The dimmability of an LED bulb depends on the LED driver that the light uses.
All LED bulbs have a driver that converts the electricity into a low-voltage constant current that is needed for the LEDs to work. Confused on LED drivers? Check out our full LED driver guide.
If you are building your own setup with component LEDs then you have the luxury of choosing whichever LED driver you want, with the dimming options you desire. However, when buying a finished LED fixture / bulb you are limited to the dimming options that the manufacturer chose.
Non-dimmable LED drivers only know two states: ON & OFF. If you start to change the current to an LED bulb the non-dimmable driver will try to compensate and keep the current steady. This will eventually overwork the LED driver and it will fail.
Dimmable drivers, on the other hand, are made to handle drops in current. Dimmable drivers will compensate for the loss in current by dimming the LED with analog or pulse width modulation (PWM) dimming.
