LM5118 design spreadsheet question

Brian Wang

Other Parts Discussed in Thread: LM5118, LM5117

Hi,

I am using the LM5118 Quick Start Component Calculator to design for 16V - 32V input, 30V @ 5A output. The output will ramp between 1.23V and 30V and I wanted to see what the calculated values were down to 1.23V output. However with output below 11V, it is no longer in buck-boost mode operation and the calculator doesn't give values for peak inductor current, current sense resistor, and error amplifier compensation. I understand the LM5118 will start operating in buck mode but why does the calculator not calculate those values in this range?

0654.LM5118_Calculator 1040 heater 150W.xls

Thanks in advance for the help.

Regards,

Brian Wang

over 12 years ago

0 Youhao Xi over 12 years ago

TI__Guru* 78070 points

Hi Brian,

The spreadsheet was intended for application including buck-boost mode. In your 1.23V output, it is always the buck mode and the spreadsheet is no longer suitable. You may borrow the LM5117 quick start calculator, and do the calculation for pure buck mode, if you don't want to do it yourself manually.

Thanks,

Youhao Xi, Applications Engineering, TI SVA-PPD

0 Brian Wang over 12 years ago in reply to Youhao Xi

TI__Expert 8485 points

Thanks for the prompt response Youhao!

Regards,

Brian Wang

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LM5118 design spreadsheet question