How to calculate the inductance of inductors in series or in parallel?

The calculation of in ductance value is similar to resistance calculation if the inductors are used in series or parallel.

1. The total inductance will be increased when an inductor is used in series, and the total inductance is the sum of all inductors. (L = L1 + L2 + L3 +...)

2. The total inductance will be decreased when an inductor is used in parallel, but the current will be higher. The total current is the sum of the currents in each inductor, it can be used in circuits with a higher current. L=1/(1/L1+1/L2+1/L3+1/L4+……).

​What’s the normal tolerance for an inductor?

Power inductor manufacturer usually define the tolerance with specific letters in inductor naming,such as the following tolerances of power inductors, J: 5% ; K: 10% ; M: 20% ; N: 30%

Will power inductor selection affect the efficiency of power supply?

Selecting a right inductor will effect efficiency of  power supply. However, the power needs to be converted into specific parameters such as input voltage, output voltage, switching frequency, ripple current, output current. 

Does an inductor have the rated voltage?

A power inductor doesn’t have defined the rated voltage because most of the inductors are used in the low-voltage DC-DC convector. For any applications in which inductor high-voltage is required, please contact CODACA.

​Where can I find the weight for each of CODACA parts?

The weight of a CODACA part is typically specified on the datasheet.

Where can I find tape-and-reel specifications for all CODACA’s products?

Tape-and-reel information of all CODACA’s products can be found in products’ datasheet with the dimensions  at CODACA’s website.

How much space should be allowed between components to counter interactions?

It's difficult for CODACA to recommend a specific minimum spacing between inductors. Electromagnetic fields created by inductors generally interact only with metallic surfaces or other inductors in close proximity. However, the extent of interaction between inductors depends on the current (frequency, waveform shape and magnitude ), the orientation to each other, and the distance between inductors. (Remind: Orienting the axes of inductors perpendicular to each other, rather than parallel, to get a minimum interaction.) 

Can you provide a reflow soldering profile for your parts?

Yes. CODACA provides a reflow soldering profile in each datasheet. The optimal reflow profile for a circuit board assembly depends on soldering materials, soldering amount, flux, temperature limits of each soldered component, heat transfer characteristics of the circuit board and component materials, and the layout of all components.

What's the benefit of using shielded parts?

Magnetic shielding is to reduce the amount of magnetic flux generated outside an inductor, in terms of reducing the likelihood of radiating energy to nearby components or circuit board traces causing EMI. Whether a shield is necessary or not depends on the proximity of other components and how field interactions would affect the circuit's performance. Field interactions are challenging to prototyping while measurement of the final circuit design is recommended. In addition to reducing radiated fields, magnetic shielding typically helps to achieve more inductance per given size of an inductor.

What is shelf life of CODACA's parts?

For 30°C / 85% relative humidity maximum, CODACA’s parts are good indefinitely ,based on MSL=1,CODACA’s parts are good for one year in packaging.

Is CODACA able to provide UL,CSA,TUV,CE and other safety certificates?

These safety standards are most commonly appl to complete electronic assemblies, such as power supplies, computers, modems, and televisions, but not specifically to CODACA’s inductorsIn most cases, CODACA’s  are usually evaluated as parts for finished products built by its customers. Inductors are not required to provide above certificated individually.

What are power ratings for CODACA's inductors which are not specified on datasheets?

RMS current ratings are power ratings for CODACA’s inductors, derived by applying DC or low frequency AC currentto measure the resultant temperature rise. This allows for an accurate determination of temperature rise vs. RMS current, which can easily be related to temperature rise vs. power loss: Power Loss = Irms2 × DCR.

Meanwhile,CODACA’s inductor losses include skin effect, high-frequency core loss and proximity effect, which can add to the temperature rise. While these losses are applicational  dependents and should be verified in situations, CODACA offers design tools for predicting frequency effects. To estimate core loss, conductor loss, and temperature rise of ours power inductors, use the Power Inductor Loss Comparison.

Whydo you provide no polarity markings on part of paroducts?

Inductors do not have a functional polarity, which make they work equally in either direction. polarity is not very important in the vast majority of end-use circuits. It has been reported that some inductors perform better when mounted in one particular orientation, due to interaction with nearby components or ground plane conductors. Any asymmetrical performance is very much related to a function of the application, especially board layout. For any applications in which inductor polarity is critical, please contact CODACA.

What are the advantages of the EQ-core high current inductors if comparied with toroid inductors?

There are many kinds of toroid inductors with different characteristics. We could compare a high current power inductor with a toroid inductor  same kind of core material in the same application.

Here are findings through the comparison:

1. The utilization rate of winding window area of the toroid-core inductor is lower than the EQ -core high current power inductor. For the same electrical performance, the volume of high current power inductor with EQ cores will be relatively smaller than toroid inductor.

2. The high power toroid-core inductor can’t realize automatic assembly because the wire is too thick and can only be wound by hand. 

3. The high current inductor with EQ-core is designed with flat wire, the effective cross-section is bigger than the round wire, the DRC is lower thant that of the toroid core inductor, so it can withstand higher current.

4. The AE value of the high current inductor with EQ-core is higher than that of the toroid- core inductor. The high current inductor has better DC bias ability than the toroid-core inductor.

5. The toroid-core inductor coil is exposed, which has leak magnetic flux to affect other component in PCB when power supply is working. While, the coil of high current power inductor with EQ-core is wrapped inside with excellent anti-interference ability.

Why are some inductors coated? What's the function of coating?

1.For high current power indutors, the magnetic-core with coating is a method of insolation improvement to increase the withstand voltage of products. 

2.For molding power chokes, coating can protect the magnetic powder and prevent the product from rusting.

How should engineers suppress the noise in power supply applications?

There is no method to 100% eliminating the noise. Instead, it can be suppressed or weakened. The source of noise is usually caused by a mechanical resonance in the component that is excited by the electrical conditions of the circuit, known as magnetostriction, and does not indicate a defect in the part. It depends on the application conditions and is not always possible to eliminate by changes to the inductor.

Changing the switching frequency is the best way to eliminate the noise. Applying a dampening material (electronic-grade encapsulant, potting compound, etc.) may decrease the produced sound level the increased mass of a larger component may dampen or shift the resonance to a different frequency.

What are factors cause the temperature rise during the operation of an inductor?

1. The current margin of a power inductor is insufficient. The current over the power inductor in applications is higher than the rated current of inductor which will casue high temperature rise.

2.The alternating current or ripple current in the circuit is too high, and the magnetic core loss is serious, resulting in heating.

3.The application frequency is very high, but engineers won’t select the right core and wire during the inductor design.

How to reduce power inductor losses in the high frequency and high ripple current applications?

Base on the high frequency and high ripple current applications, the core losses and the AC losses of copper wires should be considered in the design of power inductors. Such as ferrite core and low permeability powder core are suitable for high-frequency applications. Besides, the influence of skin effects should be considered, flat wire or litz wire design can also be used to reduce AC losses.