If you want discrete analog control over one output at a time, you can use a multiplexer. For digital control over multiple pins, you could use an addressable latch or a shift register. If you need pseudo-analog control over multiple pins, you could use a PWM driver. There are also several LED driver chips that are designed specifically to control groups of LEDS.
So the ST16C596 shift register is similar to the popular 74HC595 shift register, but it’s nicer becaus
e it can sink a constant current to the LEDs it’s driving.
