Newbie here, I am working on a project with a panel of 12 - 15 LEDs(std 5mm through hole LEDs) in paralell. I am currently using a 5V 1A SMPS. I used 330 Ohm resistors for current limiting. It works great! (Schematic in first figure). 
I know using resistors for current limiting is not efficient, moreover I have no control over the brightness of the LEDs.
Now, I want to make upgrades to the panel:
- Use a driver IC to save power
- Use a POT to control intensity of LEDs1
- Do the above 2 points without a Micro controller or a timer IC (Tomake it as simple and cost effective as possible).
Is there any such driver IC(powered by a 5V 1A SMPS) that can take input resistance from a POT and drive 15 RED leds by controlling the intensity of brightness..