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WEBENCH® Tools/TPS63000: When driving TEC, the work is abnormal in BUCK mode

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Replies: 17

Views: 173

Part Number: TPS63000

Tool/software: WEBENCH® Design Tools

When driving TEC, it was abnormal when working in BUCK mode. The whole circuit input 3.3v voltage and output 1.3v-5.4v voltage range.TEC generates 300-400ma current;At present, when the circuit is in boost mode, it works normally. In BUCK mode, the Vfb voltage is abnormally increased.

For example, set output 1.3v, actual Vout output 2.2v, Vfb= 0.56v;May I ask how he caused it? How can I modify the circuit to solve it? Thank you

  • Dear Customer,

    thank you for using our device.

    the picture of the TPS63020 is just an example, you are using the TPS63000, right?

    What is your voltage at DAC_TEC during operation?

    regards,

    Moritz

  • In reply to Moritz.:

    Yes, I use TPS63000, the input of DAC is 2.4v, corresponding VOUT should be about 1.3v, the actual value is 2.2v, VFB is about 0.46v;The boost mode is normal

  • In reply to boer.deng:

    please use this http://www.ti.com/lit/an/slva251/slva251.pdf

    it will help you to calculate your resistor values.

    regards,

    Moritz

  • In reply to Moritz.:

    I have calculated according to the manual, but the calculation still fails to work properly. Is there any other reason?thank you

  • In reply to Moritz.:

    Can not be the VOUT end has the irrigation current appears the problem, may I ask the irrigation current most big how many?

  • In reply to boer.deng:

    Hi,

    can you please share your calculated results?

    what do you mean by 'irrigation current'?

    regards,

    Moritz

  • In reply to Moritz.:

    Plan 1: R1=845K;R2 = 100 k;R3 = 470 k
    Plan 2: R1=1M;R2 = 120 k;R3 = 560 k
    Plan 3: R1=100K;R2 = 12 k;R3 = 56 k
    Plan 4: R1=51K;R2 = 6. 2 k;R3 = 27 k
    According to the manual SLVA251 calculation have tried or failed.
  • In reply to boer.deng:

    Can you please also share the voltage assumptions you made for your calculation?

  • In reply to Moritz.:

    VOUT is set as 1.2v ~ 5.5v, and the voltage of DAC is 0V ~ 2.4v

  • In reply to boer.deng:

    did you take the accuracy of the resistor into account? If teh value is not exactly as calculated you will get deviation.

    According to the app note posted in the thread above, there will be an offset. You need to compensate that offset with your DAC voltage.

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