"AFICR, Vdo = 1.3V" Do you know what AFCIR means?

No I don't know sir.

 

PD = ((VIN − VOUT) × IL) + (VIN × IG)
in my case. vin = 7.4v vout = vf of led (3V)
IL= 400mA. what is IG?
I want to check if I need to use heatsink.

The current out of the Adj pin Ig is so small, ignore it. The dissipation in the LM117 is (Vin-Vout) * Iled. Dont forget that V0ut = Vf+1.25V

The dissipation in the current limiting resistor is 1.25*Iled (Dont forget it).

 

No I don't know sir.

As Far I can Remember.

See, I should have looked at the data sheet, too.