vishay - engnote

8/12/2019 vishay - engnote

1/7

Document Number: 34098 For technical questions, contact: [email protected] www.vishay.comRevision: 10-Aug-06 183

Engineering Note ILB, ILBB, IMC, ISC, IFCVishay Dale

Circuit Simulation of Surface Mount Inductorsand Impedance Beads

INTRODUCTIONWith the advent of higher component densities, smallercomponents, and reduced design to market times, many oftodays complex circuits are designed using a computer andcircuit simulation software rather actual physical breadboarding.

Inductors can be one of the most difficult passivecomponents to accurately simulate, due to their inherentparasitic capacitive and resistive elements. These parasiticelements are the result of the resistance and turn-to-turncapacitance of the current conductor, which will affect thecharacteristic impedance of the inductor, particularly athigher frequencies. Figure 1 illustrates the equivalent circuitmodel for a real inductor with parasitic elements.

SIMULATING THE PERFORMANCE OF ANINDUCTORIn many computer based circuit simulators, if a singleelement inductor is placed in the circuit, it will be representedas an ideal inductor. This may be acceptable if the simulationis at a frequency well below the series resonant frequency(SRF) of the inductor, as the impedance curve for the ideal

and the real inductors are identical over frequency until apoint that is about 20 % of the inductors SRF. At this point,the impedance curves diverge due to the effects of theparasitic elements.However, the accuracy of the ideal inductor model will beginto increase beyond 20 % of the inductors SRF.

Figure 2 is a graph of the impedance versus frequencycharacteristics of a real and ideal inductor.

Most inductors can be represented with an acceptabledegree of accuracy by one of the circuits shown in Figure 1.Circuit A typically represents an inductor that uses amagnetic core material such as ferrite or powdered iron.Circuit B will accurately represent most nonmagnetic coreinductors commonly referred to as air cores. If theequivalent circuit values of the parasitic capacitance andresistance are known along with the effective inductance, theinductor model can be inserted in the circuit simulator andprovide an accurate representation of the inductors trueperformance in the A circuit.

Vishay Dale has generated the equivalent circuit values formany of its surface mount product lines. A table illustratingthe equivalent circuit values for each of the current VishayDale product lines follows this discussion.

LIMITATIONS OF INDUCTOR MODELSMost inductors are used well below their series resonantfrequency (SRF) and these basic, three element inductormodels will be very accurate under these simulationconditions. The SRF of the inductor occurs when theinductivereactance (X L) is equal to the capacitive reactance(XC) of the conductor. The impedance of the inductor is at its

maximum and would be infinite if there were no core loss orif the resistance of the conductor were zero. Above the SRF,the X C exceeds X L and the inductor behaves like a capacitor.As the frequency increases above the SRF point, theinductor will go through several more resonant phases as aresult of secondary parasitic elements which require a morecomplex equivalent circuit. For this reason, the typical usefulrange for the three element inductor models is the SRF of theinductor plus about 25 %.

Figure 1. Equivalent Circuit for a Real Inductor

C R L CR

Circuit A Circuit B

L

Figure 2. Impedance/Frequency Curves of Real and Ideal 10 H Inductor

I m p e d a n c e

100 000

10 000

1000

1001 10 100

Frequency (MHz)

Ideal

SRF

Approx. 20 % SRF Real


2/7

www.vishay.com For technical questions, contact: [email protected] Document Number: 34098184 Revision: 10-Aug-06

Engineering Note ILB, ILBB, IMC, ISC, IFCVishay Dale Circuit Simulation of Surface Mount Inductors and Impedance Beads

IMC-0402EQUIVALENT CIRCUIT DATA

NOMINAL INDUCTANCE (nH) CIRCUIT RESISTANCE ( ) CAPACITANCE (pF) INDUCTANCE (nH)1.2

1.51.82.22.73.33.94.75.66.88.2

10.012.018.0

33.039.047.056.0

B

BBBBBBBBBBBBB

BBBB

75.790

50.56869.25472.76279.35787.17486.272

123.660143.730171.930230.000213.970312.950554.440

792.6501.0591.8321.987

2.12680

1.487301.320500.916370.820010.669230.571380.476810.382000.319750.283770.237230.191870.13639

