This thread has been locked.

If you have a related question, please click the "Ask a related question" button in the top right corner. The newly created question will be automatically linked to this question.

TPS61178: How to set up Switching Frequency

Part Number: TPS61178

Tool/software:

Hello expert, 

Please let me confirm how to set Switching Frequency for TPS61178.

※The data sheet contains the following description:

How are "k" and "CFREQ" derived in the above figure?

(CFREQ is for pattern capacity?)

I could not find a description of those parameters in the datasheet.

Regards, 

Ryoma Miyazawa

  • Hi Ryoma,

    The parameters are inside the device.

    Please see device Functional Block Diagram below.

    The device uses external Rfreq to change the charging current of the capacitor, 

    when the voltage reaches a typical value, it triggers the comparator and generates the Clock.

    Cfreq is the inner charging capacitance, and Tdelay is the delay time of the Comparator.

    Best Regards,

    Fergus

  • Hi Fergus, 

    Thank you for your prompt reply.

    I missed the block diagram.

    I understand about parameter "CFREQ".

    On the other hand, is the parameter “k” always k=3?

    I apologize that my comprehension is lacking.

    Regards,

    Ryoma

  • Hi Ryoma, 

    Yes, the K is always 3 for the frequency calculation formular.

    Best Regards,

    Fergus

  • Hi Fergus, 

    I understand about parameter "k".

    Thank you so much for your help.

    Regards,

    Ryoma