PWM SIGNAL FUNDAMENTALS FOR BEGINNERS

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fundamentals of pwm signal

Description of PWM

Pulse-width modulation (PWM signal) dimming is a common method for controlling the intensity of an LED source or sources. LED brightness (lumen output) is determined by the average forward LED current. The relationship
between forward current and lumen output is effectively linear at lower forward current levels, and becomes
nonlinear as forward current increases. Source efficacy (lumens per watt) begins to decrease in the nonlinear
segment of the range, because an increasing percentage of output power is converted to heat.
Pulse-width modulation (pwm signal) controls the timeaveraged current through an LED, and therefore, the brightness of the LED source or sources. In the pwm signal method, LED current level is set and then turned on and off very quickly, typically faster than is perceptible by the human eye. The dimming of the LED is proportional to the duty cycle of the pwm signal waveform.

Typical Use of Signal!

Pulse-width modulation (pwm signal) dimming is commonly used for both static and dynamic dimming. It is also used with white light sources and for light sources designed for color mixing, such as RGB sources, where the brightness of the individual colors are adjusted to deliver the desired color.

Pulse Width Modulation (PWM Signal) for LED Dimming?

Pulse-width modulation (PWM signal) dimming is a common method for controlling the intensity of an LED source or sources. LED brightness (lumen output) is determined by the average forward LED current. The relationship
between forward current and lumen output is effectively linear at lower forward current levels, and becomes
nonlinear as forward current increases. Source efficacy (lumens per watt) begins to decrease in the nonlinear
segment of the range, because an increasing percentage of output power is converted to heat.Pulse-width modulation (pwm signal) controls the timeaveraged current through an LED, and therefore, the brightness of the LED source or sources. In the pwm signal method, LED current level is set and then turned on and off very quickly, typically faster than is perceptible by the human eye. The dimming of the LED is proportional to the duty cycle of the pwm signal waveform.Pulse-width modulation (pwm signal) dimming is commonly used for both static and dynamic dimming. It is also used with white light sources and for light sources designed for color mixing, such as RGB sources,
where the brightness of the individual colors are adjusted to deliver the desired color.

Pulse-width modulation (pwm signal) dimming is a common method for controlling the brightness of an LED. The LED current level is set and then turned on and off faster than is perceptible by the human eye. The dimming of the LED is approximately proportional to the amount of on time to the amount of off time; for example, the more time the current is on, the brighter the LED appears to be. The European market has a pwm signal protocol for the dimming of fluorescent lamps using a pwm signal dimmable ballast. The control signal is inverse to the dimming, for example, the more time the voltage is on, the dimmer the lamp, and the lesser the time the voltage is on, the brighter the lamp. This dimming protocol is defined in IEC 60929 Annex E.3.

A few smart informations need to know about PWM Signal

Because it keeps forward current constant, pwm signal dimming is often preferred over analog dimming methods for LEDs, since it prevents color-shifting (changes in dominant wavelength) that occur with changes in drive current. Such changes are especially noticeable in white-light LED applications, where even small shifts in the CCT of adjacent LED nodes may be readily perceptible.

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