PWM

Electronic circuits can contain both analogue and digital components. PWM, which stands for Pulse Width Modulation, facilitates the control of analogue devices using a digital signal. Many electrical designs use PWM for regulation, with PWM used as a way to reduce the average power that is delivered by an electrical signal by chopping it up into smaller parts. RS offer a range of PWM Controllers from a multitude of trusted brands, including ON Semiconductor, STMicroelectronics, Texas Instruments, and more.

What do PWMs do?

Analogue signals can be on or off, or can even be put into a position half-way between the two, whereas a digital signal has just on or off positions. Both signals appear in electronic circuits and can often be required to work together. Inputs can be converted using a DAC (digital-to-analogue converter) or an ADC (analogue-to-digital converter). PWM is available to control the output of a device: for example, PWM can convert the digital output of a microcontroller (MCU) into an analogue signal to drive the next analogue component.

Types of PWM devices:

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 a duty cycle?

PWM signals feature two main things: frequency and a duty cycle. Duty cycle is given as a percentage (%) 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.