Capacity and rated operating voltage

The capacity and withstand voltage marked on the aluminum electrolytic capacitor body are important

 parameters for selecting capacitors.

In practical capacitor selection, larger capacitors should be used for areas with fast current changes, but

 larger capacitors are not necessarily better. Firstly, the cost and volume of capacitors may increase. Additionally,

 larger capacitors result in higher charging currents and longer charging times. These are all factors to consider 

in practical application selection.

Rated operating voltage: The DC voltage that a capacitor can withstand when it operates reliably for a 

long time within the specified operating temperature range. In AC circuits, it is important to note that 

the applied AC voltage should not exceed the DC operating voltage of the capacitor. The commonly

 used working voltages for fixed capacitors are 6.3V, 10V, 16V, 25V, 50V, 63V, 100V, 250V, 400V, 500V, 

and 630V. The actual voltage that a capacitor needs to withstand in a circuit cannot exceed its withstand

 voltage value.

In the filtering circuit, the withstand voltage value of the capacitor should not be less than 1.42 times the

 effective AC value. Another issue to note is the working voltage capacity, which generally needs to be 

above 15%.

Allowing capacitors to have more margin in their rated voltage can reduce internal resistance, decrease

 leakage current, reduce loss angle, and increase lifespan. Although using 50V aluminum electrolytic

 capacitors with a working voltage of 48V will not cause problems in the short term, their lifespan may

 decrease over time.

Dielectric loss

The energy consumed by a capacitor under the action of an electric field is usually represented by the 

ratio of the loss power to the reactive power of the capacitor, that is, the tangent value of the loss angle.

 In the equivalent circuit of a capacitor, the ratio of the series equivalent resistance ESR to the capacitance

 1/ω C is called Tan δ, where ESR is calculated at 120Hz. Obviously, Tan δ increases with the increase of 

measurement frequency, and the loss angle increases with the decrease of measurement temperature. 

Capacitors with larger loss angles are not suitable for working at high frequencies. The dissipation factor 

(DF) exists in all capacitors, and sometimes the DF value is represented by the loss angle tan δ. The lower 

this parameter, the better. But the parameter for aluminum electrolytic capacitors is relatively high.

Whether the DF value is high or low is related to temperature, capacity, voltage, frequency, etc. for capacitors

 of the same brand and series; When the capacity is the same, the higher the withstand voltage, the lower

 the DF value. In addition, the higher the temperature, the higher the DF value, and the higher the frequency, 

the higher the DF value.

External dimensions

The external dimensions are related to weight and pin type. Singled is a radial lead type, screw is a locking

 screw type, and there are also surface mount aluminum electrolytic capacitors. As for weight, two capacitors

 with the same capacity and withstand voltage, but different brands, must have different weights when compared; 

And the external dimensions are more related to the shell planning. Generally speaking, capacitors with

 the same diameter and capacity can be replaced with capacitors with higher heights for those with lower

 heights. However, when replacing capacitors with lower heights for those with higher lengths, the issue 

of mechanism interference must be considered.

ESR

ESR equivalent series resistance and ESL equivalent series inductance are important parameters - the basis 

of capacitance. A capacitor with a small equivalent series resistance (ESR) and a relatively large external

 capacitor can effectively absorb the peak (ripple) current during rapid conversion. It is more cost-effective 

to use capacitors with high ESR in parallel. However, this requires a compromise between PCB area, number

 of components, and cost.

Ripple current and ripple voltage

Also known as ripple current and ripple voltage, it is actually ripple ripple evolution. The meaning is that 

capacitors can withstand ripple current/voltage values. Ripple voltage is equal to the product of ripple current 

and ESR.

When there is a ripple current, even if the ESR remains constant, the ripple voltage will increase exponentially. 

In other words, when there is a ripple voltage, the ripple current also follows, which is why capacitors are 

required to have lower ESR values. After adding ripple current, the equivalent series resistance (ESR) inside 

the capacitor causes heating, which affects the service life of the capacitor. Generally, ripple current is

 proportional to frequency, so ripple current is also relatively low at low frequencies.

The rated ripple current is a numerical value defined under operating temperature conditions. In practical 

applications, the ripple tolerance of capacitors is also related to their operating environment temperature

 and the temperature level of the capacitor itself. Specifications usually provide a list of ripple currents

 that capacitors of different temperature levels can withstand under specific temperature conditions. 

Even provide a detailed chart to help users quickly find the capacitance ripple allowed to achieve a certain

 expected service life under certain environmental temperature conditions.

Leakage current

The dielectric of capacitors has a significant hindering effect on direct current. However, due to the presence 

of electrolyte on the aluminum oxide film dielectric, a small current called leakage current is generated

 during the reformation of the oxide film and the application of voltage. Usually, the calculation formula

 for leakage current with increasing temperature and voltage is roughly: I=K × CV. The unit of leakage 

current I is μ A, and K is a constant. Generally speaking, the higher the capacitance of a capacitor, the 

greater the leakage current. From the formula, it can be inferred that the higher the rated voltage, the 

greater the leakage current. Therefore, reducing the operating voltage can also reduce the leakage 

current.

life

Firstly, it should be clarified that aluminum electrolytic capacitors are bound to break down, it's just a

 matter of time. There are many reasons that affect the lifespan of capacitors, such as overvoltage,

 reverse voltage, high temperature, rapid charging and discharging, etc. Under normal use, the impact 

is on temperature, because the higher the temperature, the faster the evaporation loss of electrolyte. 

