- Jan 1, 1970
Well, no, you can have the LED produce any amount of light, between
none and its maximum, by varying the amount of current flowing through
it. Of course this requires dropping the rest of your supply voltage
across some other circuit element and so will use more power. But I
think the real reason that auto manufacturers use PWM is that
transistors for just on-off switching are cheap.
To join the chorus, I find them annoying also and really wish they
would use a higher frequency.
PWM is used in order to exceed the maximum continuous output available
from the LED. LEDs can be overdriven past their continuous operating
currents and generate higher peak light outputs (within some limits) by
operating them at a reduced duty cycle to hold the average current and
therefore chip heating within the continuous operating limits.