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About the switching frequency of TPS54325Q1

tsuyoshi tokumoto
Expert 2630 points
Other Parts Discussed in Thread: TPS54325

Hi all,

  I'm disty in Japan.

  My customer is mass-producing the products including the TPS54325Q1 now.
  In their final inspection,the switching frequency of several hundred TPS54325Q1 chips
   were around 650kHz, but the frequency of a few chips were approximately 500kHz.
  The conditions of the final inspection are as follows.

    Vin:5V
    Vout:3.3V
    Iout:1.1A
    Temp:room temp

 I would like to understand whether that phenomenon is caused by the process variation or
  any other issue.

 Please let me ask four questions to explain about the switching frequency to my customer.
 
  ①Is the above switching frequency variation within the range of process variation?
  ②In the same temperature,what is the variation of switching frequency compared with
     Figure 8 or 9 on the data sheet by the process variation?
  ③What is the overall variation of switching frequency compared with Figure 8 or 9
     with including temperature conditions?
  ④If temperature rises, will the switching frequency become higher or lower?
 

Best regards.
Tsuyoshi Tokumoto

  • 0
    TI__Guru**** 191445 points
    TPS54325 does not have an internal oscillator. So there may be a large variation in switching frequency. 500 kHz vs 650 kHz is about 30 % which seems like a lot though. But as you can see from the graphs 100 kHz variation would not be unusual. Do you have the distribution data for the "several hundreds" of samples you mention?

    There may be some temperature data. I can look for it next week.

    So far as I know, this is not production tested so there will not be any lot to lot data available.
  • 0 in reply to JohnTucker
    Expert 2630 points

    Hello Tucker-san,

    Thank you very much for your prompt reply.

    I will request the distribution data for the "several hundreds" of samples
    from my customer because I have not it now.

    I’d appreciate it if you could send the temperature data to me,
    because I would like to understand the trend of TPS54325Q1 temperature characteristics.

    Best regards.
    Tsuyoshi Tokumoto

  • 0 in reply to tsuyoshi tokumoto
    TI__Guru**** 191445 points

    If I do have data it will be for the regular TPS54325, not Q1 version.

  • 0 in reply to JohnTucker
    Expert 2630 points

    Hello Tucker-san,

    I requested the distribution data for the "several hundreds" of samples
    from my customer.

    Would it be possible to have you send the data of process variation
    about the switching frequency to me?

    Thank you for your cooperation.

    Best regards.
    Tsuyoshi Tokumoto

  • 0 in reply to tsuyoshi tokumoto
    TI__Guru**** 191445 points
    I do not think we have any data strictly over process as this is not a tested parameter.
  • 0 in reply to JohnTucker
    TI__Intellectual 2590 points
    Hi Tokumoto,


    TPS54325 is not Q1 part. this part is DCAP2 control mode, the frequence should be change with Input, Vout votlage, output loading, it's also has ECO mode in light load condition. i am sorry we can't provide the data, even we test in mass product, it can just gurantee at one input voltage, output voltage condition, we can't gurantee all applicaiton.
    why custoemr cares about the frequecny so much? Current mode's freuqency is much good than DCAP.
    thanks!
  • 0 in reply to Eric Guo1
    Expert 2630 points

    Hello Eric-san,

    I'm sorry for the late response.
    I understand that you cannot provide the process variation data.
    It is the reason that my customer cares the switching frequency that my customer
    would like to understand whether that phenomenon is caused by the process variation
    or any other issue

    Currently,the switching frequency of five TPS54325Q1 chips were approximately 500kHz,
    and the switching frequency of remaining chips(several hundred kilo units) were
    in the range from 650kHz to 680kHz.
    The 500kHz chips and the other chips are measured with same conditions.
    Vin:5V
    Vout:3.3V
    Iout:1.1A
    Temp:room temp


    If the 500kHz switching frequency is within the process variation,the circuit board
    including the switching frequency 500kHz chip and the chip will be non-defective.
    If not,the circuit board or the chip may have any issue.

    We are going to evaluate the circuit board swapping the 500kHz chip for the 650kHz chip
    to cross-check on the middle of January,2016.

    If we have any issues,I will consult with you.

    Thank you for your cooperation.

    Best regards.
    Tsuyoshi Tokumoto