TPS4811-Q1: Clarification needed on datasheet discrepancy

Matt Calvo

Part Number: TPS4811-Q1
Other Parts Discussed in Thread: TPS1211-Q1

Tool/software:

Hey Power Switches Team,

I have a customer evaluating the TPS4811-Q1 (Specifically TPS48111-Q1) for a project and we ran into a discrepancy that we're hoping you can help to provide some clarity on. See details and questions below!

There seems to be two “Short-Circuit Protection” sections with conflicting formulas for R_ISCP: Sections 8.3.3 and 8.3.4. Do you know which is correct? Also, please note the incorrect PN highlighted in 8.3.3.

On another note, can the efuse cutoff FET drain and source be used for short-circuit/overcurrent protections like section 8.3.3 describes (instead of using a sense resistor)?

-Matt

over 1 year ago

0 Timothy Logan over 1 year ago

TI__Mastermind 34935 points

Matt,

I think one formula might have gotten there from the TPS1211-Q1 datasheet. The easiest way to calculate the values are to use the design calculator at:

https://www.ti.com/tool/download/SLURB09

That being said, looking at the calculator, the equation from 8.3.4 is correct. I will bring this to the attention of our systems team.

Best Regards,
Tim

0 Matt Calvo over 1 year ago in reply to Timothy Logan

TI__Genius 14755 points

Thanks for the reply Tim!

Can you also please help to comment on the other question in the post? I've pasted it below for reference:

On another note, can the efuse cutoff FET drain and source be used for short-circuit/overcurrent protections like section 8.3.3 describes (instead of using a sense resistor)?

-Matt

0 Timothy Logan over 1 year ago in reply to Matt Calvo

TI__Mastermind 34935 points

Matt,

It can- but keep in mind that the CS+ and CS- pins use differential sensing to detect the short-circuit event. By the time the voltage difference is big enough to trigger the short circuit event over the FET- it might exceed the rating of the FET.

Best Regards,
Tim

0 Matt Calvo over 1 year ago in reply to Timothy Logan

TI__Genius 14755 points

Hey Tim,

Makes sense, thanks for the additional info and advice!

I'll pass this along to the customer and will have them comment back on this thread directly if they have any follow-up questions!

-Matt

Power management

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TPS4811-Q1: Clarification needed on datasheet discrepancy