TPS62060 inductor selection

Q:  

My customer is trying to optimize the inductor in his TPS62060 application. The inductor recommended is too big.

Application spec: Vin 3.135V to 3.465V, Vout=3.0V, Iout = 400mA.

 

As per equation 2, if I use a 1uH inductor, IL comes to 475mA around? Can I use PLF1610-102ME inductor from Coilcraft which has Isat of 1000mA at 20% drop?  Otherwise, what Inductors do you recommend?

 

Can you please send me an efficiency curve for my specific application?

 

Do you have any simulation file which I can use to see ripple, efficiency etc for different inductors?

 
A:

With that inductor and your Vin range, you will be in dropout at 400 mA load and 3.135Vin based on the equation on page 13 of the datasheet.  i.e. your Vout will be less than 3V because of the drops across the inductor and high side FET.  Your might look at an LDO for a Vin range that is so close to Vout.  Such a solution would definitely be smaller, though slightly less efficient at some operating points.

Yes, that inductor is ok to use.  It has a saturation current higher than the result of equation 2.  It is the smallest one I could find, when I did a quick search.

This application note can help you calculate the efficiency with your new inductor: http://focus.ti.com/lit/an/slva390/slva390.pdf  We have a spice model for the TPS62060/5/7 that may help.