A Buck Converters helps step-up, step-down or invert a given voltage level. For instance, a DC-DC converter that changes 12 volt to 1.5, 4.5, 7.5 or 9 volt is useful in automotive applications; those that step up 2 volt to 15, 18 or 20 volt are used in charging laptops from automobile power points.
Power Supply Converter (DC/DC): Basic Types
Although there are different types of converters, the two basic types of DC/DC converter are:
1. Isolated: These converters are characterized by the presence of an electrical barrier between the input and output. The barrier is provided by a high frequency transformer, which can withstand a few hundred volts to several thousand volts. The output of an isolated converter can be positive or negative and are useful in medical applications. These devices are available in different types and configurations. The two basic types are flyback and forward. Both these use the energy stored in the inductor’s magnetic field for their operation.
1.Flyback: In this type of power supply converter, a transformer is used to store energy, rather than a single inductor. It has two discrete phases for energy storage and output delivery. The magnetic flux of the transformer core never reverses in polarity; hence, to avoid the resultant magnetic saturation, the core must be large enough for the given power level. These are used in lower power applications, such as cathode ray tubes and Geiger counter tubes, which draw lesser current.
2.Forward: The transformer transfers the energy between the input and the output in a single step. This power supply converter can step-up or step-down voltage or offer a combination of the two. For multiple outputs, all one needs to do is manipulate the turns on the secondary winding. Applications include car amplifiers, where low battery voltage is stepped up to obtain higher output for the amplifiers.
2. Non-isolated: Also called Point of Load converters, these step up or step down voltage by a low ratio. These have ICs specifically meant for the purpose, and a DC path between its output and input. The five main types of non isolated converters are: Buck, Boost, Buck-Boost, Cuk and Charge Pump. While the Buck steps down the voltage, Boost steps it up. Buck-Boost and Cuk are able to step up as well as step down the voltage.