DC to DC Converter: Circuit, Working & Applications
Table of Contents
What is a DC to DC Converter
The DC to DC Converter changes the DC voltage from one level to another. It is necessary to provide a voltage for each device because the operating voltage of various electronic components, like ICs and MOSFETs, can range over a wide range. In contrast to a Boost Converter, a Buck Converter produces an output voltage that is lower than the input voltage.
The circuit is efficiency, ripple, and load-transient response can all be modified by using DC-to-DC converters. The most effective external parts and components are typically reliant on operating circumstances like input and output requirements. As a result, when designing the products, the standard circuits must be modified or changed to meet each product’s unique specification needs. A great deal of knowledge and experience in that area are required to design a circuit that complies with the specification and all requirements.
When the battery voltage can be above or below the regulator output voltage, step-up or step-down DC-to-DC converters can be helpful. To maintain a constant load voltage throughout the operation over the entire battery voltage range, the DC to DC converter must be able to function as a step up or down voltage supplier.
Working Principle of DC to DC converter
The DC-to-DC converter operates on a very straightforward principle. Unexpected changes in the input current are caused by the inductor in the input resistance. The inductor receives energy from the input and stores it as magnetic energy if the switch is kept as high (on). The energy is released if the switch is kept as low as possible (off). Here, it is assumed that the capacitor’s output will be high enough to support the time constant of an RC circuit on the output side. It is ensured that the steady-state output voltage is constant by comparing the enormous time constant to the switching period. It must exist at the load terminal and be Vo(t) = Vo(constant).
Types of DC to DC Converter
Energy is periodically stored and released from a magnetic field in an inductor or a transformer in these DC-to-DC Converters. The range of frequency is 300 kHz to 10 MHz. The amount of power that must be transferred continuously to a load can be more easily controlled by maintaining the duty cycle of the charging voltage. Additionally, the control can be used to regulate the input current, output current, or to keep the circuit is power level constant. The isolation between the input and output can easily be provided by the transformer-based converter.
Non-isolated converters are typically used when the voltage change is minimal. It has output and input terminals that connect to a common ground. The main drawbacks are that it cannot protect against high electrical voltages and that it generates more noise.
The output voltage VOUT of a typical non-isolated step-down or buck converter is determined by the input voltage VIN and switching duty cycle D of the power switch.
The same number of passive components are used, but they are arranged to step up the input voltage so that the output is greater than the input. It is used to boost the DC to DC converter voltage.
Depending on the duty cycle, this converter enables stepping up or down of the input DC voltage.
The output voltage is given by the relation as mentioned below:
|1||VOUT = -VIN *D/ (1-D)|
The polarity of the output voltage in relation to the input is always reversed, as can be seen from the expression above. Consequently, a voltage inverter is another name for a buck-boost converter.
The input and output terminals of the isolated converter are isolated from one another. They possess high voltage isolation characteristics. They are able to filter out interference and noise. And They are able to generate a cleaner and desired DC output voltage as a result. They are divided into two additional categories.
I: Flyback converters
This converter functions similarly to the non-isolating category’s buck-boost converter. The only distinction is that a transformer rather than an inductor is used to store energy in the circuit.
II: Forward Converters
The transformer is used in this converter’s operation to send energy from the input to the output all at once.
Advantages of DC to DC Converters
- It provides isolation in the primary and secondary circuits from each other.
- It simplifies the power supply systems in the circuit.
- So It is available as a hybrid circuit with all elements in a single chip.
- So It provides a technique to extend potential (voltage) as required.
- The output is well organized as positive or negative.
- It is also used in the regulation and control of DC voltage.
- Battery space can be reduced by using a converter.
Disadvantages of DC to DC Converters
- Switching converters lead to more noise.
- More ripple current, More input and output capacitance, higher losses, etc.
- So They are expensive as an external circuit is required.
- Choppers are inadequate due to unsteady voltage and current supply.