Protection for global telephony equipment Application Note AN005 for ESP TN, ESP TN/BX, ESP SL TN, ESP TNQ, ESP KT1, ESP TN/JP, ESP KT1/PTC, ESP K10T1, ESP K10T1/PTC, ESP TN/RJ11-*/6Protection for global telephony equipment This Application Note details advanced surge protection for Central Office and Customer Premise Equipment, covering global equipment specifications, exceeding the high speed requirements of VDSL2+. Any protector fitted to the telephone system should be invisible to the application, and not interfere with its normal operation. They should not clip or limit the voltages that occur in normal system operation, and the bandwidth should be sufficient for existing applications with headroom for system Graph 1: Maximum development in the foreseeable future. System In order to fully protect telephony Voltage systems, protection must be provided in all connection modes between lines, and between each line and earth, in both polarities. This is referred to as FULL MODE PROTECTION, and is essential to ensure continuous operation of sensitive or critical electronic equipment. Global systems requirements In order for these products to be applied anywhere in the world, we need to consider the most onerous voltage and frequency requirements that may exist on a global basis, and ensure that products Graph 2: are able to deal adequately with this. Maximum Considering Customer Premise Equipment, for System voltage, the highest requirement is currently Voltage with superimposed the FCC Part 68 B ringer. The B ringer ADSL Signal has a D.C. voltage of 56.5 V and a maximum A.C. ringing voltage of 150 V . This gives a RMS maximum voltage of 269 V, but because of possible wiring reversals, the protector should have a minimum working voltage of 269 V. The ADSL signal can be as high as 15 V (shown as a grey band), and this adds to the B ringer voltage, creating a peak value of 284 V. As before, we allow for 284 V to account for possible wiring reversals. AN005 page 2