In the compact electronic device known as a charger, electrolytic capacitors play an indispensable role. As core components of switching power supply products, electrolytic capacitors are responsible for the critical functions of filtering, energy storage, and voltage stabilization, directly impacting the charger's conversion efficiency, heat generation, and service life .

Especially with the rapid adoption of GaN (Gallium Nitride) fast-charging technology, the performance of electrolytic capacitors determines whether a charger can deliver higher power output within a smaller form factor .

01 The Pivotal Role of Electrolytic Capacitors in Chargers

After AC mains power is rectified by a bridge rectifier, it produces pulsating direct current, which contains significant ripple and must be smoothed before it can be safely used by devices. Electrolytic capacitors, with their high capacitance density and cost-effectiveness, are the ideal choice for efficient filtering .

In charger design, high-voltage electrolytic capacitors are typically placed on the primary side, directly connected to the rectifier circuit. For chargers designed for globally compatible voltage ranges, the peak voltage after rectification can exceed 300V. Therefore, capacitors with a rated voltage of 400V-450V are usually selected to ensure sufficient margin for grid fluctuations and surge currents .

The Equivalent Series Resistance (ESR) and ripple current rating are key parameters determining capacitor performance. Low ESR reduces energy loss, lowers capacitor temperature rise, thereby enhancing overall efficiency. A high ripple current rating prevents capacitor failure due to overheating, extending service life .

For fast-charging devices, electrolytic capacitors also help stabilize the rapid charging current, ensure quick discharge capability, and assist in promptly cutting off the charge during abnormal system operation to protect the device .

02 Capacitor Selection Strategies for Different Power Levels

Capacitor selection strategies vary significantly depending on the charger's power level. Ultra-slim fast chargers, with their extremely limited internal space, impose particularly stringent requirements on the high-voltage filter capacitors .

Taking a mainstream 65W ultra-slim GaN charger as an example, BPOWER Huiyue Guangdian's product uses 2x Wan Jingyuan 400V 47μF electrolytic capacitors in parallel, providing a total capacitance of 94μF. Conversely, various products from CUKTECH use Emerald 400V 27μF capacitors, also employing a dual parallel configuration .

More radically, the OPPO 50W Biscuit GaN fast charger completely abandons traditional electrolytic capacitors, innovatively using Murata high-voltage MLCCs for the filtering function .

For high-power PD3.1 fast chargers (140W, 240W, and higher), the voltage rating and capacitance requirements for the high-voltage filter capacitors increase accordingly. Teardown data indicates that in such chargers, the rated voltage for high-voltage electrolytic capacitors generally rises to the 420V-450V range, and capacitance options become more varied .

For instance, Ugreen's 300W 4C1A GaN charger uses Xin Zhongyuan 450V 100μF capacitors; Anker's 140W PD3.1 GaN charger selects Yongming 450V 120μF capacitors .

03 Innovative Capacitor Solutions from Jiangxi Fulong Electronics

Jiangxi Fulong Electronics Technology Co., Ltd., as a high-tech enterprise certified with IATF16949, ISO9001, ISO14001, and ISO45001, demonstrates strong competitiveness in the R&D, manufacturing, and sales of aluminum electrolytic capacitors .

The company boasts 70 fully automated production lines with an annual production capacity of approximately 1.2 billion capacitors. Its product range covers multiple sizes, offering various high-performance, miniaturized capacitor solutions for the fast-charging industry .

Fulong Electronics possesses an internationally professional core R&D team for aluminum electrolytic capacitor technology. It can produce various series of chip aluminum electrolytic capacitors according to client requirements, including products with special features like high frequency and low impedance, low leakage current, wide temperature range, very low impedance, non-polarity, and ultra-long life .

Aimed at the fast-charging market, Fulong Electronics has launched a series of innovative products. Among them, the FVM series of ultra-small chip aluminum electrolytic capacitors can be as small as 5mm*4.5mm, making them highly suitable for space-constrained high-end applications. Compared to imported brands, these products offer significant advantages in price and delivery time, meeting the demand for domestic substitution .

Fulong's capacitor products excel in voltage resistance, temperature characteristics, and service life. For example, its FVU series wide-temperature, long-life products can operate stably within a temperature range of -55°C to +105°C, while the FVD series high-voltage, long-life products can achieve a lifespan of 3,000 to 5,000 hours .

04 Key Parameters for Capacitor Selection

Selecting capacitors for charger design requires comprehensive consideration of several key parameters. The rated voltage should be 20%-30% higher than the peak operating voltage. For instance, a 400V rated capacitor should be selected for an application with an actual peak voltage of 320V .

Capacitance selection involves balancing filtering effectiveness with size and cost. Generally, higher capacitance offers better filtering but increases size and cost. A 65W PD fast charger typically requires a total capacitance of about 40-100μF .

ESR and Ripple Current are critical factors affecting efficiency. Low ESR capacitors reduce energy loss and improve efficiency. A high ripple current rating prevents capacitor failure due to overheating .

The temperature and lifespan characteristic is also crucial. Capacitor life follows the "10°C rule" – for every 10°C decrease in operating temperature, the lifespan approximately doubles. High-quality chargers typically select electrolytic capacitors rated for 105°C or even 125°C .

Additionally, small size, long life, high-temperature resistance, ability to withstand high-frequency, high ripple currents, and low impedance are important characteristics of specialized electrolytic capacitors for fast-charging power supplies .

05 Development Trends in Electrolytic Capacitor Technology

As fast-charging technology evolves towards higher power and smaller sizes, electrolytic capacitors face new challenges and opportunities. Miniaturization is one of the most prominent trends. For example, GP Gaopin Technology's new generation of aluminum electrolytic capacitors, adopting a 4.0 technology process, have seen a 20% volume reduction compared to the previous generation, achieving more compact dimensions .

Long Lifespan and High Reliability are another important direction. Fulong Electronics' FVU series wide-temperature, long-life products and FVD series high-voltage, long-life products are typical examples, maintaining stable performance under harsh operating conditions .

Integrated solutions are increasingly favored by the market. For instance, designs where planar transformers and the main board are combined into one require capacitors with superior electrical performance and a smaller footprint .

With the adoption of new standards like PD3.1, electrolytic capacitors need to adapt to higher power requirements and stricter efficiency standards, prompting manufacturers to innovate in material technology and structural design to meet growing market demands .

The adoption of the PD3.1 fast-charging standard and increasing output power are accelerating innovation in electrolytic capacitors. Domestic manufacturers like Jiangxi Fulong Electronics provide various high-performance, miniaturized capacitor solutions for the fast-charging industry through advanced production processes and product innovation .

Looking ahead, as fast-charging technology moves towards higher power density, electrolytic capacitors will continue to innovate along the paths of miniaturization, high efficiency, and extended lifespan, offering consumers a more portable, safer, and more efficient charging experience .