MPN

PWM

PWM stands for Pulse Width Modulation. Electronic circuits can contain both analogue and digital components. PWM allows you to control analogue devices using a digital signal. Many electrical designs use PWM for regulation.

Analogue signals can be on or off, but they can also be half-way on etc. Whereas a digital signal has just on or off positions. Both signals appear in electronic circuits and are required to work together. Inputs can be converted using a DAC or ADC. PWM is available to control the output of a device. For example, a PWM can convert the digital output of a microcontroller (MCU) into an analogue signal, to drive the next analogue component.

Types of PWM device:

  • PWM Voltage Mode Controllers work by applying a control voltage (Vc) and a PWM ramp (Vramp) input.
  • PWM Current Mode Controllers add a second loop feeding back to the inductor current to create the PWM ramp.
  • PWM Switching Regulators feed the input voltage back through the PWM controller to keep the output voltage constant.

What is duty cycle?

PWM signals feature two main things, frequency and a duty cycle. Duty cycle is given as a % and refers to the amount of time the signal is on. For example, if the duty cycle is 50%, the signal is on for 50% and off for 50% of the time period. Pulse width modulation uses a rectangular pulse wave.

Where is PWM used?

  • Motors
  • LED lighting
  • Lamps
  • Heaters/HVAC
  • Electric vehicles
  • Robotics
  • Communication systems

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