TPS62097: about PFM/PWM switching point

Tsukui Yusuke

Guru 21930 points

Part Number: TPS62097
Other Parts Discussed in Thread: TPS62130, TPS62085

Hi,

Could you tell me about TPS62097 PFM/PWM swichig point.
Customers want to calculate the conditions to enter PFM.
Please your advice for the calculation formula.

Best Regards,
Yusuke/Japan Disty

over 8 years ago

0 Chris Glaser over 8 years ago

TI__Guru**** 151170 points

This is explained at the bottom of page 9. Equation 5 calculates the ripple current for any buck converter.

0 Tsukui Yusuke over 8 years ago in reply to Chris Glaser

Guru 21930 points

Chris-san,

Thank you for your support.
I confirmed the formula you taught me.
This expression is an expression for calculating the frequency of PFM.

Could you tell me more about the switch point of PFM / PWM?
Customer wants to know the current value at which the frequency begins to decrease.

Best Regards,
Yusuke/Japan Disty

0 Chris Glaser over 8 years ago in reply to Tsukui Yusuke

TI__Guru**** 151170 points

Yes, and this is later on in equation 5 (ripple current calculation). Page 9 explains that the PFM/PWM boundary is where the inductor current becomes discontinuous. This is at a load current of 1/2 of the ripple current.

0 Tsukui Yusuke over 8 years ago in reply to Chris Glaser

Guru 21930 points

Chris-san,

Thank you for your kind support.
Let me know one more thing.

・Is it correct with the understanding of the following calculation formula?
(Contents of the datasheet of the TPS62130.)

・Does this content also apply to TPS62085?

Best Regards,
Yusuke/Japan Disty

0 Chris Glaser over 8 years ago in reply to Tsukui Yusuke

TI__Guru**** 151170 points

Yes, this is correct.

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TPS62097: about PFM/PWM switching point