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How to Select a Dc-Dc Converter?

Jan 07,2023 | TCcharger

When deciding on a dc-dc converter, requirement specifications for packages are specific, and it is vital to specify the range of input voltages so that it will be implemented to the converter.

As with most electricity materials, a number one consideration when deciding on a dc-dc converter is to determine the output load power necessities of the gadget. The output requirements of the dc-dc converter encompass the output voltage and modern supplied by the converter. The output voltage might also have tolerance specifications dependent upon environmental conditions which includes enter voltage, output load contemporary, ambient temperature, and so forth. The load modern requirement specs have to include the minimal, maximum and ordinary values.

Requirement specifications for dc-dc converter packages are unique in comparison to ac-dc substances in that input voltages are not standardized, as they're for ac-dc strength materials. Whilst deciding on a dc-dc converter, it's far necessary to specify the variety of input voltages so that it will be applied to the converter.

Figure 1: Dc-dc converter system considerations

Remoted vs. Non-remoted Configurations

Dc-dc converters are available in either remoted or non-remoted configurations. Isolated converters are constructed with the enter and output circuits galvanically remoted; there's no dc direction between the input and output. These converters are regularly used to split the enter and output circuits for either electrical noise or dangerous voltage isolation. Isolated converters are available with a couple of output voltages from a unmarried converter.

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Non-isolated converters have a dc connection between the enter and output via the commonplace ground among the input and output circuits. This magnificence of converters may be made smaller and less highly-priced than remoted converters. A few non-isolated converters are able to producing a negative output voltage from a fantastic input voltage.

Figure 2: Isolated converter

Figure 3: Non-isolated converter

Regulated vs. Unregulated Output Voltage

Maximum dc-dc converters produce a tightly regulated output voltage, much like ac-dc components. Smaller or much less high-priced converters may be used in applications that may tolerate an unregulated output voltage. The selection of a regulated or unregulated output voltage is frequently to be had best on low-electricity converters.

Figure 4: Iout versus Vout graph for unregulated converter

Package and Mounting Choices

Dc-dc converters are to be had in a selection of package and mounting patterns. In programs in which the converter will be set up at once onto a PCB, there are picks of floor mounting (SMT) or through-hollow mounting (THM), as well as a single in-line pin (SIP) or dual in-line pin (DIP) configurations. Chassis-installed converters are available for applications requiring that fashion of mounting. Many converters are available in DIN rail mount configurations for industrial programs. Each open body and encapsulated converters may be located inside the maximum package deal and mounting configurations.

Figure 5: Package and mounting choices for dc-dc converters

EMI and EMC Concerns

Most digital merchandise presented for sale are required to satisfy EMI and EMC (Electromagnetic Interference and Electromagnetic Compatibility) regulatory necessities. The desires of the regulatory necessities are to make certain the goods do now not interfere with the operation of other products and that out of doors electrical noise does not save you the certified merchandise from running successfully. Dc-dc converters may be licensed to conform with regulatory requirements, however the finished gadget is licensed in most programs, and the inner sub-circuits do not require certification.

Safety Requirements

Much like EMI and EMC regulatory requirements, most digital products sold are required to satisfy regulatory protection necessities. As with the EMI and EMC regulatory certification, merchandise are granted safety certification for the final product, and certification is regularly not required for the internal sub-additives but can be obtained if essential. It need to be referred to that dc-dc converters bought within the eu and uk with enter voltage rankings of 75 V or extra require protection certificate, make certain of your necessities for other geographic locations. Protection certifications for converters should also be acquired if the dc-dc converters are used for setting apart customers of products from risky voltages.

Additional Features

Further to the traits of dc-dc converters discussed above, different features may be beneficial or required in product designs. A few converters permit the fashion designer to alter the output voltage with the use of external resistors. Excessive power converters often include load voltage experience terminals to enable the converter to make amends for voltage drops within the conductors among the converter’s output and the converter’s load. Including far off on-off capability lets in the clothier to enable or disable the output voltage from the converter with an electronic sign.

Figure 6: Application circuit showing output voltage trim, parallel outputs, and sense lines.