Ideal ripple current on a DC to DC step down switching regulator

I was studing a linear's datasheet, a step down DC to DC switching regulator.

More specific: the LTC3615.

I am a little bit confused with ripple curent which involved to inductor value calculation. In the datasheet, PAGE 25, "Design Example" a ripple current considered 1A.

And here is my problem. In my research on google i found plenty information about this and all of them refer the ripple current, for properly application, a value of 10 - 30% of maximum DC Load current on the Output. And in the datasheet, Linear choosing that value 1A, for 3A maximum output. 1/3 of maximum current.

Is there some information that i haven't notice?

• Ripple current can be much bigger than load current so please provide links to what you read. Sep 19, 2015 at 23:13
• electronics.stackexchange.com/questions/49280/… Sep 19, 2015 at 23:36
• cooperindustries.com/content/dam/public/bussmann/Electronics/… Sep 19, 2015 at 23:39
• I think the value of the ripple current is one of the initial design choices ! So saying that the ripple current should typically be 10 - 30% of the DC load current can only be true for a limited set of cases. For example when the load current does not very a lot (for example: 0 A (off) or 1 A). But when the load current does vary a lot (for example, 0 A, 1mA, 100 mA or 1 A) and for all these currents you want a decent efficiency then a different choice for the ripply current (under full load) might be more advantageous. Sep 20, 2015 at 11:32
• I think that for the 1A output you can choose a 1A ripple current as the maximum current will always be below the maximum current the switch can handle. In te same way 3A DC + 1A ripple might just be OK but 3A DC + 3 A ripple will be too high for the switch so the ripple must be reduced to 1A. Sep 20, 2015 at 11:40