Document 158 SPICE Model – 1812CS This lumped-element (SPICE) model data simulates the frequency-dependent behavior of Coilcraft RF surface mount inductors from 1 MHz to the upper frequency limit shown in the accompanying table. The equivalent lumped element model schematic is shown below. The element values R1, R2, C, and L are listed for each component value. The value of the frequency-dependent variable resistor RVAR relates to the skin effect and is calculated from: RVAR = k * • • k is shown for each value in the accompanying table. f is the frequency in Hz 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 typical production verification instruments and fixtures. Each model should only be analyzed at the input and output ports. Individual elements of the model are not determined by parameter measurement. The elements are determined by the overall performance of the lumped element model compared to the measurements taken of the component. Typically, the Self-Resonant Frequency (SRF) of the component model will be higher than the measurement of the component mounted on a circuit board. The parasitic reactive elements of a circuit board or fixture will effectively lower the circuit resonant frequency, especially for very small inductance values. Since data sheet specifications are based on typical production measurements, and the SPICE models are based on de-embedded measurements as described below, the model results may be different from the data sheet specifications. Lumped Element Modeling Method The measurements were made over a brass ground plane with each component centered over an air gap, as illustrated in Figure 1. The gap width for each size component is given in Table 1. The test pads were 30 mil Table 1. Test Gap Size 0302 0402,0403 0603 0805 1008 1206 1812 Gap Width (inch / mm) 0.017 / 0.432 0.017 / 0.432 0.026 / 0.660 0.040 / 1.016 0.060 / 1.524 0.080 / 2.032 0.120 / 3.048 (50 Ohm) wide traces of tinned gold over 25 mil thick alumina, and were not included in the gap. The TRL* calibration plane is also illustrated in Figure 1. Pad Pad Brass ground plane Calibration plane Figure 1. Test Setup The lumped element values were determined by matching 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 up to a frequency just above the self-resonant frequency of the model. The lumped element models were used to generate our 2-port S-parameters and therefore give identical results. The S-parameters are available on our web site at http://www.coilcraft.com/models.cfm. Disclaimer 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. 2009 Air gap Document 158-1 Revised 03/16/09 Document 158 SPICE Model for Coilcraft 1812CS Chip Inductors R1 ⏲) Part number (⏲ 1812CS-102 58 1812CS-122 63 1812CS-152 72 1812CS-182 72 1812CS-222 80 1812CS-272 68 1812CS-332 81 1812CS-392 121 1812CS-472 85 1812CS-562 198 R2 ⏲) (⏲ 1.2 1.2 1.6 2.0 2.2 3.2 3.8 5.0 5.4 5.7 C (pF) L (µH) 0.143 0.148 0.135 0.127 0.150 0.123 0.120 0.118 0.122 0.165 1.005 1.220 1.520 1.820 2.250 2.700 3.330 3.950 4.775 5.700 k 4.23E-04 5.28E-04 5.76E-04 6.21E-04 8.60E-04 9.80E-04 1.12E-03 1.12E-03 1.80E-03 2.01E-03 Upper limit (MHz) 470 420 390 370 310 310 260 240 220 190 R1 ⏲) Part number (⏲ 1812CS-682 1812CS-822 1812CS-103 1812CS-123 1812CS-153 1812CS-183 1812CS-223 1812CS-273 1812CS-333 203 212 244 244 288 286 318 338 266 R2 ⏲) (⏲ 6.6 7.0 7.7 8.7 9.6 10.5 11.5 12.5 13.5 Specifications subject to change without notice. © Coilcraft, Inc. 2009 C (pF) L µH) 0.166 0.202 0.210 0.241 0.312 0.370 0.342 0.540 0.885 6.800 8.200 10.000 12.000 15.000 18.000 22.000 26.890 32.750 k 2.58E-03 3.30E-03 4.98E-03 3.65E-03 4.91E-03 7.21E-03 8.70E-03 1.12E-02 1.77E-02 Upper limit (MHz) 170 140 130 110 90 70 70 50 40 Document 158-17 Revised 06/04/04