In modern electronic devices, the HDMI interface has become the standard for high-definition video and audio transmission. Within HDMI-related converters, docks, and display equipment, electrolytic capacitors serve as critical components, playing a vital role in circuit stability and signal quality .

These seemingly simple components, through their unique characteristics, ensure seamless transmission of high-definition video and audio signals, delivering a smooth visual experience to users .

01 Characteristics and Value of Electrolytic Capacitors

An electrolytic capacitor is a type of capacitor that uses an electrolyte as its dielectric. Compared to traditional air capacitors, it offers higher capacitance and lower equivalent series resistance (ESR) .

These properties make electrolytic capacitors particularly suitable for electronic circuits requiring large-capacity energy storage and efficient filtering .

In the microscopic world of electronic devices, the chip aluminum electrolytic capacitor is a dedicated "behind-the-scenes hero." Known for its large capacity, low cost, and wide applicability, it can operate over a relatively broad range of voltages and temperatures, adapting to various environmental conditions .

Electrolytic capacitors typically have polarity and consist of a plastic or metal casing, an anode plate, and a cathode plate. Their operation is based on the dielectric formed by the electrolyte between the two metal plates .

This special construction gives them excellent electrical properties, making them a preferred component in many electronic circuit designs .

02 Specific Applications of Electrolytic Capacitors in HDMI Equipment

In HDMI equipment, electrolytic capacitors primarily serve the following functions: storing electrical energy to provide stable voltage and current for the circuit; filtering to smooth current and reduce power supply noise; and providing instantaneous current to meet sudden power demands in the circuit .

Stable power supply and effective noise filtering are especially crucial for signal quality when the device processes high-definition video signals .

The power supply filtering circuit is one of the most important application scenarios for electrolytic capacitors. In interface conversion equipment like HDMI-to-VGA converters, electrolytic capacitors play a central role in the power supply filtering circuit .

For instance, the CS5213 chip, used in HDMI-to-VGA conversion solutions, requires a stable power supply to ensure quality signal conversion. At the input of such power circuits, it is common to connect 10-100μF electrolytic capacitors to filter out power supply noise and ensure stable circuit operation .

Regarding ensuring the stability of signal conversion circuits, electrolytic capacitors are also essential for signal synchronization and timing control. In HDMI signal conversion equipment, the integrity of vertical sync (VSYNC) and horizontal sync (HSYNC) signals must be ensured, and the stability of these sync signals heavily depends on the power supply quality .

By providing a stable operating voltage, electrolytic capacitors ensure timing accuracy during the signal conversion process .

03 Key Points for Selecting Electrolytic Capacitors in HDMI Equipment

The withstand voltage rating of electrolytic capacitors needs to be appropriately chosen according to the different operating voltage systems of the HDMI equipment. Generally, a 10V rated capacitor is selected for 3.3V systems; a 10V rated capacitor for 5V systems; a 25V rated capacitor for 12V systems; and a 50V rated capacitor for 24V systems .

This selection ensures sufficient margin over the working voltage, which can reduce internal resistance, lower leakage current, and increase lifespan .

Regarding capacitance selection, values from the 10, 22, 47 series are preferred. For aluminum electrolytic capacitors below 25V, larger value models such as 224, 105, and 475 should be avoided. Increasing capacitance leads to higher cost and larger size, along with increased charging current and longer charging time, necessitating a balanced choice .

Temperature and lifespan are another key consideration. Electrolytic capacitors used in HDMI equipment must be selected with a operating temperature rating of 105°C. This is because for every 10°C increase in the capacitor's operating temperature, its lifespan halves .

Given that temperatures can be high inside enclosed spaces like HDMI converters, selecting high-temperature capacitors can significantly extend the equipment's service life .

Equivalent Series Resistance (ESR) and high-frequency characteristics cannot be overlooked either. In switching power supplies and high-speed signal processing circuits, the Equivalent Series Resistance (ESR) is a key parameter for electrolytic capacitors .

Capacitors with low ESR can better absorb peak (ripple) currents during rapid switching, reducing energy loss and heat generation . For HDMI equipment processing high-frequency signals, low-ESR electrolytic capacitors should be selected, and even high-frequency, low-impedance electrolytic capacitors can be considered .

04 The Importance of Layout and Installation

During the PCB layout stage, electrolytic capacitors should be kept away from temperature-sensitive devices and high-heat components. Because electrolytic capacitors are sensitive to temperature, high temperatures can affect their performance and lifespan .

In HDMI equipment design, ensure that electrolytic capacitors maintain an appropriate distance from major heat-generating components (like conversion chips) or take necessary heat insulation measures .

When installing electrolytic capacitors, attention must be paid to polarity; the positive and negative terminals must be connected correctly. Before installation, confirm the positive and negative terminals of the electrolytic capacitor (usually the positive terminal has an arrow mark or a "+" sign) to avoid reverse connection, which could damage the capacitor or cause a short circuit .

Soldering time and temperature should be controlled, generally not exceeding 3 seconds and 260°C, to prevent the internal electrolyte from vaporizing .

In filter circuit design, a common practice is to place appropriate decoupling capacitors at various key locations on the printed circuit board. The power input terminal typically has a 10-100μF electrolytic capacitor connected across it, and each integrated circuit chip is equipped with a 0.01pF ceramic capacitor .

This combination can effectively suppress power supply noise and improve HDMI signal quality .

05 Development Trends and Alternative Solutions

Although electrolytic capacitors have advantages in capacity and cost, solid-state capacitors and tantalum capacitors are becoming alternative choices in some HDMI equipment with higher requirements for size and performance .

Solid-state capacitors use a solid medium, have a simpler and more compact structure, and feature lower ESR and longer service life. However, their higher cost and smaller capacitance range limit their application in some cost-sensitive HDMI devices .

With the continuous upgrading of HDMI standards (such as version 2.1 supporting higher resolutions and refresh rates), requirements for power quality and signal integrity are increasingly higher, and the demand for high-frequency, low-impedance electrolytic capacitors is also growing .

This type of capacitor, through improved materials and production processes, reduces impedance under high-frequency conditions and optimizes high-frequency performance .

In the future, with the popularization of high-resolution video content like 4K and 8K, and the support for higher refresh rates and dynamic HDR, the requirements for power stability and signal purity in HDMI equipment will become more stringent .

Electrolytic capacitor technology will also continue to develop to meet these growing demands .

With the continuous upgrading of HDMI standards, the requirements for power quality and signal integrity are increasing. From early versions supporting 1080p to the current HDMI 2.1 supporting 8K resolution, electrolytic capacitor technology is also constantly advancing .

In the future, with the popularization of high-resolution video content like 4K and 8K, and support for higher refresh rates and dynamic HDR, HDMI equipment will demand even stricter power stability and signal purity .

Electrolytic capacitor technology will continue to evolve to meet these growing demands .