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TPS562211: Not getting proper simulation results for light load in Pspice for TI

Siddhi Sawant
Intellectual 325 points
Part Number: TPS562211

Hello team, 

I simulated TPS562211 for Vin=12V, Vout=3.3V, Iout= 0.5A

Accordingly, I changed the inductor value which is  calculated using Equation 12 for Lmin(circuit is attached for reference).

So Lmin=15.95uH which is approx 16uH. After simulating it for above values, I got results as attached below. It is not getting simulated properly.

Whereas, for 4.7uH, the circuit is working properly for same load and I am getting correct results.

So, will the circuit work or not for selected value of inductor?

Thanks,

Siddhi

  • 0
    TI__Expert 8100 points

    Hi Siddhi,

    I will check the simulation and give you reply later!

    BRs

    Zixu

  • 0
    TI__Expert 8100 points

    Hi Siddhi,

    I tried simulating pspice project downloaded from ti.com. The steady state simulation and startup simulation work well from my side and following figure shows the result

    I suppose there may be some inappropriate setting for the simulation file making startup simulation works in abnormal status.

    From the steady state simulation, it shows large output ripple in Vout, which could be caused by loop instability. Large inductor could cause control loop instability.

    Please refer to recommended LC table shown in datasheet to select inductor and output capacitor.

    BTW, may I check your settings in the calculation formula of inductor? I am curious about the process for getting calculated result of 16uH.

    BRs

    Zixu