When using LEDs, some applications may require the user to dim and/or blink the light.  Dimming and blinking may be achieved by continuously switching the LED on and off. One way is to use an internal (on-chip) pulse width modulation (PWM) to switch the output on and off. A second method is to tie the output enable (OE) pin of the driving device to an external PWM. A third method is to continuously switch the supply voltage to the LED driving device on and off. The difference between dimming and blinking is dependent on the frequency at which the LED is being switched on and off.  For dimming, the LED must be switched on and off at a frequency faster than the human eye can detect. For blinking, the LED must be switched on and off at a frequency slower than the human eye can detect.