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LM61460-Q1: Questions on efficiency (assumptions made on eff vs freq plot on page 1) and how to select Cout, CFF and RFF with a Vout of 12V

Craig Dekker
Intellectual 350 points
Part Number: LM61460-Q1

E2E,

1.  What losses does the efficiency vs frequency figure on page 1 of the spec?

I was wondering if the figure assumes only conduction and switching losses (no inductor losses) or conduction, switching and some standard/typical DC and HF inductor losses.

2.  The spec recommends a good number of parts when Vout = 3.3 or 5V.

Does TI recommend parts/sizes for Cout, CFF and RFF when Vout = 12V?

I can size Cout based on standard buck Cout equations though I do not know how to size CFF and RFF to optimize the system's loop gain (fc, phase margin).

A corresponding"quickstart" guide would be nice.

Power designer does not offer any help and limits the output to 4A when the spec states 6A.

Thank you,

Craig

  • +1
    TI__Guru 50120 points

    Hello Craig, 

    1. The front page of the datasheet shows efficiency versus load current. The efficiency is taking by measuring the output voltage and output current after the inductor so these losses should be accounted for in the overall efficiency measurement.

    2. Please use the Webench designer tool located in the LM61460-Q1 product folder to simulate for different output voltages. 

    Regards,

    Jimmy