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BCcomponents DATA SHEET Overload protection for telecommunication PTC thermistors 2000 Oct 10 Supersedes data of 17th May 1999 File under BCcomponents, BC02 BCcomponents Overload protection for telecommunication PTC thermistors FEATURES • Wide resistance range in telecom area 4... to 70 Ω • Fast protection against power contact faults PRIMARY PROTECTION (OPTIONAL) • Withstand high overload currents of up to 10 A • High voltage withstanding capabilities for the larger sized thermistors +θ PTC subscriber lines SECONDARY PROTECTION +θ PTC voltage clamp • Good tracking over a wide temperature range for all matched or binned types +θ +θ PTC • UL1434 approved types available (XGPU2) SUBSCRIBER LOOP INTERFACE CIRCUIT (SLIC) OR TRANSFORMER CCB913 MDF • Excellent stability over extended time • All telecom PTCs are coated with a high temperature silicon lacquer (UL94V0) to protect them from any harsh environments and to improve their lifetime. Fig.1 Typical telephone line equipment showing where PTC thermistors can be used for overcurrent protection. APPLICATIONS • Main Distribution Frame (MDF) • Central Office Switching (C.O.) • Subscriber Terminal Equipment (T.E.) • Set-top box (S.B.). DESCRIPTION Advanced developments in telephony equipment in recent years have radically altered the protection requirements for both exchange and subscriber equipment. The BC Components range of Positive Temperature Coefficient (PTC) thermistors includes devices specially designed to provide overcurrent protection. 2000 Oct 10 2 BCcomponents Overload protection for telecommunication PTC thermistors OVERCURRENT PROTECTION OF TELECOMMUNICATION LINES mains could occur for up to several hours. To handle this power, the resistance/temperature characteristic of the thermistor must have a very steep slope and the ceramic must be extremely homogeneous. The PTC thermistor must protect the telephone line circuit against overcurrent which may be caused by the following examples: In case of overcurrent due to short-term induction of alternating voltages, currents of several AMPs with voltages as high as 650 VRMS can be present for several seconds • Surges due to lightning strikes on or near to the line plant. • Short-term induction of alternating voltages from adjacent power lines or railway systems, usually caused when these lines or systems develop faults. For standard high voltage applications, resistance values from 25 to 50 Ω are available. However, ISDN networks which carry high-frequency sound and vision, need lower line impedance. • Direct contact between telephone lines and power lines. To provide good protection under such conditions a PTC thermistor is connected in series with each line, usually as secondary protection; see Fig.1. However, even with primary line protection (usually a gas discharge tube), the PTC thermistor must fulfil severe requirements. Telecommunication designers are therefore demanding high voltage thermistors with much lower R25 values, which places even greater demands on the manufacture of PTC thermistors. For these applications PTC thermistors which have a R25 value of 10 Ω with voltages in the 300 to 600 VRMS range are available. Surge pulses of up to 2 kV can occur and in order to withstand short-term power induction the PTC thermistor must withstand high voltages. If the line has primary protection a 220 V to 300 V PTC thermistor is adequate. Without primary protection, however, a 600 V PTC device is necessary. BCcomponents manufacturers a range of PTC thermistors (see Table 2) covering both requirements. In a typical telephone line application, two PTC thermistors are used, one each for the tip and ring (or A and B) wire together with their series resistors. For good line balance it is important that the thermistor and resistor pairs are matched. On request, BCcomponents can supply matched or binned PTC thermistors with R25 values matched to as close as 0.5 Ω. In the case of direct contact between the telephone line and a power line, the PTC thermistor must withstand very high inrush power at normal mains voltage. Under such conditions, overload currents of up to 10 A on a 230 V 2000 Oct 10 3 BCcomponents Overload protection for telecommunication PTC thermistors MECHANICAL DATA Table 1 Specific physical dimensions and packaging for catalogue numbers as listed; see Fig.2 D MAX. (mm) T MAX. (mm) H2 (mm) L1 (mm) H3 MAX. (mm) PACKAGING(1)(2) CATALOGUE NUMBER 2322 ... ..... 