As the name suggests, a DC/DC converter is an electronic circuit or device that converts direct current (DC) sources from one voltage level to another. In other words, a DC/DC converter takes as input a DC voltage and outputs a different DC voltage. The output DC voltage levels are rated from very low to very high, which can be higher or lower than the DC input voltage. Typically, DC/DC converters can be classified into three types according to the type of voltage conversion: step-up (Boost) DC/DC converters, step-down (Buck) DC/DC converters, and Buck Boost DC/DC converters. Engineers can choose the right dc-dc converter for their system depending on their needs for different output voltages in various applications.
MORNSUN‘s 0.2-400 watts DC/DC converters portfolio
The purpose of DC/DC converters
DC/DC converters are widely used in industrial control, electric power, communication, transportation, security, instruments, medical, automotive, IoT, new energy, computers, office automation equipment, military, aerospace and other fields, involving all walks of life and play an increasingly important role in the economy. In these various applications, there are many electrical devices and circuits that require lower or higher voltages than those provided by the power source. In this case, we need a circuit to convert or change the level of the voltage input received.
Before the DC/DC converters were invented, engineers had no alternative converter to choose from, thus the use of vibrators, rectifiers, and transformers (boost or buck) became common. However, the disadvantages were obvious as well. Their large size leads to poor flexibility in use, and when they worked, they were very inefficient and waste a lot of energy in the form of overheating.
With the trends toward miniaturization, more and more applications require voltage transforming devices with compact size, lightweight, high efficiency and high reliability. DC/DC converters have been widely used in many sectors due to their smaller size, outstanding performance and flexibility of use, which has greatly solved the challenges faced by the previous voltage conversion solutions. DC/DC converters allow for the conversion of voltage in an extremely efficient manner, making them ideal for use in today’s modern devices such as laptops and IoT equipment.
Let’s look at the five main functions of DC/DC converters.
- Voltage conversion: boost conversion, buck conversion, polarity conversion (positive and negative polarity conversion, single power supply and positive and negative power conversion, single power supply and multiple power supplies Conversion)
- Safety isolation: strong and weak current isolation, lightning isolation protection (such as isolation protection of medical electronic equipment in contact with the human body), IGBT isolation drive, surge isolation protection, all of which are the isolation required for the human body safety.
- Noise isolation: signal isolation (analog circuit and digital circuit isolation), in order to avoid the affection of the communication between devices. Let’s take the example of a sensor that the signal detected is inaccurate, for example, the value detected is too large resulting in a false alarm of temperature. Noise isolation to avoid the devices interfering with each other.
- Ground loop clearance: for example, the strong and weak signal isolation of field-bus systems, the remote energy transmission such as distributed power distribution system. A ground loop tends to deteriorate the stability of the system and damage the end devices.
- Multiple protections: short circuit protection, over-voltage protection, under-voltage protection, over current protection, input anti-reverse connection, and other protections, etc.
- Voltage stabilization: remote DC power supply, distributed power supply system, battery power supply.
- Noise reduction: active filtering.
Basic parameters of DC/DC converters
The basic parameters of a DC/DC converter include package format, isolation voltage, power, input voltage and output voltage.
- Package format: the size and output form of DC/DC converters with different power varies greatly. Package formats include SIP, DIP, SMD, half-brick, quarter-brick, open frame and so on. Small power products with sealed shells have a very compact shape, while high power products usually come in a quarter-brick or half-brick format, with circuits either exposed or wrapped in the enclosures.
- Input voltage: fixed input voltage, wide input voltage and non-isolated DC/DC converter can be selected according to different input voltage ranges. Fixed input voltage DC/DC converters typically allow 3.3VDC, 5VDC, 12VDC, 15VDC, 24VDC, and 48VDC input voltages. The wide input voltage DC/DC converter support 2:1/4:1 /7:1/8:1/12:1 input voltage ranges , covering 4.5-9VDC, 9-36VDC, 36-75VDC, 40-160VDC and so on. The wider the input voltage range, the better, but the cost also raises.
- Output voltage: The voltage output by the DC/DC converter will be used to power the related electronic devices or circuits of the system. The required output voltage and the number of outputs depend on the actual needs of the user’s system. Common output voltages are 3.3V, 5V, 9V, 12V, 15V, 24V, 28V, 48V, ±5V, ±9V, ±12V, ±15V.