0.083670.076280.060900.05267

0.896

1.2541.4692.1152.3562.9293.4524.1505.2556.3767.3298.904

11.17516.818

30.76935.93345.30054.122


NOMINAL INDUCTANCE (nH) CIRCUIT RESISTANCE (m ) CAPACITANCE (pF) INDUCTANCE (nH)1.51.8

2.22.73.33.94.75.66.88.2

10.012.015.018.022.0

27.033.039.047.056.068.082.0

100.0

BB

BBBBBBBBBBBBB

BBBBBBBB

0.03190.0485

0.05570.05540.03740.05410.08340.11970.12090.12560.18060.21730.28120.31400.3322

0.40090.52730.58090.72270.91171.09481.43471.5531

0.00000.0000

0.00000.01250.01180.02320.03620.04390.04860.05150.05550.06200.06300.06470.0698

0.06830.07400.06940.07230.06670.07170.06840.0709

1.341.65

1.982.523.153.684.405.466.547.829.64

11.5514.6417.4521.26

25.9831.9537.2945.3053.7063.1976.6293.26


3/7

Engineering Note ILB, ILBB, IMC, ISC, IFCCircuit Simulation of Surface Mount Inductors and Impedance Beads Vishay Dale


IMC-0805-01EQUIVALENT CIRCUIT DATA

NOMINAL INDUCTANCE (nH) CIRCUIT RESISTANCE () CAPACITANCE (pF) INDUCTANCE (

3.94.75.66.88.21012151822273339

47566882

100120150180220270330390470560680820

1000

BBBBBBBBBBBBB

BBBBBBBBBAAAAAAAA

0.08840.09580.10530.12970.14720.14680.17490.18610.21940.24200.26380.28140.3282

0.34320.40230.43560.48800.59680.72351.16471.24141.398317.7k16.4k12.6k10.5k10.9k12.1k13.5k12.5k

0.00750.00610.03250.03200.03980.14450.05980.08360.06980.08370.09210.10460.0924

0.09750.09270.09360.15030.09680.19940.12950.16980.17190.48120.56370.87141.57011.24881.36621.19621.4749

4.34.65.55.28.1

11.212.616.418.822.427.433.439.0

45.355.767.979.894.497.7

132.9150.2194.2230.6274.2331.9425.7491.0592.1737.5859.1


NOMINAL INDUCTANCE (H) CIRCUIT RESISTANCE ( ) CAPACITANCE (pF) INDUCTANCE (H)0.0100.012

0.0150.0180.0220.0270.0330.0390.0470.0560.0680.082

BB

BBBBBBBBBB

89.79 m107.98 m

119.35 m138.90 m135.92 m172.43 m218.71 m209.12 m215.71 m308.05 m224.86 m359.50 m

0.09840.0965

0.12850.13900.18270.22580.18760.24400.28820.32510.33690.2936

6.83 n9.09 n

11.09 n14.62 n18.48 n22.37 n30.59 n35.42 n37.57 n46.38 n54.42 n63.2 n


4/7




NOMINAL INDUCTANCE (H) CIRCUIT RESISTANCE ( ) CAPACITANCE (pF) INDUCTANCE (H)0.1000.1200.1500.1800.2200.2700.3300.3900.4700.5600.6800.820

1.0

1.21.51.82.22.73.33.94.75.66.85.2

10.0

BBBBBAAAAAAAA

AAAAAAAAAAAA

353.36 m363.80 m229.68 m312.54 m269.10 m

5.98 k4.11 k4.59 k7.48 k9.09 k

10.66 k11.24 k14.21 k

13.73 k15.51 k18.89 k20.98 k25.90 k24.65 k27.80 k26.43 k35.52 k38.26 k37.93 k46.21 k

