【Explanation】DC/DC converter You can easily understand the basics of DC/DC converter!

DC/DC CONVERTER  KNOWLEDGE

The input voltage of the DC/DC converter is direct current (DC), and the output voltage is also direct current (DC). It is an on-board power supply that uses a lot of chip parts and is miniaturized so that it can be mounted directly on a printed circuit board like other electronic parts. Taking advantage of its small size and thinness, it is used in equipment in a wide range of industries such as communication equipment. This DC/DC converter and AC/ DC converter are combined to supply the optimum voltage and current to equipment and devices.

The optimum voltage and current of each load electronic component are different. Standard voltages are 12-14V for motors, 5V or 12V for HDDs, ± 12V for op amps, 3.3V or less for HIC, and so on. In addition, the voltage supplied to electronic components is required to be stable against the input voltage of the DC/DC converter and sudden changes in load.

 

It is laptop computers that use DC/DC converters around us. Many DC/DC converters are used to convert the voltage of a laptop battery to the input voltage of electronic components such as 3.3V, 5V, and 12V. The voltage of the battery changes greatly depending on the charge and discharge, but the output voltage of the DC/DC converter is controlled to be constant at all times. Thanks to this DC/DC converter, the electronic circuits of the laptop computer are operating normally.

Types of DC/DC converters

　

DC/DC converters are roughly divided into “insulated type” and “non-insulated type”. Insulation means that the primary side and the secondary side are not electrically connected, and non-insulation means that the primary side and the secondary side are not electrically connected. To put it simply, it is insulated if a transformer is used, and non-insulated if it is not used.

In other words, a non-isolated circuit that does not use a transformer is called a “chopper”. If you use a chopper circuit, you can step up or down the DC voltage, but you cannot step up or down too much. Practically, the limit is about 10 times the step-up pressure for step-up and about 1/10 for step-down. When a higher buck-boost is required, use an isolated DC/DC converter with a transformer inside the circuit.

Insulated DC/DC converter

DC/DC converter that has a transformer is called an isolated DC/DC converter. The transformer has an important function of input/output isolation, and if this function is required, use the transformer even if the buck-boost ratio is small. It is a highly reliable full-scale power supply that can handle large-capacity power supplies. However, since it has a built-in transformer, it is difficult to reduce the size and cost.

The switch element (transistor) of the DC/DC converter operates at high frequencies of several tens of kHz to several hundreds of kHz. Transformers have the property of becoming smaller as the frequency increases, and the oscillation frequency of DC/DC converters is smaller and lighter in units of KHz compared to transformers that operate at 50Hz or 60Hz.

Also, electrical circuits that may come into contact with humans must be “insulated” by this transformer from dangerous voltages. There are various connectors on the side of the laptop computer, which can be easily touched by humans, so the circuit of the laptop computer is insulated from AC100V with a transformer. Therefore, isolated DC/DC converters are always used in the DC/DC converters of laptop chargers. Thanks to the transformer of the isolated DC/DC converter, you can use your laptop with confidence.

 

Non-isolated DC/DC converter

The chopper circuit is also called a non-isolated DC/DC converter. Since the non-isolated DC/DC converter does not use a transformer, it has the advantage of being small and inexpensive. Electrically, the primary side and the secondary side are electrically connected, but there is no risk of electric shock because the output voltage is low such as 1.8V, 1.5V, 1.3V, 0.8V.

Also, by not using a transformer, there is an advantage that a non-isolated DC/DC converter can be mounted near the load (IC) of the printed circuit board because it is highly efficient, generates less heat, and does not require a heat sink.

A typical non-isolated DC/DC converter is “POL”. POL is an abbreviation for “Point of Load” and means proximity of loads. Placing a POL in front of the load IC reduces voltage drop and makes it less susceptible to noise.

DC/DC converter shape

There are several types of DC/DC converters by shape. “Onboard”, “POL”, “power module”, etc. I will explain each of them.

