DC-DC Converter Chips Information

Last revised: October 25, 2024
Reviewed by: Scott Orlosky, consulting engineer

DC-DC converter chips provide a regulated DC voltage output from a different, unregulated input voltage. They are used in power management applications and incorporate several conversion technologies.

Buck or step-down converters convert a higher DC input voltage to a lower DC output voltage of the same polarity. Using a transistor as a switch, buck converters alternately connect and disconnect the input voltage to an inductor.

Boost or step-up converters convert a lower DC input voltage to a higher DC output voltage of the same polarity. Buck-boost converters can be used for either step-up or step-down conversions, and to reverse or invert voltage polarity.

CUK converters use capacitive energy transfers, creating a smooth current at both sides of the converter. Charge pump converters are suitable for voltage step-up or voltage inversion in low power applications.

Unlike most other DC-DC converter chips, charge pumps store energy in a capacitor instead of an inductor. Flyback converters are similar to buck-boost converters, but use a transformer to store energy and provide isolation between the input and output. These devices have two distinct phases for energy storage and delivery. Forward converters are similar to flyback converters, but use transformers in a more traditional manner, transferring energy from input to output in a single step.

Important Specifications

  • Output voltage
  • Input voltage
  • Output current
  • Quiescent current
  • Switching frequency
  • Efficiency
  • Operating temperature

Both the output regulated voltage (VOUT) and the input voltage (VIN) are minimum and maximum amounts in continuous mode (DC). The output current (IOUT) is measured under specified conditions. Measured in amperes (A) during the idling state, the quiescent current never makes it to the load. Instead, it flows from the battery to power the regulator itself.

Efficiency, the ratio of output power to input power, measures the ability of DC-DC converter chips to convert input energy into output energy. For example, an efficiency of 100% means that all of the input energy is transferred to the output.

Features

DC-DC converter chips are available with a variety of features. Some devices have more than one output or channel. Others have an internal circuit to control the amount of current produced, or an error flag for monitoring outputs that drop below a nominal value.

Reverse voltage protection prevents damage in applications where users can accidentally reverse battery polarity. Thermal shutdown protection turns off DC-DC converter chips when the temperature exceeds a predefined limit. Shutdown (inhibit) pins are used to disable regulator outputs.

For switching applications, converters sometimes use metal-oxide silicone field-effect transistors (MOSFET) instead of diodes. Synchronous rectification means that the MOSFETs are turned on and off at the right time for efficient gating or rectification of the output.

Packaging

TO-92 is a single in-line package used for low power devices. TO-220 is suitable for high power, medium-current, and fast-switching products. TO-263 is the surface-mount version of the TO-220 package. Other IC packages for DC-DC converter chips include shrink small outline package (SSOP), small outline integrated circuit (SOIC), small outline package (SOP) and small outline J-lead (SOJ).

Standards

SMD 5962-98529 — Microcircuit, hybrid, linear, 15-volt, dual channel, dc-dc converter.

DC-DC Converter Chips FAQs

How do the different types of DC-DC converters impact efficiency and performance in power management systems?

DC-DC converters are designed to efficiently transfer energy from a DC voltage source to a load. The efficiency of a converter determines how much input power is effectively converted to output power. For example, a buck converter's efficiency increases with the duty cycle and peaks at 100% duty cycle, while a boost converter's efficiency increases with a decrease in the duty cycle and is maximized when the duty cycle is 0%.

Switch-mode power supplies (SMPS), including LLC converters (L means an inductor and C refers to a capacitor), are known for superior power conversion efficiency. These converters reduce switching losses, but require sophisticated controllers to manage multiple resonances.

In spacecraft systems, high-efficiency DC-DC converters are essential as they reduce power consumption, allowing for smaller and lighter power source components. This results in less mass and volume for power sources like solar arrays and batteries, which is critical in space applications.

Resonant DC-DC converters are used in high-voltage applications to smooth waveforms and improve energy efficiency, which is particularly beneficial in electric vehicles.

The choice of components, such as diodes and power switches, significantly affects the efficiency and performance of DC-DC converters. For instance, Schottky diodes are favored in buck-boost converters for their low forward voltage drop and fast switching capabilities, although they may have high reverse leakage current.

The selection of power switches in step-down converters determines the power conversion efficiency for servers and telecom applications.

