![]() LEDs are very nonlinear in their response to current, give an LED half its rated current and you still get more than half the light the LED can produce. Conversion into its analog equivalent value is straightforward. Many loads, such as resistors, integrate the power into a number matching the percentage. ![]() While the frequency is the same for each, this is not a requirement. Shown below are examples of a 10%, 50%, and 90% duty cycle. The ON time can be varied completely between signal being off to being fully on, 0% to 100%, and all ranges between. Most square waves are 50%, this is the norm when discussing them, but they don’t have to be symmetrical. One of the parameters of any square wave is duty cycle. PWM does not have to capture data, although there are exceptions to this with higher end controllers. PWM can have many of the characteristics of an analog control system, in that the digital signal can be free wheeling. If either voltage or current is near zero then power will be near zero. ![]() This is because power follows the following formula: Almost all the heat generated by a switching device is during the transition (which is done quickly), while the device is neither on nor off, but in between. ![]() Digital systems don’t generally generate as much heat. Pulse Width Modulation (PWM) uses digital signals to control power applications, as well as being fairly easy to convert back to analog with a minimum of hardware.Īnalog systems, such as linear power supplies, tend to generate a lot of heat since they are basically variable resistors carrying a lot of current. ![]()
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