 

Onboard

Onboard is a type of DC/DC converter that is mounted directly on the board. DC/DC converters often refer to this type, and various models are available from various manufacturers.
The size notation is not only the onboard type, but the inch notation is the world standard. Since the board type is small, 1×1 inch (one-by-one), 2×1 (two-by-one) inch, and 2×2 (two-by-two) inch are easy to understand. There are many other inch sizes that are not integers. In short, it’s just written in inches.

The DC/DC converter of a domestic power supply manufacturer is the original size in mm notation, but recently it has been released in inch size such as 1×1 which is the world standard. The type in the photo is the CCG series made by TDK-Lambda, which is the world’s smallest class of 1×1 (one-by-one) size at 30W.

Input voltage is DC3.3V, 5V, 12V, 15V, 24V, 48V. Recently, as the number of battery input devices has increased, wide input types such as DC12 to 24V and DC24 to 48V are also on sale. The output voltage is low voltage of DC3.3V, 5V, 12V, 15V where electronic components operate. It has a capacity of about 1.5W to 80W and does not use an electrolytic capacitor, which is a long-life component, so it has no electric capacitor life.

There are two output voltages, single output and two outputs. The single output is generally 3.3V, 5V, 12V, 15V, and the two outputs are ± 12V, ± 15V.

POL

A highly efficient, compact, high-speed responsive non-isolated DC/DC converter that converts an intermediate voltage such as 48V to the low voltage required by electronic components such as ICs.
Input voltages are available in relatively high input voltage types from 9 to 50V and low voltage input types from 4 to 14V. The output voltage of the high input voltage type can be changed from 3 to 40V, and the output voltage of the low voltage input type can be changed by about 0.6 to 5V. The current value is generally up to 30A, but there is also BRFS150 made by Cosel that can carry a large current of 150A.

 

Power module

The power module is also soldered directly to the pins on the board. For heat dissipation, attach a heat dissipation fin to the aluminum base plate on the opposite side of the pin and blow the wind, or make it adhere to the metal part of the device body to dissipate heat.

The standard unit of power module is called “brick”.
Brick means brick, and full brick is about 117mm in length x 61mm in width x 117mm in height. The 1/2, 1/4, 1/8, and 1/16 sizes are called Half Brick, Quarter Brick, Ace Brick, and Sixty Brick, respectively. The power module in the photo is a 1/4 brick. This brick size is not exact and may vary slightly depending on the model.

The power module cannot be used alone, and peripheral circuit design is required. A power module is, so to speak, a package of a part of a power supply circuit. Considering that users design power supplies with discrete parts, using power modules makes circuit design easier and saves design man-hours. It has a capacity of up to 700W and various options are available.

Distributed power supply system

The operating voltage (input voltage) of electronic components differs depending on the load characteristics, functions, and capacitance. Many electronic components operate on low voltage direct current (DC).

As electronic devices become more multifunctional and digital, the DC voltage required by electronic components is 12V, 5V, 3.3V, 2.5V, 1.8V, 1.3V, 1.0V, 0.8V, etc., and Low voltage and large current are progressing.
Until now, multiple independent DC / DC converters were installed in the equipment, but recently, from the viewpoint of efficiency and noise suppression, a small DC / DC converter (POL) has been installed near the load (IC) on circuit board.  “Distributed power supply system” that is distributed and arranged has become mainstream.

Conventionally, a system that supplies power from an ACDC power supply to a load via a DCDC converter, a DCDC converter, and a system that sandwiches a POL between the load.

 

Source: TDK Power Electronics World

In the past, commercial power was converted to DC48V using an AC/DC switching power supply, and three DC/DC converters were mounted on the board to supply DC5V, DC3.3V, and DC2.5V to load I C. However, there is too much difference between the input voltage of 48V and the output voltage of 2.5V, resulting in poor efficiency.

