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BQ25713: 關於BQ25713 造成的noise聲音.

Nicholas Shih
Prodigy 120 points
Part Number: BQ25713

關於BQ25713, 因為我們發現好像當插入輸入時,有機率形成下面的波型.

造成有音頻出現.因為這個輸入到BQ25713的電流形成了約2.7-2.8k的週期.

客戶希望我們協助釐清這個問題的發生原因.不然可能會影響到MP時程. 

看是否有相關想法,對於這個現象.畢竟不希望noise發生.

 

CH1: BQ25713的輸入high side MOS 

CH2: BQ25713的輸入low side MOS

CH4 BQ25713的輸入電流波型,

CH1: BQ25713的輸出high side MOS(VSYS端) 

CH2: BQ25713的輸出low side MOS(VSYS端) 

CH4 BQ25713的輸入電流波型,

發出聲音時的bq25713暫存器狀態.

BQ25713開關的原理圖示.主要標示前幾張的示波器圖開關腳位

  • 0
    TI__Genius 11385 points

    Hi Nicholas,

    It shouldn't be in the audible range if EN_OOA is enabled. Can you put your design and the EVM under the same operating conditions and check switching frequency? Does it only occur during startup or it occurs at steady state as well?

    Thanks and I hope this helps,

    Peng

    *Please press "This Resolved My Issue" on the thread if my answer is satisfactory

  • 0 in reply to Pengzhao Zhu
    Prodigy 120 points

    Hi Pengzhao,

    看起來應該是輕載的時候(大約在1.04-1.37A之間),

    這個情形必須要串接兩台以上的BQ25713就會發生.

    單一台是不會發生的.

    下面這個波型是串接兩台測試情況和輕載(1.21A)的結果.

    但我們應用有可能串接四台產品.所以總共有四個BQ25713會串接.

    此時若輕載可能就會讓人耳有機會聽到noise聲音.

    所以客人要我們查明為何會有聲音.

    在我看來BQ25713的開關切換造成這樣的結果.

    看起來是很多小三角形在切換形成更低頻的三角波.如上圖所示.

    但我手邊並沒有EVB兩塊可以實驗.你們是否可以協助確認是否會這個問題.

    基本上我們都有enable OOA.

  • 0 in reply to Nicholas Shih
    TI__Genius 11385 points

    Hi Nicholas,

    What do you mean "串接"? How are you guys concatenating it? Can you guys show a block diagram?

    Here is the link to order EVM:

    https://www.ti.com/store/ti/en/p/product/?p=BQ25713EVM-017

    Thanks and I hope this helps,

    Peng

    *Please press "This Resolved My Issue" on the thread if my answer is satisfactory

  • 0 in reply to Pengzhao Zhu
    Prodigy 120 points

    Hi Pengzhao,

    I showed a block diagram in my last reply.

    Basically, our product includes your BQ25713+battery+buck-boost IC.

    BQ25713 is the input terminal. Another buck-boost IC is the output terminal.

    Then connect a same product in series. Finally, add E-load. As shown below.

  • 0 in reply to Nicholas Shih
    TI__Genius 11385 points

    Hi Nicholas,

    If it doesn't happen with one BQ25713 and you have a buck-boost in between. My thought is that it is a system issue and I would suggest you take a look at the buck-boost IC you are using. I would first isolate the problem to a root cause first and find out which particular set of combination causes this to occur. For example, try only one BQ25713 + buck boost and see if it occurs. Add more or subtract ICs until you can use the minimum amount of components to replicate the issue.

    If BQ25713 is the origin of the problem, then it will occur with one IC as well.

    Thanks and I hope this helps,

    Peng

    *Please press "This Resolved My Issue" on the thread if my answer is satisfactory

  • 0 in reply to Pengzhao Zhu
    Prodigy 120 points

    Hi Peng,

    It seems that basically light load will happen.

    As shown in the figure below, can you explain why?

    It seems that the two input switches (HB_HDV1 and HB_LG1) cause the current to oscillate.

    Customers have responded that they will hear noise when the battery is almost full.

    Bq25713 should also switch between PFM and PWM.

    Is it because of the noise caused by PFM?

  • 0 in reply to Nicholas Shih
    TI__Genius 11385 points

    Hi Nicholas,

    No, PFM will not cause the audible noise. The FSW in PFM mode is limited to 25 kHz which is above the audible range. Recommend to isolate devices in your system. If the problem originated from BQ25713, it will occur at one as well and you do not need to concatenate two or more. 

    Thanks and I hope this helps,

    Peng

    *Please press "This Resolved My Issue" on the thread if my answer is satisfactory

  • 0 in reply to Pengzhao Zhu
    Prodigy 120 points

    Are there any changes to the external resistor or capacitor parameters of COMP1&2 of BQ25713?

  • 0 in reply to Nicholas Shih
    TI__Genius 11385 points

    Hi Nicholas,

    The COMP1/COMP2 values seem to be the same as the EVM. 

    Thanks and I hope this helps,

    Peng

    *Please press "This Resolved My Issue" on the thread if my answer is satisfactory

  • 0 in reply to Pengzhao Zhu
    Prodigy 120 points

    I mean, have TI changed it?
    Although the parameters of EVB are the same as mine. Has it been changed later?

  • 0 in reply to Nicholas Shih
    TI__Genius 11385 points

    Hi Nicholas,

    No, we did not change it. It is the same.

    Thanks and I hope this helps,

    Peng

    *Please press "This Resolved My Issue" on the thread if my answer is satisfactory