I have selected the battery charger IC as LT1513 and boost regulator IC as LT3581.

These are the links for the datasheets.



These are my calculations for battery charger and boost converter (find attachment)

The first two calculations are for battery charger.

Battery voltage is 3.6V and I chose Vbat as 4.2V because for each Ni-CD cell I read that the max charging voltage should not exceed 1.5V and so it will be 1.5V * 3 = 4.5V.

So, I chose 4.2V.

Just give me a confirmation whether my R1 value calculation is okay or not ?

For boost converter please check the calculations in the attached PDF.
Refer page no 13 of datasheet (LT3581), Boost Design Equations.

I require max 1.2A from the boost converter.

I am having problem in Step 7 of Boost Design Equations (page 13 of datasheet).
I will not be using PMOS and I want to know how to calculate Cout = Cout1 + cout2.
Should i just remove the Rdson_pmos from the equation of step 7 or replace it with 1 ?
Also I have issue with step 10 of the equations that is for Rt. In attached pdf I am getting negative value for Rt that is