DC-DC converters – what’s, why’s and how’s
A power converter is one of the most important components in electrical engineering – it converts electric power from one form to another or one frequency to another. One way to classify power conversion systems is whether the input and output are alternating current (AC) or direct current (DC). Therefore, you can have DC-DC, AC-AC, AC-DC and DC- AC power conversion systems.
- What is a DC-DC converter?
A DC-DC converter is an electronic circuit that transforms DC voltage from one voltage level to another. Normally, power converters contain large and bulky transformers and inductors, which limit their efficiency, power density and reliability. DC-DC converters are a class of power converters that are small, lightweight, and highly efficient. DC-DC converters are used to amplify DC voltages or to invert input DC voltages and output them as negative voltages. A DC-DC converter uses a semi-conductor switch device to convert a DC voltage, and conducts feedback control to maintain an output voltage.
- Uses of DC-DC converters
DC-DC converters are frequently used in computer systems and portable electronic systems such as laptop computers, cellular phones, digital cameras, and personal digital assistants (PDAs). These are often supplied with power from batteries or external supplies and contain several sub-circuits that require different voltage levels, different from that supplied by the battery or external supply.
- How do DC-DC converters work?
A DC-DC converter includes a step-down circuit, which produces a DC output voltage that is lower than a power supply voltage, and a step-up circuit, which generates a DC output voltage that is higher than the power supply voltage. They do this by receiving the incoming DC voltage from the power source or battery, chopping it at a high frequency, and then filtering it to provide the required output DC voltage. The DC-DC converter also includes a control circuit which receives switching signals from an external device to switch the mode from a step-up to a step-down operation, or vice versa. DC-DC converters can increase voltage from a lower battery voltage. This means that you do not need to use multiple batteries and can save space in your electronic system. In other cases, converters maintain a constant voltage value of the power sources that have varying voltages with time. A good DC-DC converter will have protection against overload, over voltage, over temperature, and short circuits. Also features such as free air convection for cooling, low ripple noise, a metal case shield, low cost and high reliability are desirable.
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