TPS61178: How to set up Switching Frequency

Ryoma Miyazawa

Prodigy 95 points

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 "C_FREQ" derived in the above figure?

(C_FREQ is for pattern capacity?)

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

Regards,

Ryoma Miyazawa

5 months ago

0 Fergus He 5 months ago

TI__Genius 14385 points

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

0 Ryoma Miyazawa 5 months ago in reply to Fergus He

Prodigy 95 points

Hi Fergus,

Thank you for your prompt reply.

I missed the block diagram.

I understand about parameter "C_FREQ".

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

I apologize that my comprehension is lacking.

Regards,

Ryoma

+1 Fergus He 5 months ago in reply to Ryoma Miyazawa

TI__Genius 14385 points

Hi Ryoma,

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

Best Regards,

Fergus

0 Ryoma Miyazawa 5 months ago in reply to Fergus He

Prodigy 95 points

Hi Fergus,

I understand about parameter "k".

Thank you so much for your help.

Regards,

Ryoma

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TPS61178: How to set up Switching Frequency