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TPS61178: Design question

user5248878
Prodigy 20 points
Part Number: TPS61178
Other Parts Discussed in Thread: TPS61022

Tool/software:

Is TPS61178 suitable for the following designs?
Vin = 3V to 4.2V
Vout = 5V/2.5A

Have any TPS61178 design calculate tools?

  • 0
    TI__Genius 14385 points

    Hi,

    Sorry we do not have TPS61178 design calculate tools.

    The device is ok for this working condition.

    But it seems a better choice with TPS61022.

    Could you share more about the application?

    Best Regards,

    Fergus

  • 0 in reply to Fergus He
    Prodigy 20 points

    I attach files on the attachment.

    The conditions I use dynamic electronic load are: 0.75A~2.5A, 10ms, 2.5A/us.

    I hope to reduce the output voltage ripple by 5V +/- 5% when doing Transient Test.

    Please tell me how can I improve it?

    2.7V-4.2V to 5V.pdf

  • +1 in reply to user5248878
    TI__Genius 14385 points

    Hi,

    The Webench has output capacitors with 3X22uF/10V 1206, the efficitive is about 30uF totally.

    In schematic is 2X22uF/6.3V 0603, which is only 13uF totally.

    As a result, in webench design, the cross frequency is about 3k and in schematic it is much higher like 10k;

    it is hard to increase the cross frequency as it is quite high and easily to be unstable.

    It will be better to improve the output capacitance and increase the Rcomp at meantime that we can improve the load response.

    Best Regards,

    Fergus

  • 0 in reply to Fergus He
    Prodigy 20 points

    I added 3 22uF/10V (0805), and modified Rcomp = 24k, and the transient 5V waveform was less than +/-5%.
    In this case, how should I calculate loop compensation Cc, Rc value?

  • 0 in reply to user5248878
    TI__Genius 14385 points

    Please use the formular to estimate the transient.

    The Cout and fbw directly influence the transient response.

    Also, the stage loop gain and compensation loop can be gained by(refer to the datasheet):

    then you can see find the fbw accordingly.

    Best Regards,

    Fergus