I am trying to modify or create a circuit that would control boosting of voltage over time so that it would start at the regular voltage, not boosted, and end up at maximum boost, or some predefined value.

I currently have a boost converter that is controlled by a potentiometer, which is the usual design seen online, however, I'd like to get a digital control of the boost over time, to make the gain smooth and over long periods of time.

Initial thought was, of course, to use a digital potentiometer, because that's the natural digital replacement for potentiometer, as the name tells.

However after a couple of searches regarding digital potentiometers, it seems that they're used for much lower voltages, and I am trying to boost from 24v to about 32v, which is way out of range for most digital potentiometers.

However there is available also those rated for higher voltage, but the amp limitation is still pretty low, I myself don't fully understand the working principle of a boost converter, so am not sure whether the current draw from the output of the boost converter relates to the current going through the digital potentiometer.

The main problem to solve is to get a gradual increase from 24v to 32v controller digitally, by Arduino for example, and the question is whether or not the digital potentiometer is a viable solution, what is if there is a better solution for the given problem? and is the current limitation of the digital potentiometer related to the current passing through the boost converter?

  • \$\begingroup\$ What's the purpose of the gradual increase? Can it be relatively uncontrolled in the sense that an open-loop voltage multiplier or switcher might produce (at some point the load itself will limit the final value)? \$\endgroup\$ – jonk May 4 '17 at 17:24

Forget about using a digital potmeter, it's too complex.

How a voltage regulator usally works is that it uses a fixed reference voltage and compares that to a fixed (for constant output voltage) or variable (variable output voltage) feedback voltage.

You're thinking about changing the feedback with a digital potmeter. That's complex to implement.

What is much easier is to use a fixed feedback voltage divider, for example 10:1 and compare that to a variable reference voltage.

You can make such a reference voltage by using the DAC. Or when using a micro controller, one of the PWM outputs. You need to filter that PWM signal with some RC filter stages so that at the output of the filter you get a variable (and digitally controllable) voltage of for example 0 to 5 V.

The regulator feedback loop then multiplies that variable reference voltage by a factor 10: and presto 0 to 50 V output voltage range.

Have a look here which discusses a Chinese "B3603" digitally controlled DCDC converter which uses the principle I explained.

If you do not need the digital control you could also just use a sawtooth generator circuit to generate a 2 - 5 V sawtooth, then use that as the reference voltage for the regulator circuit to multiply that to 20 - 50 V for example.


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