It should be noted that the temperature here does not refer to the environment or surface temperature,

 but to the working temperature of the aluminum foil. Manufacturers usually label the lifespan and 

testing temperature of capacitors on the capacitor body.

As the working temperature of capacitors increases by 10 ℃, their lifespan is halved. Therefore, do not

 assume that aluminum electrolytic capacitors with a lifespan of 2000 hours are better than those with

 a lifespan of 1000 hours. Pay attention to the testing temperature for confirming the lifespan. Every 

manufacturer has calculation formulas for temperature and lifespan, and when designing capacitors, 

actual data should be referenced for calculation. It should be noted that in order to improve the lifespan

 of aluminum electrolytic capacitors, it is necessary to lower the operating temperature and keep them 

away from heat sources on the PCB. Secondly, consider using capacitors with higher operating 

temperatures, although the price may also be higher.

Resistance

At a specific frequency, the resistance that obstructs the passage of alternating current is called resistance. 

It is closely related to the capacitance and inductance values in the equivalent circuit of the capacitor, 

and is also related to ESR. The capacitance of a capacitor gradually decreases with increasing frequency 

in the low frequency range, and when the frequency continues to increase and reaches the mid frequency 

range, the capacitance drops to the ESR value. When the frequency reaches the high frequency range,

 the sensitivity becomes dominant, so the resistance increases with the increase of frequency.

The output filtering electrolytic capacitor in a switching power supply has a sawtooth voltage frequency

 of up to tens of kHz, even tens of MHz. At this time, capacitance is not its main indicator. The standard

 for measuring the quality of high-frequency aluminum electrolytic capacitors is the "resistance frequency" 

characteristic, which requires a low equivalent resistance within the operating frequency of the switching 

power supply and good filtering effect on high-frequency peak signals generated by semiconductor

 devices during operation.

About Us

Guangdong Fulong Electronic Technology Co., Ltd. is a private high-tech enterprise specializing in the research and development, manufacturing, and sales of aluminum electrolytic capacitors, certified by IATF16949，ISO9001, ISO14001, and ISO45001. The company has a building area of 17000 square meters and more than 50 automated production lines; The total investment is 50 million yuan (RMB), with more than 100 employees, including more than 20 engineering and technical, quality management, and production management personnel. The annual production of capacitors (4 * 5.4~16 * 21.5) is about 400 million pieces; Our products are mainly sold to domestic and international markets, and we strive to promote our company's products globally.

Jiangxi Fulong Electronic Technology Co., Ltd. is a wholly-owned subsidiary of Guangdong Fulong Electronic Technology Co., Ltd. established in Hukou County, Jiangxi Province with a total investment of 500 million yuan. It has 50 fully automated production lines and an annual output of approximately 1.2 billion capacitors (4 * 5.4~16 * 21.5).

Fulong Group has an international professional core technology research and development team for aluminum electrolytic capacitors and a global sales network. Rich experience in the design, research and development, and production management of aluminum electrolytic capacitors. The R&D team follows the technical design theory of aluminum electrolytic capacitors, complies with international and domestic legal and regulatory requirements (RoHs), and adheres to the highest international quality standards

Fulong Group has high-quality and stable raw material supply partners, and key raw materials (such as aluminum foil, electrolytic paper, etc.) are selected from well-known Japanese and Korean companies (KJCC KDKNKK, etc.), ensuring reliable and stable advantages in product quality, environmental protection, safety, and energy conservation.

Fulong Group has a group of highly qualified professional technicians and management personnel who can produce various series of sheet aluminum electrolysis products according to customer requirements. The products include high-frequency low impedance, low leakage, wide temperature, extremely low impedance, non-polar, ultra long life, medium high voltage long life, high reliability and other new types of special requirements for surface mount products; At the same time, the company's products can withstand a soldering temperature of 260 ℃, meeting the lead-free reflow soldering technology required for SMT in the whole machine factory. All technical indicators of the products have reached or exceeded the international level of similar products.

While strengthening management and expanding operational scale, Fulong Group is also committed to improving its competitiveness and customer satisfaction, continuously and steadily increasing customer and social trust, continuously meeting market demand, further optimizing environmental management and expanding social contributions, and developing together with the electronics industry.

Guangdong Follon Electronic Technology Co., Ltd.

Jiangxi Follon Electronic Technology Co., Ltd.

Address: Building 3, South District, Haishan Science and Technology Park, Hukou County, Jiujiang City, Jiangxi Province

www.follon.com

Professional manufacturer of high-quality surface mount electrolytic capacitors