SPICE

Document 267
SPICE Model – MSS1278
This lumped-element (SPICE) model data simulates the
frequency-dependent behavior of Coilcraft power inductors within the frequency range shown in the accompanying table for each individual inductor.
The data represents de-embedded measurements, as
described below. Effects due to different customer circuit board traces, board materials, ground planes or
interactions with other components are not included and
can have a significant effect when comparing the simulation to measurements of the inductors using other
production verification instruments and fixtures.
The value of the frequency-dependent variable resistor
RVAR1 is calculated from:
RVAR1 = k1 *
• k1 is shown for each value in the accompanying table.
• f is the frequency in Hz
• RVAR1 is the resistance in Ohms
The value of the frequency-dependent variable resistor
RVAR2 is calculated from:
RVAR2 = k2 *
Lumped Element Modeling Method
• k2 is shown for each value in the accompanying table.
Measurements were made using a 50 Ohm impedance
analyzer. Fixture compensation was performed to remove fixture effects. No DC bias current was applied in
any of the measurements. The lumped element values
were determined by optimizing the simulation model to
an average of the measurements. This method results in
a model that represents as closely as possible the typical
frequency-dependent behavior of the component within
the model frequency range.
• f is the frequency in Hz
The equivalent lumped element model schematic is
shown below. Each model should be analyzed only at
the input and output ports. Conclusions based on individual lumped element values may be erroneous.
• k3, k4, and k5 are shown in the accompanying table.
• RVAR2 is the resistance in Ohms
Note: The log function in the following equation is the
natural logarithm, base e, not base 10.
The value of the frequency-dependent inductance LVAR
is calculated from:
LVAR = k3 − k4
* LOG (k5 * f)
• f is the frequency in Hz
• LVAR is the inductance in µH
• LOG is the natural LOG (base e)
Disclaimer
RVAR2
VAR
C
R2
RVAR1
VAR
R1
LVAR
Coilcraft makes every attempt to provide accurate measurement data and software, representative of our components, in a usable format. Coilcraft, however, disclaims
all warrants relating to the use of its data and software,
whether expressed or implied, including without limitation any implied warranties of merchantability or fitness
for a particular purpose. Coilcraft cannot and will not be
liable for any special, incidental, consequential, indirect
or similar damages occurring with the use of the data
and/or software.
Specifications subject to change without notice.
© Coilcraft, Inc. 2007
Document 267-1 Revised 08/03/07
Document 267
SPICE Model for Coilcraft MSS1278 Power Inductors
Part number
MSS1278-142
MSS1278-472
MSS1278-562
MSS1278-682
MSS1278-822
MSS1278-103
MSS1278-123
MSS1278-153
MSS1278-183
MSS1278-223
MSS1278-273
MSS1278-333
MSS1278-393
MSS1278-473
MSS1278-563
MSS1278-683
MSS1278-823
MSS1278-104
MSS1278-124
MSS1278-154
MSS1278-184
MSS1278-224
MSS1278-274
MSS1278-334
MSS1278-394
MSS1278-474
MSS1278-564
MSS1278-684
MSS1278-824
MSS1278-105
Frequency limit
of model (MHz)
Lower Upper
0.1
80
0.1
30
0.1
30
0.1
30
0.1
30
0.1
20
0.1
20
0.1
20
0.1
20
0.1
20
0.1
15
0.1
10
0.1
10
0.1
10
0.1
10
0.1
10
0.1
10
0.1
10
0.1
8
0.1
7
0.1
7
0.1
7
0.1
6
0.1
6
0.1
5
0.1
4
0.1
4
0.1
4
0.1
3
0.1
3
LVAR Coefficients
⏲)
R1 (⏲
13
14
13
13
16
17
19
16
16
18
22
24
20
19
33
32
22
23
38
36
40
38
42
36
36
58
75
10
40
90
⏲)
R2 (⏲
0.011
0.020
0.023
0.024
0.028
0.030
0.032
0.038
0.043
0.050
0.060
0.080
0.085
0.10
0.11
0.12
0.15
0.18
0.23
0.27
0.30
0.40
0.53
0.60
0.68
0.88
0.96
1.3
1.5
1.7
C (pF)
3.37
9.48
9.24
8.95
6.50
10.20
15.40
7.18
12.00
12.90
12.00
20.40
9.80
14.80
11.10
12.50
11.30
10.80
14.20
15.10
12.60
16.40
14.40
14.10
12.50
14.70
13.80
12.20
12.20
13.20
k1
7.90E-06
3.90E-05
7.20E-05
2.64E-04
9.11E-04
6.22E-04
6.20E-04
4.88E-04
7.80E-02
1.01E-03
1.27E-03
1.20E-03
1.76E-03
2.45E-03
3.17E-03
4.60E-03
4.08E-03
5.51E-03
5.24E-03
6.93E-03
9.56E-03
7.56E-03
6.98E-03
1.11E-02
1.19E-02
1.00E-02
1.42E-02
1.04E-02
8.80E-03
8.10E-03
k2
0.43
1.75
1.62
2.8
3.08
4.05
6.9
5.8
8.9
11.2
12
24
29
26
29
30
44
68
75
70
88
77
120
80
102
110
126
132
124
160
k3
1.4
4.7
5.6
6.8
8.2
10
12
15
18
22
27
33
39
47
56
68
82
100
120
150
180
220
270
330
390
470
560
680
820
1000
Specifications subject to change without notice.
k4
5.24E-03
0.061
0.067
0.144
0.131
0.230
0.288
0.273
0.415
0.480
0.672
0.611
0.739
1.10
1.46
2.14
2.18
2.64
2.64
3.76
5.20
4.36
4.00
6.55
7.42
7.45
6.60
5.10
6.76
7.12
k5
7.90E-06
9.80E-06
9.80E-06
9.80E-06
9.50E-06
9.75E-06
9.84E-06
9.80E-06
9.84E-06
9.85E-06
9.85E-06
9.97E-06
9.90E-06
9.92E-06
9.89E-06
9.89E-06
9.95E-06
9.98E-06
1.01E-05
1.02E-05
1.01E-05
1.05E-05
1.09E-05
1.07E-05
1.08E-05
1.16E-05
1.25E-05
1.49E-05
1.54E-05
2.00E-05
Document 267-33 Revised 11/05/04