0.37090.50190.60200.63530.78140.64740.68690.70500.79290.95630.87640.70701.2100

0.99001.58001.43001.12000.98001.52001.69001.41001.34001.57001.35001.5200

80.52 n103.4 n

139.55 n159.31 n205.23 n253.82 n309.87 n375.18 n439.72 n523.33 n646.61 n751.05 n

0.99

1.15 1.46 1.72 2.11 2.66 3.16 3.67 4.5

5.28 6.32 7.52 9.43

IMC-1210-100EQUIVALENT CIRCUIT DATA

NOMINAL INDUCTANCE (H) CIRCUIT RESISTANCE ( ) CAPACITANCE (pF) INDUCTANCE (H)0.0100.0120.0150.0180.0220.0270.0330.0390.0470.0560.0680.0820.1000.100.120.150.180.220.27

BBBBBBBBBBBBBAAAAAA

64.188.7

130.7143.7200.2156.7273.4197.6212.7277.6314.1325.6412.811.4613.6913.6918.4528.1445.62

0.13570.14630.17460.19260.18920.22270.15970.29760.26300.32890.29580.24830.34690.53510.46970.47570.52310.45440.4926

9.9 n11.8 n14.6 n17.4 n21.3 n29.2 n38.4 n34.0 n44.2 n48.1 n61.8 n84.9 n84.9 n

0.0935 0.1177 0.1424 0.1623 0.2012 0.2408


5/7




NOMINAL INDUCTANCE (H) CIRCUIT RESISTANCE (k ) CAPACITANCE (pF) INDUCTANCE (H)0.330.390.470.560.680.821.001.201.501.802.20

AAAAAAAAAAA

28.0029.2429.4741.3632.5132.7612.4012.3314.9218.8923.51

0.53650.51270.54270.44980.47920.46741.69201.67401.69301.44101.6220

0.29570.34290.45080.51040.60670.74120.95131.16401.40201.73702.1300

ILBB-0603EQUIVALENT CIRCUIT DATA

NOMINAL IMPEDANCE CIRCUIT RESISTANCE ( ) CAPACITANCE (pF) INDUCTANCE (H)40606880

120220300450600750

1000

AAAAAAAAAAA

6580

1001181573154205456908101.1k

0.9000.9000.9001.0001.2000.9000.8000.8000.8000.9000.658

0.09520.15330.17790.19930.33560.60370.79541.11861.45312.01822.4001

ILBB-0805EQUIVALENT CIRCUIT DATA

NOMINAL IMPEDANCE CIRCUIT RESISTANCE ( ) CAPACITANCE (pF) INDUCTANCE (H)11326090

120150300400600

100015002000

AAAAAAAAAAAA

185082

125165208350510636975

16002500

0.900.850.701.001.001.001.000.901.201.001.000.90

0.02730.10530.21140.28360.29690.44370.86211.32741.34542.75734.74127.4365


6/7



ILB-1206EQUIVALENT CIRCUIT DATA

NOMINAL IMPEDANCE CIRCUIT RESISTANCE ( ) CAPACITANCE (pF) INDUCTANCE (H)

1926503170

120150300500600

AAAAAAAAAA

2737753795

150180330485610

0.90.80.41.00.21.50.91.82.12.0

63.51 n75.00 n

109.60 n73.34 n

174.12 n352.33 n492.76 n

1.05 1.69 2.49

ISC-1210 0.10 H - 1 HEQUIVALENT CIRCUIT DATA

NOMINAL INDUCTANCE CIRCUIT RESISTANCE ( ) CAPACITANCE (pF) INDUCTANCE (H)0.0100.0120.0150.0180.0220.0270.0330.0390.047

0.0560.0680.0820.1000.1200.1500.1800.2200.2700.3300.3900.4700.560

0.6800.8201.000

AAAAAAAAA

AAAAAAAAAAAAA

AAA

1.041.211.802.502.353.003.073.634.39

5.474.74

10.127.502.393.373.203.994.274.753.007.496.19

7.796.85

10.40

0.10030.10510.21780.24870.24340.22790.19830.44370.2873

0.42330.32590.35060.41300.55360.53820.68480.65730.62290.63770.91181.10160.9598

0.73701.01871.3400

0.007410.007820.012840.015640.018890.024660.031880.034270.03947

0.044780.060280.076960.082880.120070.147000.164200.221310.256780.316730.390580.440610.50199

