The main reason LEDs need resistors is to protect the LED from excessive current which can permanently damage the LED. LEDs have current ratings which indicate the optimal current at which the LED operates effectively.
Why would you drive an LED without a resistor? Simple, to make your circuit more energy efficient. Should you drive your LED with PWM set to a constant duty cycle (i.e. 5V PWM at 34% duty cycle to achieve an average voltage of 1.7V)? Yes and no.
7qIS2Fz.
  • 4ah3j37dr2.pages.dev/156
  • 4ah3j37dr2.pages.dev/489
  • 4ah3j37dr2.pages.dev/5
  • 4ah3j37dr2.pages.dev/281
  • 4ah3j37dr2.pages.dev/258
  • 4ah3j37dr2.pages.dev/370
  • 4ah3j37dr2.pages.dev/164
  • 4ah3j37dr2.pages.dev/68

    • why do leds need resistors