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TPS55340-Q1: TPS55340QRTERQ1 - Reason for the oscillation of the inductor current when simulated in TINA TI

Part Number: TPS55340-Q1
Other Parts Discussed in Thread: TINA-TI, TPS55340


The boost converter TPS55340QRTERQ1 is used in the design to charge the bulk capacitor to 32V by supplying 9-19V input. When simulated in TINA-TI, we are observing that the inductor current is beginning to oscillate after remaining in the current limit for 43ms. The oscillations begins at 298ms(refer the simulation result). Please help us with the reason for the occurrence of the oscillations.

This post contains two attachments:

1)Circuit schematics in TINA 

2)Simulation result: The result contains the

1) inductor current (IL1)

2)Voltage measured at the bulk cap (VCAP)

  • Hi Sri,

    Thanks for considering TPS55340.

    1. Since you have a large cap, try increase the SS cap to avoid long time current limit.

    2. For the ringing issue, could you show the SW voltage waveform? Also zoom in waveform of IL1 and SW?



  • Hi Yinsong,

    Please find the screenshot of the  inductor current and SW node and Vout curve (ignore the striked curves). I think it will he helpful for you if i provide the

    simulation result in .tdr format but i couldn't upload it. Is there any way I can send you the simulation result in .tdr format? Please let us know if you need

    more information for finding the reason for ringing

    Vout curve:

  • Hi Sri,

    No problem, I think we can do it this way first.

    It looks like it is not stable but recovers later.

    1. Could you show the COMP?

    2. What is the phase margin you have?


  • Hi,

    1)COMP pin:

    2)Phase Margin:

    We are yet to simulate for phase margin but we would like the system to stable
  • Hi Viswa,

    It goes unstable during the startup.

    You can try

    1. increase SS cap to slow down the startup so that the inductor current does not hit the current limit

    2. change different compensator to have a higher phase margin. the phase margin can be estimated by the quick start calculator (in the product page\design & development)