# Is there any module that controls power supply with variable voltage by PWM input? [closed]

I am stuck for a few days already at finding a solution for controlling a motor. We can easily find a motor or LED on the market. However, those modules for motors do not have a built-in regulator as inductors can smooth out the voltage itself.

What I want is a variable power supply module with a voltage regulation function, whose output voltage (e.g. 5V to 12V) can be controlled via PWM . Does such a thing exist in the market?

UPDATE 1

I would like to use Arduino/Raspberry to control PWM signal.

As I am looking for a general solution that can be used for different Loads, I don't know the spec of the Loads, let say they are ranging from 5V to 12V and max rated current would not be >2A. You may take CNC Laser module as example

• You do use RC low pass filter, then you need an analog input. There is no such thing to accept PWM input. PWM is a method to generate an arbitrary voltage amplitude by means of switching the DC supply voltage. Commented Apr 20, 2020 at 7:40
• Then is there any simpliest way to achieve it? If I have different Loads with different rated voltage in my circuit, I should prepare multiple power sources in order to supply different voltage? Commented Apr 20, 2020 at 8:00
• Then, your question becomes not clear enough, you should edit. What loads? What you want to control with this PWM signal? Where the PWM comes from? Commented Apr 20, 2020 at 8:06
• @MarkoBuršič, I have updated the question. Let see if it is enough? Commented Apr 20, 2020 at 8:47
• Using a PWM signal to control the output voltage is a must, or you just want to have a controlled output voltage? Commented Apr 20, 2020 at 10:23

## 2 Answers

You can use any regulator available in the market with external feedback divider for that. You can manipulate the resistor divider to change the output voltage of the regulator. I see two options:

1. You can switch in/out series resistors configured with powers of 2 sizes. This way you can achieve 2^N different output voltages just by switching in/out resistors in the feedback divider. You can use general purpose MOSFETs to switch the resistors in/out. You will need N digital outputs from your microcontroller for that, so it is not exactly what you are asking.
2. You can average the PWM signal by using an RC first order low pass filter. Then, you can create a voltage controlled current source. The accuracy you are looking for determines what topology to use for this current source. If you need accuracy, then you will need an op amp circuit. If accuracy is not critical, then you can get away probably with a simple emitter follower. Then you sink this current from the feedback node of the resistor divider. The more current you sink, the higher will be the output voltage.

If you really want to drive it with a PWM signal, instead of regulating a power supply why don't you use a fixed power supply with a PWM driver. For example, the DRV8874 from TI is capable of delivering up to 6A and the voltage can range from 4.5 to 37V. Below is the reference design and how you would connect it to you PWM source. Furthermore, it provides a couple of safety features which can come handy.