Analysis of core performance parameters of ACDC converters

2025-11-19 10:13:12

The performance of the ACDC converter directly determines the efficiency, stability, reliability and safety of the entire electronic system. To comprehensively evaluate the pros and cons of an AC/DC converter, it is necessary to consider the following key performance dimensions.

1. Electrical performance parameters

This is a hard indicator to measure the basic functions of the converter.

efficiency

Definition: The ratio of output power to input power (η = Pout / Pin × 100) is an important indicator to measure the loss during energy conversion.

Importance: High efficiency means lower energy loss (shown as heat), resulting in smaller temperature rise, higher reliability, more compact heat dissipation design and lower operating costs. Currently, the full-load efficiency of high-quality converters generally exceeds 90% and must meet various global energy efficiency standards (such as DoE Level VI, CoC Tier 2).

​Power factor

Definition: Measures the effective utilization rate of the converter on the power grid. The lower the power factor, the more ineffective current the converter draws from the grid, causing pollution to the grid.

Importance: In order to reduce harmonic interference to the power grid, regulations mandate that equipment above a certain power must be equipped with a power factor correction circuit. Converters with active PFC can usually increase the power factor to above 0.95 or even close to 1.

Ripple and noise

Definition: The high-frequency AC clutter component superimposed on the output DC voltage. Ripple is mainly caused by internal switching actions, while noise comes from external interference.

Importance: This is a key indicator of the "purity" of the output power supply. Excessive ripple noise will interfere with sensitive analog circuits (such as sensors and audio equipment), causing digital circuits to malfunction. This parameter is usually measured in millivolts peak-to-peak (mVpp), with lower values ​​being better.

Linear adjustment rate

Definition: Under constant load conditions, the percentage change of the output voltage as the input voltage changes within the specified range. It reflects the converter's ability to withstand grid fluctuations.

Importance: The lower the regulation rate, the more stable the output of the converter is when the grid voltage is unstable.

Load regulation rate

Definition: When the input voltage is constant, the percentage of the output voltage changes as the load current changes from no load to full load. It reflects the converter's ability to cope with load changes.

Importance: The lower the regulation rate, it means that the converter can maintain the stability of the output voltage regardless of whether the load is light or heavy.

Dynamic response

Definition: When the load current suddenly changes suddenly (such as from light load to heavy load, or vice versa), the time required for the output voltage to return to the normal range after deviating from the stable value and the very large deviation voltage.

Importance: For loads with extremely fast changes in dynamic power consumption, such as CPUs and FPGAs, excellent dynamic response is the key to ensuring system stability and no downtime.

Start time & hold time

Start-up time: The time required from the input power supply to the output voltage establishing and stabilizing at the rated value.

Holding time: When the input power is disconnected, the time the output voltage can remain within the rated range. This provides a valuable time window for system backup power supply (such as UPS) switching.

2. Reliability and environmental performance parameters

This determines whether the converter can work stably for a long time in a specific environment.

mean time between failures

Definition: The average normal working life of a converter predicted based on a statistical model, usually in hours.

Importance: MTBF is the core indicator for measuring product reliability. The MTBF of industrial-grade and communication-grade power supplies is usually much higher than that of consumer-grade products, reaching hundreds of thousands or even millions of hours.

​Operating temperature range

Definition: The ambient temperature range in which the converter can ensure normal operation of all performance parameters.

Importance: Industrial applications typically require a wide temperature range from -40°C to +85°C or even wider. Derating at high temperatures (i.e. reducing the rated output power) is a common practice and must be considered when purchasing.

Isolation voltage

Definition: The high AC or DC voltage that can be withstood between the input and the output (and between the input and the housing), usually above 3000VAC.

Importance: This is a crucial security indicator. The high isolation voltage provides an electrical barrier to protect personnel and equipment on the low-voltage side from the risk of electric shock on the high-voltage side, while enhancing the system's anti-interference capability.

3. Safety and Compliance Performance

This is the admission ticket for the product to enter the market.

Security certification

The converter has passed the mandatory safety certification of the target market, such as UL/cUL (North America), CE (Europe), CCC (China), TÜV (Germany), etc. These certifications ensure that products meet low safety standards in terms of electrical insulation, fire protection, and protection against electric shock.

Electromagnetic compatibility

Electromagnetic interference: The electromagnetic noise generated by the converter itself is lower than the standard limit (such as CISPR 32 / EN 55032 Class B).

Electromagnetic immunity: The converter can withstand external electromagnetic interference without failure, such as static electricity, surges, rapid pulse bursts, etc. (standards such as IEC/EN 61000-4 series).

4. Other key features

Protection function

The built-in comprehensive protection circuit is an important guarantee for reliability, including: over-current protection, over-voltage protection, short-circuit protection, and over-temperature protection. These features ensure that under abnormal conditions, the converter automatically shuts down to protect itself and the load.

Size and power density

In modern electronic equipment, space is extremely valuable. The higher the power density (unit: W/in³ or W/cm³), it means that more power can be provided in the same volume, which is an intuitive indicator of technological advancement.

Summarize

Evaluating the performance of an AC/DC converter is a comprehensive process. Don’t just look at the output voltage and power, but comprehensively examine its efficiency, stability (ripple, regulation rate), reliability (MTBF, operating temperature), safety (isolation, certification) and protection functions. Understanding the underlying meaning of these performance parameters will help you select the appropriate, reliable "power heart" for your application.