Sidactor Protection Thyristor Products Page 44 SIDACtor Protection Thyristor Products

SIDACtor Protection Thyristors 2017 Littelfuse, Inc. Specifications are subject to change without notice. Revised: 02/23/17 TIA-968-A applies to all terminal equipment connected to the Public Switched Telephone Network (PSTN) in the USA, and holds the "rule of law" by congressional order. The purpose of TIA-968-B is to provide a set of uniform standards to protect the telephone network from any damage or interference caused by the connection of terminal equipment. This standard includes environmental simulations such as vibration tests, temperature and humidity cycling, drop tests and tests for hazardous voltages and currents, as well as tests for signal power levels, line balance, on-hook impedance, and billing protection. All these standards must be met before and after the environmental tests are applied. TIA-968-B compliant equipment must undergo an overvoltage test that includes a Type A and Type B Metallic Voltage Surge and a Type A and Type B Longitudinal Voltage Surge. These surges are part of the environmental simulation, and although a provision does allow the EUT to reach an open circuit failure mode during the Type A tests, failures must: 1. Arise from an intentional design that will cause the phone to be either disconnected from the public network or repaired rapidly 2. Be designed so that it is substantially apparent to the end user that the terminal equipment is not operable [A common example of an acceptable failure would be an open circuit due to an open connection on either Tip or Ring.] For Type B surges, equipment protection circuitry is not allowed to fail. The EUT must be designed to withstand Type B surges and continue to function in all operational states. Overvoltage Test The Type A and Type B Metallic Voltage Surges are applied in both the positive and negative polarity across Tip and Ring during all operational states (on-hook, off-hook, ringing, and so on). The Type A metallic surge can be as high as 880 V, 115A peak surge while the Type B metallic surge can be as high as 1100 V, 27.5 A peak surge, as presented in Table 3.29. The repetition rate contained in TIA-968-B is 1 for each surge event. However, the companion test document TSB-31-D (Rationale and Measurement Guidelines for U.S. Network Protection )cites TIA-571-B (Electrical, Thermal, Mechanical Environmental Performance Requirements), which requires 4 surges for each Type A surge event and 8 surges for each Type B surge event. It also requires incremental testing from 100 V to the maximum output level in 100 V increments for Type A surges. Therefore, engineering consideration should be made for surge repetition rates greater than those specifically stated in TIA-968-B. Metallic Voltage Surge Table 3.29 TIA-968-B Voltage Surge Surge Type Peak Voltage volts Rise/Decay time s Peak current amps Rise/Decay time s Reps Metallic A 800 - 880 6-10/560-860 100 - 115 5-10/560-760 1 Longitudinal A 1500 - 1650 6-10 /160-260 200 - 230 5-10/160-210 1 Metallic B 1000 - 1100 92.7/720144 25 - 27.5 51.5/32064 1 Longitudinal B 1500 - 1650 92.7/720144 37.5 - 41.3 51.5/32064 1 Notes: For Type A surges, the EUT may pass either "operationally" or "non-operationally." For Type B surges, the EUT must pass "operationally." The peak current for the Type A longitudinal surge is the total available current from the surge generator. The peak current for the Type B longitudinal surge is the current supplied to each conductor. Longitudinal Voltage Surge The Type A and Type B Longitudinal Voltage Surges are applied in both positive and negative polarity during all operational states. "The Type A longitudinal surge can be as high as 1650 V, 230A peak surge while the Type B longitudinal surge can be as high as 1650 V, 41.3 A peak surge, as presented in Table 3.29. This longitudinal surge is applied to the EUT with tip and ring connected together and surged with respect to ground. The repetition rate contained in TIA-968-B is 1 for each surge event. However, the companion test document TSB-31-D (Rationale and Measurement Guidelines for U.S. Network Protection )cites TIA-571-B (Electrical, Thermal, Mechanical Environmental Performance Requirements), which requires 4 surges for each Type A surge event and 8 surges for each Type B surge event. It also requires incremental testing from 100 V to the maximum output level in 100 V increments for Type A surges. Therefore, engineering consideration should be made for surge repetition rates greater than those specifically stated in TIA- 968-B. Note : Type B surge requirements guarantee only a minimum level of surge protection. For long term reliability of terminal equipment, consideration should be given to complying with Type A surges operationally. Regulatory Requirements (continued)

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