7.0 4.0 3.5 ±0.5 − 11.0 taped H0 = 16 mm 661 91066 8.5 5.0 1.5 to 3.0 − 11.5 taped H0 = 16 mm 661 93048 7.0 4.0 2.0 ±0.5 − 9.8 taped H0 = 18 mm 661 93147 6.7 4.0 1.5 to 3.0 − 10.0 taped H0 = 18 mm 661 93025 7.0 5.0 1.5 to 3 − 10.0 taped H0 = 16 mm 661 93037 8.3 4.0 1.5 to 3.0 − 11.0 taped H0 = 18 mm 661 93043(3) 6.8 4.3 1.5 to 3.0 − 10.1 taped H0 = 16 mm 661 93142 11 4.5 4 ±1.0 − 15.5 taped H0 = 16 mm 662 93081 11 4.5 4 ±1.0 − 15.5 taped H0 = 16 mm 6.7 1.8 − − − disc on tray 661 93118 661 93148 662 93074(3) 7.0 4.0 2.0 ±0.5 − 9.8 taped H0 = 18 mm 13.6 6.0 4 ±1.0 20 ±4.0 18.6 bulk 663 93025(3) 8.3 5.0 1.5 ±0.5 20 ±3.0 10.3 bulk 661 93078 7.0 4.0 2.5 ±0.5 − 10.0 taped H0 = 16 mm 661 93121 8.5 4.0 2.5 ±0.5 4.1 ±0.5 11.5 bulk 661 93124 8.5 4.0 2.5 ±0.5 − 11.5 taped H0 = 16 mm 661 93146 8.5 4.0 2.5 ±0.5 4.1 ±0.5 11.5 bulk 661 93135 8.0 5.0 2.5 ±0.5 − 11.0 taped H0 = 16 mm 661 93056 661 93139 8.5 4.0 2 ±0.5 − 11.0 taped H0 = 16 mm 10.5 5.0 2 ±0.5 − 12.6 taped H0 = 16 mm 662 93129 13 5.5 4 ±1.0 20 min. 18.0 bulk 662 93114 13 5.5 4 ±1.0 20 min. 18.0 bulk 662 93131 Notes 1. Taped in accordance with “IEC 60286-2” ; standard packaging: 1500 units/reel. 2. Naked disc ceramic for substrate mounting, available on request. 3. Insulated version is also available. 2000 Oct 10 4 BCcomponents Overload protection for telecommunication PTC thermistors T D D H3 H2 F L1 d CCB914 For dimensions see Table 1. Lead pitch F = 5 mm +0.6/−0.1. Lead thickness d = 0.6 mm ±10%. Fig.2 Component outline. 2000 Oct 10 5 T V MAX. (V) Electrical data for catalogue numbers as listed NON-TRIP CURRENT Int (mA) at T (°C) RESISTANCE R25 (Ω ) TOL (%) MATCHED PAIRS TRIP CURRENT It (mA) at T (°C) MAX. TRIP TIME at 25 °C tt (s) at It (mA) APPLICATION AREA(1) COMPATIBILITY CATALOGUE NUMBER 2322 ... ..... 6 100 85 65 4 ±25 0.5 Ω 280 25 4.0 1000 MDF; ISDN − 661 91066 220 70 70 25 ±20 1Ω 200 25 2.5 1000 C.O. K20/21 661 93048 230 100 70 10 ±20 1Ω 250 25 3 1000 MDF; ISDN K20/21 661 93147 245 60 70 70 +10/−15 no 180 25 60 245 75 70 33 ±20 ±5% 150 10 245 70 70 25 ±15 1Ω 200 25 245 65 85 25 ±20 2% 200 25 3.40 245 140 55 16 ±20 no 270 25 8 245 140 55 10 ±20 no 270 25 8 250 100 40 20 +10/−20 1Ω 220 25 250 70 70 25 ±20 1Ω 175 220 C.O. − 661 93025 1000 C.O. − 661 93037 400 C.O. K20/21; FTCSE I31-24 661 93043 650 C.O. K20/21 661 93142 1000 T.E. K20/21; FTCSE I31-21 662 93081 1000 T.E. K20/21; FTCSE I31-21 662 93074 1 1 000 MDF − 661 93118 25 1.3 1 000 MDF; C.O. K20/21 661 93148 663 93025 1.2 20 100 70 10 ±20 no 450 0 0.30 8 000 T.E. K20/21 135 95 8 ±25 0.5 Ω 400 25 6 1000 MDF; ISDN K20/21 661 93078 300 100 70 16 ±25 no 250 25 2.0 1000 MDF; T.E. K20/21 661 93121 350 100 70 10 ±20 no 270 25 4.0 1000 T.E.; S.B. K20/21 661 93124 350 100 70 10 ±20 1Ω 270 25 4.0 1000 C.O. K20/21 661 93146 600 50 70 50 ±20 1Ω 140 25 1 1000 C.O. K20/21 661 93135 600 70 70 35 ±20 3Ω 600 0 3 1000 C.O. K20/21 661 93056 600 70 70 25 ±20 2% 170 25 4 700 C.o. K20/21 661 93139 600 70 70 25 ±20 2% 170 25 8 700 C.O. K20/21 662 93129 600 175 25 10 ±20 0.5 Ω 400 25 7 1000 C.O. UL1459/GR1089 662 93114(2) 600 175 25 10 ±20 no 400 25 7 1000 T.E.; S.B. UL1459/GR1089 662 93131(2) Notes 1. MDF: Main Distribution Frame; C.O.: Central Office Switching; T.E.: Subscriber Terminal Equipment; S.B.: Set-top Box. 2. UL 1434 approved types. Overload protection for telecommunication 250 285 BCcomponents Table 2 PTC thermistors 2000 Oct 10 ELECTRICAL DATA