- Isolation voltage: The maximum voltage applied between input and output that the converter can withstand within a certain time limit (usually 1 second), called the isolation strength of the converter. Different applications require different levels of isolation voltage. Typically, isolated voltages range from 1000VDC, 1500VDC, 3000VDC, 6000VDC to 12000VDC and higher. In general, the isolation voltage required for DC/DC converter is not very high, for example, 1500DC/3000VDC can meet the needs. While for electric power applications, isolation should be as high as 3000VAC. Usually, medical equipment requires a higher isolation voltage to ensure a low leakage current and avoid harm to the human body. Thus, 4200VAC/6000VDC reinforced insulation is required.
- Output power: The output current can be determined once the load is confirmed. The load current determines the output power and affects the converter’s reliability and cost. When the DCDC converter operates at a high temperature, it should be derated use. For detailed information please refer to the derating curve in the datasheet.
Selection criteria of DC/DC converters
How to choose the right DC/DC converter for different applications is one of the factors determining the success of the prototype stage of a project. By selecting the appropriate DC/DC converter, engineers can simplify the process of power design and debug, and able to focus on their own professional fields, which can not only improve the power design level and reliability of the overall system but also shorten the whole cycle of product research and development and the time to the market. This will help them to win valuable business opportunities and drive the growth of their industry in a fiercely competitive market.
There are several criteria when selecting a DC/DC converter: input voltage range, output voltage, rated power, package format, isolation voltage, operating temperature range and derating, power consumption and efficiency. Below we will review more details on these selection criteria.
- Input voltage range and output voltage. Select a DC/DC converter that meets the parameters based on the power supply requirements. For example, a 1W fixed input DC/DC converter is ideal for signal isolation RS485. For industrial bus power supply (24V), communication bus power supply (48V), railway power supply (110V), transformer rectifier output (220V), all kinds of batteries (lithium batteries, dry batteries, etc.) and long-distance transmission such as photovoltaic distributed power supply system, DC/DC converters with a wide input voltage range will be suitable solutions.
- Rated power. It is recommended that the actual power used is 30% to 80% of the rated power of the DC/DC converter. The performance of the DC/DC converter working in this power range is in full play and stable. A light load wastes resources, while a heavy load adversely affects temperature derating and reliability. In case of high temperature, the converter should be derated use. It is recommended that the converter is used at a power reduction of 70% at the corresponding temperature. In the case of high temperature and poor heat dissipation conditions, the module with a larger size or bigger package is preferred when with the same power. Please contact our technical team for more information if the converter is required to be used at a high temperature of over 70℃ for a long time.
- Package format. There are various package formats, products with the same power have different packages while the same package would have different powers. It needs to take dimension, cost and the converter’s reliability into account. Enough space should be reserved for the converter to reduce the interference to signal acquisition as its thermal radiation and the interference to other circuit components. The selection principle is to select a suitable format of DC/DC converters according to the power and installation method of the system. It can be mainly considered from these three aspects. A. Try to choose a converter with international standard packages. B. The volume should be as small as possible within certain power, so as to give more space and more functions to other parts of the system. C. It should be extensible to facilitate system expansion and upgrade. In such a case, the package of the DC/DC converter along with the design of the system circuit can remain unchanged, which greatly simplifies product upgrades and saves time.
- Isolation voltage. Choose a DC/DC converter with suitable isolation voltage according to different applications. The isolation strength is higher than the rated working voltage of the converter. In addition, the leakage current specification of the device needs to be considered when selecting an isolated DC/DC converter. The leakage current increases with increasing noise voltage and decreases with decreasing isolation capacitance. Therefore, when designing a low-noise power supply, a DC/DC converter with high isolation strength and low isolation capacitance should be selected to reduce leakage current. Higher isolation voltage can ensure that the DC/DC converter has less leakage current, better EMC performance, higher safety and reliability. However, the balance between cost and performance throughout the design process is another factor to consider.MORNSUN’s UWTH1DxxQB-100WR3 Series DC/DC converter achieves 3000VAC input to output reinforced insulation:
- Operating temperature range and derating. DC/DC converters are available in several operating temperature ranges: commercial-grade, industrial-grade, military-grade, etc. When choosing a DC/DC converter, the actual operating temperature range must be considered. Because of different temperature grades, different materials and manufacturing processes, the price will vary greatly. Improper selection will also affect the use. There are two selection methods for reference: one is to choose according to the power used and the package format. If the actual power used is close to the rated power with a certain volume (package format), then the nominal temperature range of the converter must be strict, even should leave a slight margin to meet the actual needs. The other is to choose according to the temperature range. If choosing a converter with a smaller temperature range due to cost considerations, but sometimes the working temperature of the converter is close to the limit, you should refer to derating at this time. That is, choose a DC/DC converter with a larger power or package.
