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UCC25600: UCC25600 Tina Simulation Model

Dilip Ramgir
Prodigy 90 points
Part Number: UCC25600
Other Parts Discussed in Thread: TL431

Tool/software:

Hello,

I'm using UCC25600 for LLC converter with the following specifications:-

Input Voltage :- 665Vdc

Switching Frequency :- 100kHz

Output Voltage :- 55V

Output Power :- 150W

I'm using Tina model of this to simulate it but the output voltage doesn't reach 55V as per requirements. 

1) I've set the Tank values as per calculations giving in SLUP263 document.

    Considering Q=0.56, Lm/Lr=5, Dead time :- 500nsec

2) I've set the feedback resistors such that at 55V output, I get 2.5V reference at TL431.

3) Can you also help me out with the component values for Over Current protection.

I've attached the Tina simulation file as well FYR.

slum425_55V.TSC

Thanking you in advance, 

Regards,

Dilip R

  • 0
    TI__Guru* 85516 points

    Hello,

     

    I cannot fin SLUP263 on ti.com.

     

    If your output is not regulating your transformer’s Lm, turns ratio and Lm/Lr ratio is probably not setup correctly.  You should be able to use the excel tool to calculate require Lm, turns ratio and Lm/Lr ratio.  You can find it at the following link.

    https://www.ti.com/tool/download/UCC25600-DESIGN-CALC

     

    Regards,

  • 0 in reply to Mike O'
    Prodigy 90 points

    Hello Mike,

    I've attached SLUP263 and the Calculation sheet as well FYR.

    I didn't get the desired results in Tina TI simulations even after using the calculation sheet of UCC25600.

    Below are few observations which shows that excel sheet's values does not match the SLUP263 equations:-

    1. As per equation (19) in SLUP263 considering Mg=1, the value of n=6 but the excel sheet gives as 7.2 (row no.23).
    2. I have set the Lm/Lr ratio i.e. 'm' as '5' in the sheet but the values of Lm/Lr = (1544uH/679.4uH) = 2.27 which doesn't match with the desired 'm'.

    Regards,

    Dilip R

    3225.slup263.pdf     sluc146.pdf

  • 0 in reply to Dilip Ramgir
    TI__Guru* 85516 points

    Hello,

     

    The inquiries will be evaluated in the order they have been received.

     

    Regards,

  • 0 in reply to Mike O'
    TI__Guru* 85516 points

    Hello,

     

    If your turns ratio is correct and you Lm and Lr ratio are correct you should be able to get the desired output voltage. 

     

    So, there are one or two things stopping from you regulating the output.

    1. Your switching frequency does not go low enough to get the gain you need.
    2. Your designs minimum switching frequency is set below fpp. This will cause the design to latch.

     

    To fix these issues just requires re visiting the RT setting and the feedback. To ensure you have the frequency range you need.  You need to be able to get fpp as the minimum frequency. If it goes below that you could latch.  If the frequency can go low enough you can achieve the gain you need.

     

    Regards,