In the world of DC to DC convertors, the term “buck” refers to those devices which step down voltage and step up current between the input and the output. This makes it different from the boost converter which increases voltage, and from the buck-boost converter which can both increase and decrease it. In this article, we’ll be taking a look at its operating principle as well as some of its practical uses.


How does the Buck DC to DC Convertor Work?


  • To put it very simply, the converter can find itself in two states – either on or off, depending on the position of the switch.
  • When in the on-state, the current flows from the source to the load and charges up the inductor in the form of a coil in the process. The inductor gradually stores this energy as a magnetic field.
  • As a result of increased current, the inductor will try to resist those changes by producing an opposing voltage. This decreases the net voltage in the load.
  • Eventually, the rate of current change slows down and the coil will produce less opposing voltage – this increases the voltage in the load again.
  • Then the switch is opened (off-state), cutting the supply of current from the source and causing a voltage drop. The coil will try to keep the balance by inducing its own voltage and by converting the magnetic energy into current and pushing it further. This continues until the current is discharged or until the switch closes again and starts the new cycle.
  • By switching between the on and off states, the capacitor then produces the desired amount of more or less constant voltage.

That’s about the basic theory of this device. Theory is all great, but what about the practical uses? Well, they are plentiful and mentioning the following will merely scratch the surface…

The Buck Converters in Battery Chargers


Quick and efficient charging without overheating is the desire of all owners of portable electronic devices. The buck converters make this wish possible. For example, the mobile device is usually charged via a micro USB port which accepts 5V. The charging circuits usually contain a buck convertor which helps to regulate the voltage.

Have You Ever Attached a Flash Drive to Your Tablet or a Smartphone?


You probably have. The so-called USB On-The-Go is a ubiquitous technology. And if you were to analyse it, you would find a buck convertor to play an extremely important role in it. As the secondary device gets its power from the phone’s USB port, synchronous buck converters mediate this power flow.

The flow can be even bidirectional, with each device capable of taking the role of the host. More about USB On-The-Go here.


Solar Power Chargers Utilise This Technology a Great Deal as Well


Many products’s batteries are capable of being charged from higher voltage solar panels. Since the solar cells’ current and voltage curves are not linear, a buck converter is used to manage the power amounts, which it does by changing the load current. The converter itself is guided by a microcontroller which decides when and how to do it.


The Power for the Quadcopters and Drones


Quadcopters and drones are a popular tool with a variety of uses – but with no buck convertor, there probably wouldn’t be any. These machines typically use battery packs with range up to 25 V for power, but the actual voltage that the device uses is much lower – either 3.3 of 5 V. It’s up to the converter to step the voltage down.


Can you name some other instances in which the convertor is put to use? Mention them in the comments!

For more information please click on this link isolated dc to dc converter.