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Project Notes

#393 Dickson Charge Pump

Zener-regulated 12V Dickson Charge Pump driven with Arduino PWM.



The Dickson Charge Pump is a very neat trick for multiplying an input voltage.

It is basically a capacitor bucket-brigade, with diodes for flow control, and a switching signal to make it go.

It is not the most efficient voltage booster, and cannot drive very high currents, but may be a convenient solution depending on the application.

Switching Signal

I’m using Timer2 Fast PWM to generate a pair of square-waves on Arduino pins 3 and 11 (OCR2B, OCR2A) at 62kHz. The duty cycle is set at 50%, and the waves are an inverted pair by setting OC2A to clear on Compare Match and OC2B to set on Compare Match.

Here’s a scope trace of the two waveforms (CH2 is offset -6V for clarity).


Since we’re using the chip’s native PWM capabilities, it is not possible to change the pins that the PWM signals appear on.

Note: it is possible to use other pins by using one of the other timers. This sketch uses Timer2 as it is generally available and is not used by other standard libraries.

See LEAP#254 AvrHardwarePWM for more details on hardware PWM.

Zener Regulation

Without the zener diode in place, this 4-stage charge pump delivers about 16V at the output tap.

The 1N4742 has a nominal zener voltage of 12V. An (optional) 2.2kΩ resistor is in series to soak up some of the voltage drop.

I’ve included a 10kΩ resistor to simulate a load on the 12V supply.


Works great:

  • very little ripple, < 20mV
  • charge pump and load drawing under 2mA
  • Arduino, which is also powering the charge pump, is drawing around 20mA total


The DicksonChargePump.ino sketch is about as simple as it gets:

  • sets up PWM
  • in the main loop, demonstrates how to turn on and off the PWM outputs by changing the pin mode (5 seconds on, 5 seconds off)


The capacitors used here are monolithic ceramics, 220nF for the pump stages and 1µF for the final. The ones I have are rated for at least 25V.




Credits and References

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This page is a web-friendly rendering of my project notes shared in the LEAP GitHub repository.

LEAP is just my personal collection of projects. Two main themes have emerged in recent years, sometimes combined:

  • electronics - usually involving an Arduino or other microprocessor in one way or another. Some are full-blown projects, while many are trivial breadboard experiments, intended to learn and explore something interesting
  • scale modelling - I caught the bug after deciding to build a Harrier during covid to demonstrate an electronic jet engine simulation. Let the fun begin..
To be honest, I haven't quite figured out if these two interests belong in the same GitHub repo or not. But for now - they are all here!

Projects are often inspired by things found wild on the net, or ideas from the many great electronics and scale modelling podcasts and YouTube channels. Feel free to borrow liberally, and if you spot any issues do let me know (or send a PR!). See the individual projects for credits where due.