To solve this problem, the DC/DC converter should be placed as close to the IC as possible. There is only a small POL (Point of Load) that generates less heat and does not require heat dissipation fins.

Global market size of DC/DC converter

 

According to a 2019 survey by Markets and Markets, the global market size of DC/DC converters is expected to grow from an estimated $ 8.5 billion to $ 22.4 billion in the next 2025. It is a considerable increase because we expect it to increase 2.6 times from $ 8.5 billion to $ 22.4 billion in five years. (The influence of the new corona is not taken into consideration, so it is just “Behore Corona”.)

The fastest growing market for DC/DC converters is the “automobile market,” which includes FCVs (fuel cell vehicles), EVs (electric vehicles), HEVs (hybrid electric vehicles), and PHEVs (plug-in hybrid electric vehicles).

* Markets and Markets is a market research company established in 2001 in the United States. It is the world’s second largest publisher of market research reports, and more than 700 full-time analysts publish more than 900 market research reports annually.

In addition, the global market for switching power supplies (including DC/DC converters) of Micro Technology of the United States in 2018 is $ 40.7 billion, so AC/DC power supplies will be about 80% and DC/DC converters will be about 20%. is. I think it fits my senses.

Major DC/DC Converter Companies

• TDK-Lambda Co., Ltd.
• Murata Manufacturing Co., Ltd.
• DELTA ELECTRONICS, INC. ・・・a Taiwanese manufacturer established in 1971, is a large corporate group with approximately 87,000 employees and sales of approximately US $ 7,345 million worldwide. Our main products are various electric and electronic parts such as switching power supplies and fans. In recent years, we have been developing solutions and business for solar panels.
• INFINEON TECHNOLOGIES AG  ・・・ Established in 1999, Germany (Munich headquarters) with 40,000 employees is an in-vehicle and industrial semiconductor manufacturer.
• ARTESYN EMBEDDED TECHNOLOGIES ・・・ Established in Florida, USA in 1868, manufactures isolated DC-DC converters for industrial applications in areas such as automation, instrumentation, testing and measurement, and communications.
• ASEA BROWN BOVERI LTD. ・・・Established in 1988. A multinational company headquartered in Switzerland, it is one of the four major industrial robot manufacturers, mainly engaged in electric power-related, heavy electric and heavy industry businesses. With 850 subsidiaries operating in 140 countries, 180,000 employees and $ 50 billion in sales.
• TEXAS INSTRUMENTS INCORPORATED.・ ・ ・ Established in 1951 in Dallas, USA, a semiconductor manufacturer with manufacturing, design and sales bases in more than 30 countries around the world. The world’s largest analog IC company, with its main products being DSPs that perform digital signal processing indispensable for the digital information home appliances, wireless, and broadband markets, and related analog ICs and microcontrollers.
• FLEX LTD. ・・・ Flex is an EMS company in Singapore. The company name was changed from Flextronics in July 2015. With 2008 sales of approximately $ 36 billion, it is the second largest EMS company in the world.
• VICOR CORPORATION ・・・Established in Massachusetts, USA in 1981. Modular DCDC converter manufacturer
• FDK Corporation
• TRACO ELECTRONICS AG・・・A Swiss company with over 35 years of experience as a major power supply specialist. We provide high-quality DC / DC converters and AC / DC converters for industrial applications such as railways, medical care, automobiles, renewable energy, and smart grids.
• RECOM POWER GMBH ・・・ Austrian power supply manufacturer with a track record of 45 years. Manufactures AC / DC power supplies, DC / DC converters, switching regulators and LED drivers.
• CRANE AEROSPACE & ELECTRONICS ・・・A US manufacturer with 2,800 employees. Manufactures sensors, power, brakes and electronics.
• STMICROELECTRONICS: A semiconductor manufacturer headquartered in Geneva, Switzerland. A multinational manufacturer with offices in 35 countries around the world.
• BEL FUSE INC.