Driving 15 PWM LED's

Projects General Guidance
1

My second Arduino project and I need some guidance. I have a working program where based on the number of times you press a button the output of a PWM signal of some percentage of 3V. For instance one press is 3V, two presses is 2.5V, three presses is 2V, etc. Then when you reach 5 presses it resets and goes back to 0V.

For the hardware, I have 15 LED's that each consume ~9.5mA, total draw is 140mA. What would be the best way to drive these all together? Since the max output for a digital pin is 20mA and I don't want to have a bunch of wires, I was hoping to do this with one pin. This is for a nightlight for my daughter, and the 3V is too bright sometimes, so I'm using the button presses to dim it to her liking.

Thanks in advance.

2

Since you didn't post a schematic, I assume you have all the LEDs in parallel. I suggest looking at using a N-channel MOSFET to drive the LEDs. A PWM pin from the Arduino connects through a resistor to the gate of the MOSFET. You want a MOSFET that begins with IRLxxxx since those use 5 volts to bias the gate.