What is a DC to DC Converter?

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Editorial Team - everything PE

Sep 12, 2021

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DC-to-DC converter is used to converts a DC input voltage level into different DC voltage levels at the output. There are two types of DC-DC Converters - 

Linear DC-DC Converter: It consists of a resistor load circuit that creates a voltage drop and regulates a linear DC output voltage. The converter is also called a series regulator because the circuit elements are arranged in series between the input and output. However, this type of converter is more theoretical and is not usually manufactured.

Switched DC-DC Converter: It stores the energy from the input DC voltage periodically and then releases that energy to the output at a different DC voltage level. The energy stored can either be magnetic (inductor or transformer) or electric energy (capacitor).

The DC/DC converters are ideal for applications such as trolley cars, battery-operated vehicles, DC drive, traction-motor control, machine tool industries, supplies for personal computers, and PLC systems, cell phone chargers, automobiles, telecommunications, and lighting.

Switched Mode DC/DC Converters are further classified into two configurations:

Isolated DC/DC Converter: In an isolated DC/DC converter, the input and output circuits are isolated utilizing a transformer. The transformer stores the energy and provides galvanic isolation between the input and output circuit. They use MOSFETs, SCRs, thyristors, and power transistors for switching. Key examples are flyback converter, forward converter, push-pull converter, bridge SMPS, isolated cuk, ringing choke converter, and resonant forward converter.

Non-Isolated DC/DC Converter: In a non-isolated DC/DC converter, the input and output circuits share a common ground configuration. An inductor or capacitor stores the energy from the input voltage source and regulates the output at different voltage levels. Key examples are step-down/buck converter, step-up/boost converter, buck-boost converter, cuk converter, split-pi converter, zeta converter, and SEPIC converter.

Types of DC/DC Converter

Step-down/buck converter: A buck converter or step-down converter is a type of non-isolated DC to DC converter that steps down from high input voltage level to a low output voltage level.

Step-up/boost converter: A boost converter or step-up coverter is a type of non-isolated DC-DC converter that steps up the low input voltage level to a high output voltage level.

Buck-boost converter: A buck-boost converter is a type of non-isolated DC-DC converter that converts an input DC voltage to output DC voltage by either lowering or boosting the voltage as required by the application.

Flyback converter: A flyback is a type of isolated DC-DC converter that can be used in both step-up and step-down configurations. It consists of a transformer, switch, rectifier, filter, and control circuitry to provide regulated DC output.

Forward converter: A forward converter is a type of isolated DC/DC converter that uses a transformer to step up or step down the output voltage and provide galvanic isolation for the load.

Key Specifications of a DC/DC Converter

Input Voltage: It represents the input DC voltage of the DC/DC converter and is expressed in volts (V).

Output Voltage: It represents the output DC voltage of the DC/DC converter and is expressed in volts (V).

Power Consumption: It represents the power consumed by the DC/DC converter and is expressed in milli-watts (mW).

Number of outputs: The switched-mode DC/DC converter provides multiple DC outputs as required by the application.