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TPS61020: Down Regulation

Y.Ottey
Mastermind 6145 points
Part Number: TPS61020
Other Parts Discussed in Thread: TPS61025

Dear TI Team

I would like to ask about Down Regulation mode of TPS6102x.

When Vin becomes higher than Vout, it is described that the device operates as the Down Regulation as follows.

Please answer the following questions about the operation of Down Regulation when using Vin=0.9V to 6.4V, Vout=3.3V.
1. Is there any problem if the operation time of Down Regulation is longer than the operation time of original step-up DCDC (Vin is lower than 3.3V)?
2. Is it possible to use the same idea as that of LDO for heat generation when operating under the Down Regulation?
3. Our customers are considering the TPS61020 and TPS61025, but I have received a request from them to support voltages below Vin=0.85V. When I searched, I couldn't find any products that correspond to the voltage lower than Vin=0.85V in the step-up DCDC and the buck-boost DCDC with the function of Down Regulation made by TI.
Do you know a product that meets the above conditions?

Best Regards,

Y.Ottey

  • 0
    TI__Guru 58225 points

    Hello Y.

    1. No, if you make sure that the converter is able to handle the power dissipation by adding enough copper to the board.

    2. Yes, at the end the part is oprating as a linear regulator.

    3. Please get some more details on the need of 6.4V on the high end and 0,85V on the low end. Most of the low voltage devices have an upper limit of 5.5V. For both boost and buck-boost devices. Maybe we can recommend 2 devices if the ranges can be reduced.

  • 0 in reply to Brigitte
    Mastermind 6145 points

    Dear Brigitte

    Thank you for your reply.

    I understand that operation in Down Regulation mode is same as linear regulator.

    I would like to ask following question.

    1.If TPS61020(TPS61025) calculates the heat loss under the condition of Vin=6.4V, Vout=3.3V, Iout=10mA, we think that it can be estimated by the following calculation, but other factors should be added. do you have? (E.g. heat generation due to IC self-consumption current)

    Regards,

    Y.Ottey

  • 0 in reply to Y.Ottey
    TI__Mastermind 46905 points

    Hi Y.Ottey,

    please refer to https://www.ti.com/lit/an/slva199/slva199.pdf to understand the down mode operation. the equation you used is not correct.

  • 0 in reply to Jasper Li
    Mastermind 6145 points

    Hi Jasper,

    Thank you for your reply.

    I understand about operation and power dissipation of Down Regulate mode.

    I would like to ask following question.

    The material you introduced has the following formula.

    When calculating Pd during Down Regulation, should it be calculated by substituting Vt=1V considering the worst case? (Because the threshold of Vt is 1V in the document)

    Regards,

    Y.Ottey

  • 0 in reply to Y.Ottey
    TI__Mastermind 46905 points

    Hi Y.Ottey,

    yes, the Vt is approximately 1V