TPS54821: Error in data sheet, broken links to tools

Mikael Strom

Part Number: TPS54821
Other Parts Discussed in Thread: TPS54620,

Hi,

I'm looking for a tool to confirm my calculations, but the link to "TPS54620 & TPS54XXX Current-Mode Step-Down Converter Design Calculator (Rev. D) (ZIP 54 KB )" at www.ti.com/product/TPS54821/toolssoftware is dead.

In the data sheet "SLVSB14B –OCTOBER 2011–REVISED FEBRUARY 2016" the calculation for Vout in para 7.3.5 does not match the calculation in the example design (the example design use 10K/2.21K for 3.3V in the voltage divider, but the equation in para 7.3.5 gives 10K/45K which obviously is wrong). Further more, the text refers to the wrong resistors (it should state R7/R8 rather than R5/R6). The whole data sheet feels flaky and unreliable. Is there an updated data sheet which is correct?

Thanks,

Mike

over 7 years ago

0 Jason Wang (BSR-MV) over 7 years ago

TI__Genius 9550 points

hi,

I am looking into this question, and give you feedback on Monday.

0 Edwin Zang over 7 years ago

TI__Expert 6425 points

Hello Mike,

Thanks for your comments.

the calculation equation in para 7.3.5 should be below.

R7=(Vo-Vref)/Vref*R8.

According to the equation. if you set R8 as 2.21k ohm, R7 is 10k ohm. if you set R8 as 10k ohm, R7 is 45k ohm.

Actually, the equation is right, you maybe just mistake the up divider-resister and down divider-resister.

if you want to double check any other thing, you can send me email, edwin-zang@ti,com

best regards

edwin.

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TPS54821: Error in data sheet, broken links to tools