TEST METHODS FOR PULSE 10BASE-T MODULES Application Note Scope This application note depicts PULSE’s test methodology for 10Base-T. Test methods are in compliance with the IEEE Std 802.3i-1993, which addresses both the 10Base-T chip as well as the 10Base-T module specifications. Module is defined as a single package component that includes various combinations of resistors, transformers, filters and common mode chokes. The combination of a Pulse 10Base-T module with a compliant 10Base-T chip will meet or exceed the IEEE Std 802.3i as well as enhance the ability to comply with FCC/VDE emissions. This application note will describe the test methods listed in the bulleted items below. ■ Hi Pot ■ Insertion Loss ■ Return Loss ■ Cross Talk ■ Common Mode Rejection Hi Pot Short all transformer pins on the primary or chip side together. An example would be pins 1 through 7 of the module shown in Figure 1. Also short the secondary or media side pins together, i.e. pins 8, 9, 13, and 14 in Figure 1. Apply 1500 volts RMS at 60 Hz for 60 seconds across pins 1 and 14. No voltage breakdown should occur. Insertion Loss Figure 1, on the next page, is a typical Insertion Loss Test Circuit. Pulse test fixtures include either a North Hills Transformer or a Pulse PE-65490 Transformer (North Hills Transformer equivalent). The purpose of these transformers is to convert a 50 Ω coax line to 100 Ω. The network analyzer sweeps the requested frequency range and displays the measured frequency response. To perform the Insertion Loss test: 1. Calibrate the network analyzer in the S21 mode by shorting pins 1 and 14 together and shorting pins 3 and 13 together. Do a thru calibration. 2. Place module in test fixture and measure the insertion loss from 1 MHz to 100 MHz. As seen in Figure 1 on the next page, some 10Base-T modules contain pre-equalization resistors. Actual measured insertion loss readings will vary with those resistor values. All of Pulse’s low pass filters, designed for 10Base-T applications, meet or exceed IEEE Std 802.3i. However, the pre-equalization resistors mask filter performance test results. 12220 WORLD TRADE DRIVE, SAN DIEGO, CALIFORNIA 92128 • TEL 619-674-8100 • FAX 619-674-8262 • http://www.pulseeng.com E110.A (5/97) TEST METHODS FOR PULSE 10BASE-T MODULES Application Note NORTH HILLS 0300BB OR EQUIVALENT RDM 1 TPR+ 14 3 TPR50 Ω RDP LP 2 100 Ω TPX2+ TPX1+ XFMR CMI 13 12 LP NORTH HILLS 0300BB OR EQUIVALENT 4 11 5 10 GND 100 Ω LP 6 7 XFMR CMI LP 50 Ω GND 9 TDP 8 TDM TPX2TPX1- PORT A HP3577 NETWORK ANALYZER OR EQUIVALENT PORT B Figure 1 Return Loss Nominal input impedance is 100 Ω; however, the IEEE 802.3i Standard calls for 96 Ω ±20%. The measured return loss shall be a minimum of 15 dB at impedance extremes. Return loss is an actual measurement of the mismatches in the module. If each element were a pure and precise 100 Ω, there would be no reflection or return; however, realistically, some mismatch does occur. In order to meet 15 dB at impedance extremes, a typical device should exhibit at least 20 dB at a nominal impedance of 100 Ω. Figure 2, on the next page, shows a typical test set-up for Return Loss. The following is the test procedure: 1. 2. 3. 4. 5. 