Background: I want to use this chip to combine the power output of two 2.4A USB ports on a USB power bank I have. If this is possible it will output ~25W and w/ my dc-dc converter I should be able to charge my laptop using USB power banks. If possible in the future I may buy 2 chips more to combine 4 USB outputs.

I presume I will be using a design very similar to the typical application on the first page of the datasheet, but with the values listed in the 5V example on page 14. I might need to adjust the resistor on the range pin depending on how close the Vout on the USB ports will be.

Question: page 11 of the datasheet, MOSFET selection, the last paragraph's phrasing confuses me. I can't tell if it wants me to get a Rds(on) value as close to what the equation gives, or if that is a maximum value for Rds(on) and anything below should suffice. The given equation is ΔVIN(SH) = VFR(MAX) – 0.5IL • RDS(ON),

VFR(MAX) is the maximum forward regulation voltage (Vin-OUT) Vin(sh) is the "sharing capture range"...not sure what that means what IL is has proven elusive as well... wish I knew what these all were

I could always use a very similar MOSFET to the SUM85N03-06P in the typical application, and ignore the equation altogether but avoiding errors would be cool, and who doesn't like to learn?

• Your DS LINK is wrong. – Andy aka Apr 26 '17 at 18:43

$\frac{I_L}{2}*Rds_{on} = V_{across mosfet}$