- Power consumption and efficiency. The power of an isolated DC/DC converter is generally about 80%, and the power of a non-isolated DC/DC converter is about 90% or even higher. This full load efficiency could be found in the datasheet of the converter. At a certain output power, the smaller the power loss of the module, the higher the efficiency, which enables lower temperature derating, longer life and energy-saving.
MORNSUN DC/DC Converter solutions for various industries
Reliable power supplies are indispensable for powering the increasingly complex infrastructure and systems used by various industries and guaranteeing the high performance, safety and reliability of the overall system. Engineers should research carefully to select the most reliable power supply manufacturers for their electrical projects. MORNSUN has over 23 years of R&D experience providing reliable power supplies that meet the main industry quality standards. It has expanded its portfolio to include a series of DC/DC converters for a wide range of applications. For example, our recommended railway power supplies include the 6-400W URx1D series with 4:1 input DC/DC converter and the 50-200W UWTH1D series with 12:1 input DC/DC converter. These railway DC/DC converters are EN50155 certified and designed for use even in the harshest environments.
Below we will shed some light on the key features of MORNSUN’s new 100W railway DC/DC converter UWTH1DxxQB-100WR3 series with 1/4-Brick packaged.
- Ultra-wide input voltage range of 14-160VDC, suitable for the global mainstream railway systems
- Meet the EN50155 hold-up time of 10ms with the optimal and cost-effective peripheral
- Programmable input Under voltage adjustment
- High I/O isolation voltage up to 3000VAC, meets 5000m altitude requirements
- Operating temperature range of -40℃ to +105℃
- No-load Input Power as low as 0.6W
- Input reverse polarity protection
- Meet CSA/EN62368/IEC62368, EN50155, EN45545 standards
DC/DC converters for railway applications can be used either on-board or off-board. In particular, they have often used to power the following equipment.
Rail transit equipment powered by DC/DC converters
DC/DC converters for railway applications need to guarantee reliable and stable power under all circumstances. Whatever their exact application, the performance requirements for railway power solutions are challenging on several fronts. Failures can not be tolerated, even under extreme mechanical stress over an extended temperature range. For this reason, there are several factors to consider when designing the circuitry for railway power supply systems:
Factors to consider for railway power supply systems
Tens of thousands of MORNSUN DC/DC converters have been installed on diverse Trackside equipment, Station equipment and On-board train systems globally. Below is the power solution for air conditioning controller application in railway. Power supplies required need to provide a strong anti-interference ability and allow high isolation. MORNSUN’s UWTH1D24QB-100WR3 series DC/DC converter with ultra-wide 14-160VDC input is the optimal solution to meet 3000VAC reinforced insulation design requirements. Rated at 100 watts, the module delivers a wide operating temperature range of -40℃ to +105℃, shock & vibration resistance, high efficiency as high as 90% and excellent EMC performance, which is EN50155 certified and widely used in vehicle-mounted switches, train control systems and associated equipment.
MORNSUN‘s power solution for air conditioning controller application in railway
By adding the FC-C08D filter module to the front end of the DC/DC converter, it can ensure the system compliant with the EMC requirements of EN50155. When used with MORNSUN’s DC/DC railway converter module, the maximum input voltage of the converter should not exceed the maximum voltage rating of the FC-C08D filter.
Features of FC-C08D EMC filter:
- Ultra-wide 12:1 input voltage range: 14 -160VDC
- High efficiency up to 98%
- Operating temperature range of -40℃ to +105℃
- Meet EMC standard: IEC/EN61000-4, CISPR32/EN55032
- Meet the railway standard: EN50100, EN50121-3-2
- Meet the safety standard: EN62368
With over 23 years of experience in the power supply industry, MORNSUN can provide a more holistic range of solutions to meet different customers’ needs. Contact MORNSUN to request more information, support, sample, or discuss with our field application engineers your exact power supply requirements for your electrical projects.
Masters is the official distributor of MORNSUN products. If you are interested in receiving samples or want to talk about your project and possibilities of using MORNSUN components, please contact us at email@example.com or directly with chosen customer service office. We will advise the most appropriate solution to your needs.