6. Calibrate the network analyzer in the S11 mode. Short pins 13 and 14. Do a short. Leave pins 13 and 14 open. Do an open. Connect a 100 Ω resistor across pins 13 and 14. Do a load measure. Filter must be terminated in the appropriate test impedance with 100 Ω termination. Measure the Return Loss at 5 MHz to 10 MHz. 12220 WORLD TRADE DRIVE, SAN DIEGO, CALIFORNIA 92128 • TEL 619-674-8100 • FAX 619-674-8262 • http://www.pulseeng.com E110.A (5/97) TEST METHODS FOR PULSE 10BASE-T MODULES Application Note TPR+ CT TPRTPX2+ TPX1+ TPX1TPX2- 1 14 RDP 13 RDM LPF 2 XFMR CMI 3 12 LPF 4 NORTH HILLS 0300BB OR EQUIVALENT GND HP3577A NETWORK ANALYZER OR EQUIVALENT 11 100 Ω 5 10 LPF 6 XFMR CMI 7 LPF 50 Ω GND 9 TDP 8 TDM Figure 2 Crosstalk The Crosstalk test measures isolation between the transmit and receive channels. While a signal is applied to one channel, the network analyzer monitors the other channel. The maximum allowable crosstalk is 34.5 dB at 5 MHz and 30 dB at 10 MHz. To perform the Crosstalk test (see Figure 3): 1. Calibrate the network analyzer in the S21 mode. 2. Short pins 3-5 and 1-6 and do a thru calibration. 3. Measure the crosstalk between the two channels over the range of 5 MHz to 10 MHz. PORT A 50 Ω 100 Ω TPR+ 1 2 TPR- HP3577 NETWORK ANALYZER OR EQUIVALENT NORTH HILLS 0300BB OR EQUIVALENT TPX2+ 50 Ω 3 XFMR CMI RDP 13 RDM 12 LPF 4 TPX1+ 5 TPX1- 6 TPX2- 14 LPF 7 100 Ω GND 11 10 LPF XFMR CMI LPF GND 9 TDP 8 TDM 100 Ω 100 Ω PORT B Figure 3 12220 WORLD TRADE DRIVE, SAN DIEGO, CALIFORNIA 92128 • TEL 619-674-8100 • FAX 619-674-8262 • http://www.pulseeng.com E110.A (5/97) TEST METHODS FOR PULSE 10BASE-T MODULES Application Note Common Mode Rejection The Common to Common test circuit, in Figure 4 below, is the method used to measure Common Mode Rejection. This parameter is especially important in meeting FCC/VDE emission testing. Common mode currents on the transmission cable are a major source of EMI emissions. To perform the Common Mode Rejection test: 1. The equipment is first calibrated with a direct connection to a 50 Ω cable between the input and output of the waveform analyzer. Conduct a thru calibration. 2. The test fixture is then connected between the input and the output. Insert the device under test in the fixture. 3. The signal is then input into pins 4, 5, 6, and 7 which are shorted. Measure the output unbalance through R3 and R4. These resistors shoud be matched to within ±0.1%. 4. The test is repeated with pins 1, 2, and 3 shorted and connected to the input. The output imbalance is measured through R1 and R2 which are also matched to ±0.1%. 1 14 *R1 13 *R2 LPF 2 S1 3 XFMR CMI 4 5 * 50 Ω ± 0.1% R1=R2=R3=R4 11 10 LPF 6 XFMR CMI 50 Ω 7 S2 12 LPF LPF 9 *R3 8 *R4 50 Ω HP3577A NETWORK ANALYZER OR EQUIVALENT Figure 4 For More Information : Corporate Europe Asia 12220 World Trade Drive San Diego, CA 92128 Tel: 619 674 8100 FAX: 619 674 8262 http://www.pulseeng.com Quick-Facts: 619 674 9672 Millpool House Mill Lane, Godalming Surrey GU7 1EY U.K. Tel: 441 483 428 877 FAX: 441 483 416 011 P.O. Box 26-11, KEPZ 6 Central Sixth Road KEPZ, Kaohsiung Taiwan, R.O.C. Tel: 886 7 821 3141 FAX: 886 7 841 9707 Distributor Performance warranty of products offered on this data sheet is limited to the parameters specified. Data is subject to change without notice. Other brand and product names mentioned herein may be trademarks or registered trademarks of their respective owners. Printed on recycled paper. ©1997, Pulse Engineering, Inc. E110.A (5/97)