How to choose the right DCDC converter?

2025-11-19 10:22:08

Choosing the right DCDC converter is the key to ensuring stable, efficient and reliable operation of electronic systems. It is not just "just get the voltage right", but a systematic decision-making process. The editor of the following DCDC converter manufacturer has compiled a clear and practical DCDC converter selection guide. You can consider it step by step:

The first step: clarify the core electrical requirements - laying the foundation stone

This is the prerequisite for selection, which must be determined first.

Input voltage range: Determine what your power source voltage is (for example: 12V battery, 24V industrial power supply, 5V bus).

Key: The input voltage range of the DCDC converter you choose fully covers the entire range in which your source voltage may fluctuate, with some margin. For example, if you use a 12V car battery for power supply, you need to consider that the voltage may drop to 6V during cold start and may exceed 14V when the engine is running, so you should choose a converter with an input range such as 8-18V or wider.

Output voltage and current: Output voltage: Determine how stable the voltage your load requires (for example: 3.3V, 5V, 12V).

Output current/power: This is one of the key parameters. Calculate the total current requirements of all components of your system under heavy load and reserve a 20%-30% margin based on this. For example, if a large load requires 0.8A, it is RECOMmended to choose a converter with a rated output current of at least 1A. Maintaining margin helps improve reliability, prevent overheating, and extend life.

Isolation requirements:

Non-isolated converter: There is no electrical isolation between the input and output, and they are grounded together. The advantages are high efficiency, low cost and small size. It is suitable for occasions that are sensitive to space and cost, and the input and output ground potentials do not need to be isolated (such as local conversion of voltage within the board).

Isolated converter: The input and output are electrically isolated through a transformer. The advantages are:

Safety: Prevent high voltage from escaping into the low voltage side and protect personnel and equipment.

Anti-interference: Break the ground loop and improve the system's anti-noise capability.

Level conversion: The ground potential reference point can be changed.

Suitable for industrial sites, medical equipment, communication interfaces and other scenarios that require high safety and reliability.

Step 2: Evaluate key performance indicators—pursue quality

These indicators determine the performance, efficiency and applicability of the converter.

efficiency:

The higher the efficiency (η = Pout / Pin), the less energy loss (heat). This is critical for battery-powered devices (to extend battery life) and high-power applications (to reduce thermal stress).

Look at the efficiency curve in the data sheet, not just the peak efficiency. Pay attention to the efficiency value at your typical load current.

Ripple and noise:

This is the high-frequency noise on the output DC voltage. For analog circuits (such as sensors, audio) or high-speed digital circuits, excessive ripple noise can interfere with system performance.

Make sure the large ripple noise value stated in the data sheet is lower than the tolerance range of your load.

Quiescent current:

For battery-powered portable devices, when the system is in standby or sleep mode, the power consumption of the converter itself is mainly determined by the quiescent current. The lower the quiescent current, the longer the standby time.

Linear regulation rate and load regulation rate:

Linear adjustment rate reflects the stability of the output voltage when the input voltage changes.

Load regulation reflects the stability of the output voltage when the load current changes.

The smaller these two values ​​are, the more stable the output of the converter is.

Step 3: Consider environment, size and reliability - adapt to reality

Working temperature range:

​Determine what ambient temperatures your equipment will operate at. If the ambient temperature is high (such as industrial control cabinets, automobile engine compartments), choose a module with a higher rated operating temperature (such as -40°C to +85°C or 105°C), and pay attention to the derating curve (that is, the power usage needs to be reduced at high temperatures).

Dimensions and packaging:

​Measure the available space on your PCB. DCDC converters come in various forms such as chip type, plug-in type, open module and sealed metal package. Make sure its physical dimensions and pinout match your design.

Protection function:

The built-in protection circuit can significantly improve the robustness of the system. Must-have features typically include:

Overcurrent protection

Short circuit protection

Over temperature protection

For scenarios where the input voltage may fluctuate significantly, overvoltage/undervoltage lockout is also very useful.

Step Four: Comprehensive Decision-Balance and Choice

Cost and supply:

Compare prices from different suppliers while meeting all technical, safety and reliability requirements.

Be wary of a price that is too low, it may mean cutting corners or making false specifications.

Confirm the supplier's delivery cycle and stability to avoid affecting mass production.

Supplier technical support and documentation:

Choose a supplier that can provide complete data sheets, application notes, reference designs and simulation models. Excellent online selection tools and technical support can help you save a lot of development time.

Summary: Overview of the selection process

Define requirements list: List all requirements such as input/output voltage and current, isolation, size, temperature, etc.

Screening topology: Based on the relationship between input and output voltages, initially determine whether it needs to be buck, boost or buck-boost.

Determine key performance: Clear priorities for efficiency, ripple, and quiescent current.

Market research: Use the supplier's selection tool to screen out several potential models.

Dive into the data sheet: Carefully read the PDF of the candidate model, focusing on its key parameter curves, layout recommendations, and derating information.

Request Samples and Testing: This is an important step! Test under actual or simulated final conditions to verify whether its performance (especially temperature rise and dynamic response) meets the requirements.

Remember the core principle: There are no "very good" DCDC converters, only "good" ones. The right choice is based on a deep understanding of the application and the perfect balance between performance, cost, size and reliability.