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TPS82085/about out put ripple in TINA-TI simulation

Tsukui Yusuke
Guru 21930 points
Other Parts Discussed in Thread: TINA-TI, TPS82085

Hi,

Could you tellme about TPS82085 TINA-TI sim.
Will you check the attached file?
TPS82085 sim.pdf
When the simulation under the same conditions,
Output voltage ripple level is different in datasheet waveform.
Customers want to know the reason for this.
Could you give me your advice?

Best regards,
Yusuke/Japan Disty




  • 0
    TI__Mastermind 39210 points

    Yusuke-san,

    I created this design in WEBENCH and the ripple is around 7-8mV. The design is attached which you can export to TINA-TI. I am not sure what changes you have made that caused the ripple to increase to 50mV. Can you use the design sims below?

    https://webench.ti.com/appinfo/webench/scripts/SDP.cgi?ID=D09E0CC6CDB8E0C3

  • 0 in reply to Nikhil Gupta (Product Folder Models)
    Guru 21930 points

    Gupta-san,

    Thank you for your support.
    I attached below the simulation results of the export.
    (Circuit constants are not changed.)

    TPS82085 webench_design_3456224_1628.TSC

    I think the right is more of a result of Webench.
    Could you review the data?

    Best regards,
    Yusuke/Japan Disty

  • 0 in reply to Tsukui Yusuke
    Guru 21930 points

    Hi,

    Can I get the information?

    If you need more information or if  I should  clarify my comment ,

    please let me know.

    I’m so sorry to rush you but please support this.

    Best regards,

    Yusuke/Japan Disty

  • 0 in reply to Tsukui Yusuke
    TI__Mastermind 39210 points
    Yusuke-san,

    The component selection in WEBENCH is in accordance with Datasheet, thermal and other guidelines. If you are looking for component selection recommendations or reviews, it would be best to post this in the Non Isolated DC/DC forum.

    Regarding the ripple question, this depends on several factors (especially for hysteretic DCS controllers like this device). Since DCS devices do not have a fixed frequency oscillator inside, the frequency can be affected a lot by parasitic effects which are not captured in the spice models. Also, the output cap plays a part in frequency calculation especially at light loads where the light load mode depends on cap voltage being discharged with the load current to set the operating frequency. In WEBENCH, we include a typical derating on the cap for ceramic caps which may impact the frequency and ripple that you get and why it may be different from that you get from the standalone TINA-TI model.
  • 0 in reply to Nikhil Gupta (Product Folder Models)
    Guru 21930 points

    Gupta-san,

    Thank you for your information and support.
    I understand your explanation.

    However,    If the ideal conditions,
    I think the characteristic will be better than the graph of the data sheet

    Could you give me your advice for this point?

    Best regards,

    Yusuke/Japan Disty

    However,
  • 0 in reply to Tsukui Yusuke
    TI__Mastermind 39210 points
    Yusuke-san,

    Under ideal conditions, the frequency in the model could deviate in either direction compared to bench measurement for DCS devices. As I mentioned earlier, there are lot of factors (many secondary and tertiary effects) that affect this in real life which are not always captured in spice model. If you are looking at frequency related aspects, it would be best to follow Datasheet plot. By the way, the initial reply that i gave has results matching the Datasheet pretty closely.