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TPS24750: Unencrypted Spice Model?

Zeki Sisman
Intellectual 320 points
Part Number: TPS24750
Other Parts Discussed in Thread: TPS25982

Hi,

I am designing a circuit with TPS24750 and I would like to simulate my design. However only model available on its webpage is the encrypted PSpice model. Do you have an unencrypted model so I can import it to other simulators?  Or if it has to be encrypted for your IP purposes, do you have a Tina TI model? 

Thanks,

Zeki S.

  • 0
    TI__Guru* 95801 points

    Hi Zeki,

    Thanks for reaching out!

    Have you looked at TPS25982 device, which is fully integrated device and offers better performance over TPS24750.

    Unencrypted model can be shared only if your organisaton has NDA with TI. Can you please check on that ?

    BR, Rakesh

  • 0 in reply to Rakesh
    Intellectual 320 points

    Hi Rakesh,

    Thanks for the quick reply. I have seen TPS25982 however I had ruled it out since I need a current limit around 1A (±10%) and the datasheet of TPS25982 says the limit can be set between 2-15A. Do you know if TPS25982 can provide 1A limiting? If so then I can also go for that option.

    I also need to ensure the drop is as low as possible within full load range so I need a device with very low Rds. That's why TPS24750 looks like a good candidate. 

    I will check if my company has an NDA wit TI. But do you at least have encrypted Tina TI model for this part? That'd be great too.

    Edit:

    Rakesh I installed trial version of PSpice and started simulating however I am having trouble with the result I'm getting. My component values are:

    • Rsense = 22mΩ,
    • RImon = 1.2kΩ,
    • Rset = 39Ω,
    • RProg = 5kΩ.

    So I am setting my current limit to 1A, whereas the fast trip limit is at 2.72A. I set my load to 3Ω, and Vin = 5V (1.66A load). I want to see the startup behavior under a load heavier than the set limit but less than the fast trip.

    It is my understanding that with this setup, during startup the IC should fully turn on and after the time limit it should trip. However in the simulation I see that the IC does not fully turn on, but in fact regulates the current to the Ilimit value of 1A. Output stays stable at 3V and after the time limit the IC trips. During this interval the dissipation on the IC is (5V-3V)x1A = 2W. So I believe it should not be regulating for constant power. In the datasheet it says that start-up with shorted output will be controlled by power limiting loop. However my set power limit is 25W which is much higher than 2W. Then why does it not fully turn on at first? Am I missing something?

    Regards, Zeki

  • 0 in reply to Zeki Sisman
    TI__Guru* 95801 points

    Hi Zeki,

    TPS25982 can provide current limiting at 1A setting but the accuracy would be around 25%. So, you may need to proceed with TPS24750.

    During startup, TPS24750 starts regulating the current to Minimum of (Plim/Vin, Ilimit). For your 1A Ilimit setting and startup load of 3Ohm, the Vout =1A*3Ohm =3V

    You either need to increase Ilimit to start 3Ohm load or enable the downstream load using 'power good' output of the TPS24750.

    Unfortunately, we don't have TINA model for this part.

    Best Regards, Rakesh