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TPS61030: TPS61030 TINA-TI Transient Reference Design issues

Alberto Villa
Prodigy 130 points
Part Number: TPS61030
Other Parts Discussed in Thread: TINA-TI

I am having unexpected responses when simulating the TPS61030 TINA-TI Transient Reference Design (file slvm099.tsc). I have updated TINA-TI to the latest edition (9.3.200.277 SF-TI) but the problem remains.

This is what happens:

a) It is stated that "This application has been corner tested for input voltage ranges: 1.8V to 5V and Iload: 10mA to 1A in steady state".

b) If I proceed with a 3 ms long transient simulation as recommended and without changing anything (3.3 Vin; 5 Vout with 250 mA of current into the 20 Ohm Rload) I get exactly the same results as those depicted on the schematic editor page.

c) But when I increase the output current by reducing Rload the things start going wrong. For instance, with Rload = 10 Ohm (expected 500 mA with Vout = 5 V) the output transient changes completely and the voltage Vout settles at 3.24 V (checked up to 30 ms).

d) With Rload = 5 Ohm (for a 1 A current @ 5V) the simulation takes even longer, and Vout settles at 2.45 V.

What am I missing?

Thank you very much in advance and best regards.

Alberto Villa

  • 0
    TI__Guru 65310 points

    Hello Alberto,

    Which input voltage is applied? Maybe the device is getting into current limit.

  • 0 in reply to Brigitte
    Prodigy 130 points

    Hello Brigitte,

    THank you for your reply.

    I have changed only the load resistance, from 20 Ohm to lower values. The input source Vin is still the original one, 3.3 V. The datasheet states that this device is capable of delivering 1 A at 5V output from a 1.8 V source, and as I remembered before this is also written in the text block of the simulation page, just below the schematic. Hence it should work, as long as the model is OK.

    By the way, I've also tried to increase the input voltage up to 4.2 V (a fully charged LiPo cell). The Vout reaches approx. 3.32 V with a current of about 680 mA through the 5 Ohm Rload.

    I wonder if I am missing some specific settings, but I don't see where...

    Alberto

  • 0 in reply to Alberto Villa
    TI__Mastermind 46905 points

    Hi Alberto,

    it seem the device stay at pre-charge phase, this could happen if the loading is too large before the IC finishes startup.

    please add large load after the IC finishes startup, which means VOUT reaches 5V.

  • 0 in reply to Jasper Li
    Prodigy 130 points

    Hi Jasper,

    thank you, but are you sure? 

    This is the first time I hear about such an unusual way of simulating a switching converter. I've never had to proeceed in this way before.The model should work also when started with the maximum rated load, as it may happen during normal operation.

    In fact, the text box under schematic tells that "3. This application has been corner tested for input voltage ranges: 1.8V to 5V and Iload: 10mA to 1A in steady state." Furthermore, it does not mention the necessity of increasing the load after the startup phase.

    Regards,

    Alberto

  • 0 in reply to Alberto Villa
    TI__Mastermind 46905 points

    Hi Alberto,

    sorry for missing this thread.

    it is boost converter integrating short circuit protection. to implement the short circuit protection in the boost topology, the current limit must be smaller during startup when the VOUT is still lower than VIN. a traditional boost circuit doesn't support short circuit protection.

    this behavior is mentioned in page 10 of datasheet. it is not convenience to describe too detail in the simulation file.

  • 0 in reply to Jasper Li
    Prodigy 130 points

    Thank you very much indeed, Jasper.

    So, does it mean that in practice this DC-DC converter cannot be switched on with full load applied?

    Alberto

  • 0 in reply to Alberto Villa
    TI__Mastermind 46905 points

    Hi Alberto,

    please enable the device with no load or small load firstly, then add the full load after the startup finishes.

  • 0 in reply to Jasper Li
    Prodigy 130 points

    Thank you very much, Jasper.

    I have added a time-controlled switch, and now the simulation works! The case is closed.

    I warmly suggest to add a note on the simulation page to remember what you told me.

    Best regards,

    Alberto