Varying duty cycle controls average power to motors and LEDs.
PWM varies duty cycle at fixed frequency to control average power: V_avg=D·V_max. Used for motor speed, LED dimming, servos (1–2 ms pulses at 50 Hz) and class-D audio. Frequency must exceed what the load can respond to.
25% duty at 12 V gives 3 V average.
PWM controls average power by varying the duty cycle, which is how most embedded systems dim LEDs and drive motors efficiently.
Varying duty cycle controls average power to motors and LEDs.
PWM controls average power by varying the duty cycle, which is how most embedded systems dim LEDs and drive motors efficiently.
The fraction of each period that the output is high, and the average voltage is the supply times this fraction for a simple switch.
The switch is fully on or fully off, so it dissipates little power, unlike a linear control that drops the excess voltage as heat.
Typical applications include dimming a lighting panel with a 10 kHz PWM signal, controlling the speed of a DC fan with a MOSFET and driving a servo with a pulse of about 1 to 2 milliseconds.
Study "Timers and counters" first (topic 62 of 104 in Electronics & Embedded). It covers the groundwork this topic builds on.
Duty cycle resolution. Dead time in half bridges. Filter to get an analogue level.
25% duty at 12 V gives 3 V average.
The next topic is "UART", which builds directly on this one.
It is classed as Intermediate in Electronics & Embedded (topic 63 of 104). It is an intermediate topic. Work through the beginner topics in Electronics & Embedded first.
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