TIOS1013: Current limit equation and accuracy

Nam, Dino

Expert 6325 points

Part Number: TIOS1013

Dear team,

I found current limit equation is like below on other E2E thread. is it correct equation?

I_threshold = (350 mA) * (20 kOhm / (R_set + 20 kOhm))

If Rset is 100Kohm, the calculation value is 58.3mA. Is it correct?

How about accuracy?

At datasheet like below, the current limit range is very wide. How can I know Min/Max limit value If I use other Rset value using above equation?

Is there any specification Min/Max % value?

Thank you.

over 3 years ago

+1 Danny Bacic over 3 years ago

TI__Mastermind 26736 points

Dino,

This equation is a good way to calculate (up to 100 kΩ at least). Could you link the E2E post you referenced here for future readers?

You are also welcome to use Figure 6.4 to help you visualize the current limit as a function of R_SET.

Regarding min/max, this varies with slightly increasing % from 0 kΩ to 100 kΩ. At low R_SET you can estimate a min/max variation around 15% but it will increase as R_SET increases, particularly as it passes approximately 75 kΩ, at which point the min/max current limit approaches the value you highlighted in the data sheet.

Best,

Danny

0 Nam, Dino over 3 years ago in reply to Danny Bacic

TI__Expert 6325 points

Hi Danny,

Thank you for your comment.

Do you mean below Rset 75 Kohm, Min/Max value of current limit is about +-15% but above 75Kohm Rset, Min is 30%, Max is 40%?

The variation using 100Kohm Rset will be the Maximum value. Is it right?

E2E post link I referenced is below.

https://e2e.ti.com/support/interface-group/interface/f/interface-forum/733881/tios101-more-information-on-rset-for-current-limiting?tisearch=e2e-sitesearch&keymatch=TIOS101#

Thank you.

+1 Danny Bacic over 3 years ago in reply to Nam, Dino

TI__Mastermind 26736 points

Dino,

Yes, I believe you understand correctly. Tolerance (i.e. max/min %) increases as R_SET value increases, as you noted.

The 100 kΩ R_SET value will have the max/min as defined in the table you included in your original post above.

Thank you for including the link!

Best,

Danny

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TIOS1013: Current limit equation and accuracy