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What does this DCDC inductor "40%" mean?

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tony_lth

tony_lth

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HI,
When I read DCDC TPS61021ADS datasheet, I don't know the meaning of the following:
"... it is advisable to work with an inductor peak-to-peak current of less than 40% of the average inductor
current for maximum output current."
What does this 40% mean?
If the max peak current is 3.2A, then the inductor saturation current should be 3.2A/40%=8A?
Right?
Pls comment on this.
Best,
Tony Liu
 

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No, they mean that the peak current should not be more than 20% higher than the average current.
The saturation current is not involved in the statement, it should only be higher than the peak current.
 
Re: What does this DCDC inductor "40%" mean?

No, if the average is 3.2A then the peak-to-peak ripple should be 40% of 3.2A = 0.4*3.2A = 1.28A

Since peak ripple = 0.5*peak-to-peak ripple
Peak ripple = 0.5*1.28A = 0.64A
Peak current will then be average current + peak ripple
= 3.2 + 0.64 = 3.84A

- - - Updated - - -

The 40% means that the inductor current will swing about its average value by 20% on either side (+-20%).
 
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