# What is the SPICE model and its purpose?

SPICE model is a kind of circuit model of a component, which is described by the text-file format and suitable for the SPICE simulation software.

SPICE model can be used for predicting the electrical characteristics of the component by mathematics in different circumstances. The electrical characteristics which can accord with the characteristics of the real component can be got based on the working principles and mathematical equations of ideal components in the SPICE model.

# what are S parameters and their purposes?

S parameters are also called the scattering parameters, which are used for evaluating the performance of DUT reflecting and transmitting signals. The S parameters which contain the amplitude and phase information of the signals are defined as the ratio of two plural.

S parameters usually expressed as: S (output, input)

Output: output port number of DUT

Input: input port number of DUT

For example, S21 means the ratio of the DUT’s output signal in port 2 and the input signal in port 1, and the output signal and input signal are plurals.

First of all, at the high frequency range, S parameters can be got easily and S parameters can correlate with many other familiar parameters such as gain, loss, and reflection coefficient and so on;

Second, the H, Y, or Z parameters can be calculated using the S parameters;

Finally, the S parameters are suitable for all kinds of simulation software.

# How to select the power inductor?

The following items should be noted when selecting power inductors at design stage.

1. The applying fields should be considered firstly. Power inductors are widely used in the DC-DC conversion circuits, power supply circuits, audio filtering circuits and so on.

2. For DC-DC conversion circuits, the power inductor selected should be determined by the frequency of the applying signal. It is required that the self-resonance frequency should be larger than that of the signal.

3. The inductance selected should fit the design of the circuit. For example, in the DC-DC conversion circuits, power inductor is used to store energy and suppress the ripper. Usually a larger inductance indicates the stronger storage and filtering effect, but at the same time the larger inductance can increase the RDC of the inductor which will decrease energy efficiency and can’t be used for large current application.

4. The power inductor should be selected according to the current of the loop. Two kinds of current should be taken into account. When select the power inductor, the smaller is considered as rated current.

5. The size of power inductor should be selected according to the land pattern and space of the application.

# What is the advantage of sunlord’s SWPA series inductors compared with conventional shielded power inductor?

Sunlord’s SWPA series wire wound power inductors apply unique compact structure and show the following advantages:

1. Sleeveless square-core winding makes full use of core space and thickens lead wire inside inductor to achieve lowest possible DC resistance

2. To minimize heat generation and maximize efficient use of battery power

3. 40% Higher current rating than conventional inductors of equal size, takes up less PCB real estate

4. Metallization on ferrite core results in excellent shock resistance and damage-free durability

5. Magnetic-resin shielded construction reduces buzz noise to ultra-low levels

6. Closed magnetic circuit design reduces leakage flux and Electro Magnetic Interference (EMI)

7. For the same output, compared with conventional process, Sunlord’s innovative automatic production process saves 80% labor force and 50% manufacture space.

8. Products have higher quality and reliability as automatic process and can minimize differences among operators.

# What are the main electrical parameters of power inductor?

The main electrical parameters of power inductor include L, DCR, saturation current (Isat), heating rating current (Irms), and SRF.

L: L is the nominal inductance of the inductor. Due to the distributing capacitance, the value of L shows frequency dependency. The tolerance of the inductance is commonly classified into M (±20%) and N（±30%）grades.

DCR: DC resistance is the direct-current resistance of the wire between the electrodes.

Saturation Current (Isat): The inductance will decrease under continual current. The Saturation

Current (Isat) is also called DC Superimposition Current and defined as the current at which the inductance drops by 30%.

Heating Rating Current (Irms): The component body temperature will increase under continual current. The Heat Rating Current is defined as the current that causes the component body temperature rise 40℃ from 20℃ ambient.

SRF (Self-resonant Frequency): The SRF is defined as the frequency at which the inductor reaches the resonant state due to the interaction of the inductance and stray capacitance.

# What are differences between SDCL0603C series and SDCL0603Q series?

SDCL0603C series and SDCL0603Q series are both high frequency ceramic inductors and manufactured by multilayer technology. SDCL0603Q series applies unique inner electrode design to achieve high Q value which is more than 30% comparing with SDCL0603C series and are suitable for RF circuit demanding high sensitivity.

# What are the difference between SDCL series, SDHL series and HQ series of Sunlord inductors?

Sunlord has several types of multilayer ceramic inductors, SDCL, SDHL and HQ series. They are manufactured by different designs and have different performances in inductance, DC resistance, self-resonant frequency and Q value. The following examples are for 1005 size. SDCL series are ordinary ceramic inductors with inductance ranging from 1nH (the inductance below 1nH is also available) to 270nH, high Q and high SRF, and are widely used in RF circuits.

SDHL series are designed in vertical electrical structure and thus have special high SRF value. For the same inductance, SDHL’s SRF is at least 50% higher than SDCL’s. If applied in GHz band, SDHL series is preferred and recommended for inductance of 10nH and more.

HQ series are developed for ultra high Q value to substitute wire wound inductors. For the same inductance, HQ series provide higher Q value and higher SRF than SDCL and SDHL series, even compatible with wire wound ceramic inductors. Therefore, HQ series can be used to replace wire wound ceramic inductors for high sensitivity use of RF circuit.

# What are the differences between ordinary ferrite inductors, multilayer chip inductor for choke and multilayer chip power inductors ？

Sunlord has three types of multilayer chip ferrite inductors, SDFL ordinary inductors, MCL choke inductors, and MPL power inductors.

(1) DC superimposition characteristics: MPL inductors have the best performance while SDFL inductors have the worse.

(2) DC Resistance: With the same inductance, MPL inductors have the smallest DCR and SDFL inductors have the biggest one.

(3) Rated Current (Ir): The definition is different. For MPL inductors, Ir is based on temperature rising and the value is over 1A. For MCL inductors, Ir is based on inductance change by 50% and the value is about several hundred mA. For SDFL inductors, Ir is based on inductance change by 5% and the value is about several to dozens of mA.

(4) Structural design: On one hand, MCL inductors and MPL inductors need wide and thick electrodes to achieve small RDC, on the other hand, MCL inductors and MPL inductors need to optimize electrode pattern to achieve uniform magnetic field distribution and thus get good DC superimposition characteristics.

(5) Applications: SDFL inductors are commonly used for resonant or noise suppression at dozens of MHz signals. MCL inductors are used for power line choke and isolation between digital and analog lines. MPL inductors are used for energy storage and reducing ripple current in DC-DC conversion circuit.

# I need chip inductors of 1608 size of 220nH inductance, but I found SDFL1608L.R22 and SDCL1608CR22 two part numbers. Which one is better for me?

Sunlord’s inductors include two series, SDFL ferrite inductors and SDCL ceramic inductors. The main difference between the two series sees as the following:

(1) Application: SDFL series are used at low frequencies commonly below 100MHz; and SDCL series are used at high frequencies from several hundred to several thousand MHz.

(2) Measuring frequency: SDFL series were measured at 50MHz, 25MHz, 10MHz, 4MHz and so on according to the inductance, and SDCL series were measured at 100MHz and 50MHz.

(3) Q value: SDFL series’ Q value is commonly over 40 at measuring frequency and would decrease as the frequency increases, and SDCL series’ Q value is nearly 10 at measuring frequency and would increase as the frequency increases.

(4) DC resistance: SDFL series’ RDC was smaller than that of SDCL series.

(5) Rated current: the definition is different. It is defined as L changes for SDFL series and temperature rising for SDCL series.