0.625920.804020.98740

IFC-0805/0603

Contact Factory for Current Data


7/7



FREQUENTLY ASKED QUESTIONSWhy is the equivalent circuit inductance less than thenominal value of the inductor? For instance, the equivalentcircuit inductance listed for an IMC-1210 0.82 H inductor isonly 0.74 H.

The effective inductance of a component can be adverselyaffected by the parasitic elements. Capacitance cancels outsome of the inductive reactance and reduces the effectiveinductance of the device. Throughout a family of inductors,wire size, core size, core material and number of turns will bevaried to achieve the proper inductance. The most efficientinductors (with smallest parasitic element) have the lowestnumber of turns, the largest wire and the optimum coredimensions.

Since it is not economically feasible to have ideal core andwire sizes for each inductance value in a series, some valueswill have more significant parasitic elements that affect theperformance of the inductor. For example, one core and wire

size may be used for as many as 5 adjacent values in aninductor series. The number of turns is varied to achieve thehigher inductance values. An inductor with more turns willhave more inter-winding capacitance so the highest inductorwith the same core and wire size will typically be moreaffected by the winding capacitance than the lower values.

I would like to perform a Monte Carlo analysis that willexamine my circuit over the tolerance range of all mycomponents. How much can I expect the parasitic elementsto change due to manufacturing tolerances?

This is a tough question to answer.

Vishay Dale and other inductor manufacturers sell inductors

based on four major specifications:Inductance a percentage tolerance

Minimum Q at a specified frequency

Maximum DCR of the winding or conductor

Minimum SRF

In order to achieve these specifications, core size and material,wire size, and number of turns can be varied. Due tomanufacturing tolerances on all of the inductor components,wire size and/or number of turns may vary on the same valueacross production lots. Varying the wire size and/or turns willaffect the values of the parasitic components, however, thespecified L, Q, DCR, and SRF will always be in tolerance.Vishay Dale designs and manufactures inductors withrespect for the behavior of parasitic elements. Typically, thebasic tolerance of the purchased inductor (i.e., 10 H 10 %)can be applied to all the equivalent circuit elements in theinductor model with good success.

I use S parameters in my circuit simulator. Are theyavailable for Vishay Dale inductors?

Because of the complexity of distributing S parameters forall the inductor series, we have opted not to provide S

parameters for these products. As an alternative, most circuitsimulation programs will generate S parameters for asimulated circuit. The equivalent circuit elements for theVishay Dale inductors can be entered as a separate circuitinto the simulator which can in turn generate a table or file ofS parameters for the inductor model.

I am interested in simulating the performance of a VishayDale inductor that is not on the charts contained within thisapplication note. How can I get equivalent circuit informationfor this inductor?

Vishay Dale will be adding equivalent circuit information forother products as demand requires. If there is a specificinductor you would like information on that has not been

published, we can normally supply this information withinone week of the request.

My circuit simulator already contains a library of inductivecomponents models from Vishay Dale and other vendor products. How do I know if these are accurate models?

Some component libraries contain models that have beenempirically generated from catalog specifications, and sothese models may not accurately depict productperformance. To have full confidence in your library ofinductive component models, we strongly suggest that youcontact the vendor of your circuit s imulator to determine thesource of the supplied inductor model data. All data includedhere in our Application Note has been generated by testingnormally processed product and represents the typicalperformance you can expect from the Vishay Dale product.

Documents

vishay - engnote