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TPS62665: Output capacitance allowed to achieve stability

Kean Leng Koay
Prodigy 20 points
Part Number: TPS62665
Other Parts Discussed in Thread: TPS62660,

Hello, 

From the datasheet, it is mentioned that the converter is optimized to operate with 0.3uH - 1.3uH inductor and 4.7uF - 10uF output capacitors.

Would like to know if there is a max allowable output capacitance for the controller to achieve stability or if there's any requirement on the output capacitance with this controller? Reason being is that the effective output capacitance on my board is about 47uF. There is a 4.7uF and 10uF near the controller side while the rest of the different combination of capacitors are scattered around the load side. The inductor used is 1uH in this case. I understand that this can be verified on the board by looking at the jitter, oscillation, transient response and etc, but it would be good if I can have a rough idea in designing phase whether if it is affecting the current design. 

Besides, looks like TPS62665/TPS62660 is not available in TI Webench and library in PSpice for TI. Thus, I couldn't do a simulation to confirm whether my design is fine. Is it possible if these parts can be added into any of the simulators above?

Appreciate your support in advanced. Thanks.

Regards, 
Kean Leng

  • +1
    TI__Mastermind 31321 points

    Hello Kean,

    Thank you for coming to us with your queries.

    The maximum Cout was not covered during the development stage of the device because the main objective was to have a converter with the smallest solution size. In assessing the control loop stability with Cout > 10uF, it is best to conduct a bode plot measurement or transient load testing and observe the output voltage behavior.

    Unfortunately, there is no plan to create a Webench or Pspice model for this part because it is already a 12-year-old device. Alternatively, we are encouraging customers to move to newer ICs that can be more price competitive.

    Can you like to consider the TPS6280x part? It has a 1A and 600mA output current version in the same package. Webench and Pspice are available for this device as well.

    Best regards,

    Excel

  • 0 in reply to Excel Regidor
    Prodigy 20 points

    Hi Excel, 

    Thanks for the answers. 

    Regards, 
    Kean Leng

  • 0 in reply to Kean Leng Koay
    Prodigy 20 points

    Hi Excel, 

    Since these parts are 12-year old parts, does TI has any plan to make it into EOL in the coming future? Thanks.

    Regards, 
    Kean Leng

  • +1 in reply to Kean Leng Koay
    TI__Mastermind 31321 points

    Hi Kean,

    As of now, there is no immediate plan to EOL the part because there are still customers using it. For a future-proof design, you might like to consider our latest product. Does your application have any special requirements, such switching frequency range, etc.?

    Best regards,

    Excel 

  • 0
    Prodigy 20 points

    Hi Excel, 

    Thanks for the explanations and suggestions. 

    Regards, 
    Kean Leng