they check the oscillator waveform.

it is normal.

so they want to know.

1. If the external oscillator frequency abnormal cause the PLLLOCKS status failed. Can PLLLOCKS turn to 1 after the oscillator get worked normally?

2.Except the oscillator frequency abnormal. what other condition will cause the PLLLOCKS status failed?

BR

Emma

  • 0
    TI__Guru* 95315 points
    Emma Wang said:
    1. If the external oscillator frequency abnormal cause the PLLLOCKS status failed.

    Malfunction of an external oscillator is generally rare. However, if the output from that osc is abnormal, there is a possibility of the PLL not locking.

    Emma Wang said:
    Can PLLLOCKS turn to 1 after the oscillator get worked normally?

    Yes, provided the source of the problem is indeed the external oscillator.

    Emma Wang said:
    2.Except the oscillator frequency abnormal. what other condition will cause the PLLLOCKS status failed?

    There could be a problem in the PLL itself. It is hard to tell without extensive experimentation and testing.  Knowing the answers to the questions below would help in isolating the issue: 

    1. How long has this design been in production?
    2. In how many boards is this problem seen? i.e. is the problem isolated to a single board or is this seen in multiple boards?
    3. How often is the problem observed? For example, if you power-up the board 50 times, how many times is the problem seen?
    4. Is it possible to reproduce the problem easily?
    5. Is the problem seen if INTOSC1 is used as the clock source?
    6. Is this seen in a device that has been working fine for some time? If so, how long?
    7. Is there any temperature dependency to the issue? i.e. does the rate of problem occurrence vary based on the ambient temperature?