I want to light up 8 LEDs where I should be able to control intensities of the LEDs as well. Since I want the circuit to be as small as possible on a printed circuit board (PCB,) I am using an Attiny85 IC for the following problem.
For all the 8 LEDs, I would like to light them up with a very good brightness level. So say, current of each LED is 20mA.
The Attiny85, has two PWM pins (PB0 and PB1)(i.e., pin 5 and pin 6.) But since the maximum output of each pin on the Attiny85 (or Arduino Uno) is 40mA, if I connect 3 LEDs to a single Attiny85 pin, the current will be divided and the intensity of LED is lower.
I am planning to use a 74HC595 shift register IC so that I can connect the PWM pins of micro controller as the input to 74HC595 IC and control 8 LEDs with the 8 output pins of 74HC595 without any current dividing factor.
Is this a good idea, or will the low current (low intensity of LED) issue on each output pin of 74H5C95 still exist since we are using only 3 pins of the Attiny85 to control all the LEDs with a 74HC595 IC?
Basically, I want to know how much current output will be getting from each pin of 74HC595.
Any other thoughts would be very helpful.