TPS51518 – About Design Tool_1.0

Hide

Guru 21045 points

[Q1]

Which parameter should I input into ΔIo_set?

[Q2]

I use ceramic capacitor 88uF(22uF x 4).

Should I input 88 into Co_ceramic?*

*Vp-p becomes [#DIV/0!] when I do not input Co_Bulk,

but Co_bulk does not input because I do not use it.

・Vin=12 or 19V

・Vout=1.85V / 1.045V / 0.995V / 0.945V

・Iout=6A(max)

・L=2.2uF

・Co=88uF (ceramic capacitor only 22uF x 4)

・D-CAP2 mode

0245.TPS51518 Design Tool_1.0(1).xls

over 12 years ago

0 Nancy Zhang over 12 years ago

TI__Mastermind 49450 points

Hi Hideto,

Please contact Osial Ou directly. He will support this part. His email address: osial-ou@ti.com

Thanks,

Nancy

0 JohnTucker over 12 years ago

TI__Guru**** 191445 points

Q1: If you are referring to cell D24, that is the allowable inductor ripple current as a percentage of the max Io current of cell C24. That is a user input. How much ac ripple current do you want? The general guideline for dc/dc converters is 20 to 40 %.

Q2: The equations are hidden, so I cannot see exactly what is going on. But it is obvious that the spreadsheet is set up for both bulk and ceramic outputs. I would recommend putting 2 x 22 uF as "bulk" and 2 x 22 uF as "ceramic" (note I think there is a typo in cell F68, it should read Co_Ceramic_No.). DCAP2 mode should support ceramic output caps only.

0 Hide over 12 years ago in reply to JohnTucker

Guru 21045 points

Hi John,

Thank you for your prompt reply.

I have one more question.

Is the value of L and C appropriate?

This value meet Equation17 of the data sheet P26.

Flc=1/2√(Lout * Cout) < 1/10 * fo = 9k ⇔ 12kHz

< Parameter>

Lout=2.2uH

Cout=88uF (22uF x 4)

< resultant value>

Flc=11.4kHz

0 JohnTucker over 12 years ago in reply to Hide

TI__Guru**** 191445 points

I'll take a look at it later today...

0 Nancy Zhang over 12 years ago in reply to JohnTucker

TI__Mastermind 49450 points

Hi Hideto,

Please contact Osial Ou in China (osial-ou@ti.com ) directly. He is system engineer for this part and will give you the support.

Thanks,

Nancy

0 Hide over 12 years ago in reply to Nancy Zhang

Guru 21045 points

Hi Nancy,

Thank you for your advice.
I contact him.

Power management

Power management forum

TPS51518 – About Design Tool_1.0