Designing a DC-DC converter often involves trade-offs between cost, performance, and size. A properly designed converter can achieve an efficiency greater than 90% at full load.

What is the role of resonant converters in power management systems?

Resonant converters are used to enhance efficiency and performance, particularly in high-voltage applications.

Resonant converters are a type of switching-based converter that incorporate a resonant tank to control the power flow from input to output. This design helps in reducing switching losses, which is a common issue in traditional converters.

By minimizing these losses, resonant converters improve the overall energy efficiency of the system. This is particularly beneficial in applications like electric vehicles, where efficient power conversion can lead to longer travel distances on a single charge.

Resonant converters are commonly used in high-voltage applications to smooth waveforms and improve energy efficiency.

To achieve the increased efficiency offered by resonant converters, sophisticated controllers are necessary. These controllers manage the multiple resonances within the converter, ensuring optimal performance and efficiency.

What are the challenges in designing resonant converters?

Designing resonant converters presents several challenges, primarily due to their complex nature and the need for precise control to achieve high efficiency.

Sophisticated controllers are used to manage multiple resonances within the converter. This complexity arises because the resonant tank circuit, which is integral to the converter's operation, must be precisely controlled to minimize switching losses and optimize efficiency.

The choice of components, such as diodes and power switches plays a large part in determining performance. For instance, Schottky diodes are often used for their low forward voltage drop and fast switching capabilities, but they can have high reverse leakage current, which increases with temperature. Selecting the right components is a trade-off between performance, cost, and efficiency.

All resonant converters, like other power converters, generate heat during operation. Efficient thermal management is necessary to prevent overheating and ensure reliable performance. This involves designing appropriate heat sinks and considering the thermal properties of the components used.

Efficiency and performance of resonant converters can also be affected by changes in load. The control system must be able to adapt to varying load conditions to maintain optimal performance.

The design of resonant converters is inherently more complex than traditional converters due to consideration of all the factors that affect their overall performance. This complexity can lead to longer development times and increased design costs.

How do component choices affect the performance of DC-DC converters?

Diodes

The type of diodes used can influence power conversion efficiency. Schottky diodes are commonly used in buck-boost converters due to their low forward voltage drop and fast switching capabilities. However, they may have high reverse leakage current, which increases with temperature, potentially affecting efficiency negatively.

Power Switches

For example, in step-down converters used in servers and telecom applications, the choice of power switches can impact efficiency and power density. Manufacturers like Infineon Technologies offer advanced power switch solutions that enhance efficiency and are compact.

Component Trade-offs

Designing a DC-DC converter involves trade-offs between cost, performance, and size. The selection of components must balance these factors to achieve the desired efficiency and performance. A properly designed DC-DC converter can achieve an efficiency greater than 90% at full load.

Thermal Management

Components such as diodes and power switches generate heat during operation. Efficient thermal management is necessary to prevent overheating and ensure reliable performance. This involves designing appropriate heat sinks and considering the thermal properties of the components used.

Load Variability

The efficiency and performance of DC-DC converters can be affected by changes in load. The control system must be able to adapt to varying load conditions to maintain optimal performance.

What is the impact of thermal management on DC-DC converter performance?

Thermal management directly influences the efficiency, reliability, and longevity of the converter. Much of this is due to selection of components, especially power switches and diodes.

Heat generation is primarily due to the losses in components like diodes and power switches. It is necessary to dissipate this heat to prevent overheating, which can lead to reduced efficiency and component failure.

High-efficiency converters generate less heat, allowing for smaller and lighter heat sinks and other thermal management components. This is particularly beneficial in applications like spacecraft systems, where reducing size and mass has a high value.

Proper thermal management involves designing appropriate heat sinks and considering the thermal properties of the components used. This ensures reliable performance and prevents thermal-related issues that could affect the converter's efficiency and lifespan.

Effective thermal management contributes to maintaining optimal performance under varying load conditions. It ensures that the converter operates within safe temperature limits, thereby enhancing its reliability and efficiency over time.

DC-DC Converter Chips Media Gallery

References

Electronics360—The first space-qualified GaN DC-to-DC power converter

GlobalSpec—Tips to improve power conversion efficiency

GlobalSpec—White Paper: Looking Closer at Filter, Resonant and Snubber Capacitors in Electric Vehicles

Image Credits:

Toshiba America, Inc. | Fuji Electric Corp. of America


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