PDF PBL38710-1 Data sheet ( Hoja de datos )

Número de pieza	PBL38710-1
Descripción	Subscriber Line Interface Circuit
Fabricantes	Ericsson
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No Preview Available ! February 1999 PBL 387 10/1 Subscriber Line Interface Circuit Description The PBL 387 10/1 ring SLIC (Subscriber Line Interface Circuit) is a bipolar integrated circuit in 90 V technology which replaces the conventional transformer based analog line interface and ringrelay in FITL, WLL, ISDN-TA and other telecommunications equipment with a modern, compact solid state design. Not only is required PCB area reduced, but less component weight and height result as well. The PBL 387 10/1 has been optimized for low cost and to require only a minimum of external components. The PBL 387 10/1 constant-current feed system, programmable to max 40 mA of line current, can operate with battery supply voltages down to -21 V to reduce line card power dissipation. The SLIC incorporates loop current, ground key and ring trip detection functions. Two-to four-wire and four- to two-wire voice frequency (vf) signal conversion is accomplished by the SLIC in conjunction with either a conventional CODEC/filter or with a programmable CODEC/filter (e.g. SLAC, SiCoFi, Combo II). The programmable line terminating impedance could be complex or real to fit every market. The PBL 387 10/1 package is 28-pin PLCC. RDR TIPX HPR HPT RINGX VCC VEE Two-wire Interface Ring Trip Detector Ground Key Detector Line Feed Controller and Longitudinal Signal Suppression Battery switch Input Decoder and Control VBAT2 VBAT C1 C2 HB E1 DET RDC RSG Key Features · Ring SLIC eliminates ring relay and conventional ring-generator · Supports sine wave and trapezoidal ringing · -85 V battery feed for high voltage ring signal · On chip automatic battery switch · Programmable battery feed characteristics · Battery supply voltage as low as -21 V for power efficient line card designs · Low on-hook power dissipation, 50 mW @-24 V battery · Loop current, ring trip and ground key detection functions · Programmable loop current detector threshold · Programmable ring trip detector threshold · Hybrid function with all types of CODEC/filter devices · Programmable line terminating impedance, complex or real · On-hook transmission · Tip-ring open circuit state for subscriber loop power denial AGND BGND Off-hook Detector VF Signal Transmission RD VTX 3871P0B/1L RSN Ringing Control VR 28-pin PLCC Figure 1. Block diagram. 1 http://www.Datasheet4U.com/ 1 page PBL 387 10/1 Parameter Frequency response Two-wire to four-wire, g2-4 Ref fig Conditions Min Typ Max Unit 6 0.3 kHz < f < 3.4 kHz relative to 0 dBm, 1.0 kHz. ERX = 0 V -0.2 0.2 dB Four-wire to two-wire, g 4-2 6 0.3 kHz < f < 3.4 kHz relative to 0 dBm, 1.0 kHz. EL = 0 V -0.2 0.2 dB Four-wire to four-wire, g4-4 6 0.3 kHz < f < 3.4 kHz relative to 0 dBm, 1.0 kHz. EL = 0 V -0.2 0.2 dB Insertion loss Two-wire to four-wire, G2-4 6 0 dBm, 1.0 kHz, Note 4 G2-4 = 20 · Log VTX , ERX = 0 VTR -0.2 0.2 dB Four-wire to two-wire, G 4-2 6 Gain tracking Two-wire to four-wire Four-wire to two-wire 6 6 Noise Idle channel noise at two-wire (TIPX-RINGX) or four-wire (VTX) output Harmonic distortion Two-wire to four-wire Four-wire to two-wire 0 dBm, 1.0 kHz, Notes 4, 5 V G4-2 = 20 · Log TR , EL = 0 ERX Ref. -10 dBm, 1.0 kHz, Note 7 -40 dBm to +3 dBm -55 dBm to -40 dBm Ref. -10 dBm, 1.0 kHz, Note 8 -40 dBm to +3 dBm -55 dBm to -40 dBm C-message weighting Psophometrical weighting Note 6 0 dBm, 1.0 kHz test signal 0.3 kHz < f < 3.4 kHz -0.2 0.2 dB -0.1 0.1 dB -0.2 0.2 dB -0.1 0.1 dB -0.2 0.2 dB 10 12 dBrnC -80 -78 dBmp -60 dB -60 dB Figure 6. Frequency response, insertion loss, gain tracking. ω1C<< RL, RL= 600 Ω RT = 600 kΩ, RRX = 300 kΩ RL EL C VTR ILDC TIPX VTX PBL 387 10/1 RINGX RSN RT RRX E RX VTX 5 http://www.Datasheet4U.com/ 5 Page PBL 387 10/1 VTX PBL 387 10/1 ZT RSN RTX ZB Z RX Figure 10. Hybrid funktion. RFB VT Combination CODEC/Filter VRX RF TIP TIPX RING CHP RF HPT HPR RINGX VT + VLo RHP / 2 1/2 1/2 RHP / 2 VR + VLo I Lo VT + VR 2 + VLo + + 1 - V LoRef I Lo VLO R Lo 20K I Lo / 1000 PBL 387 10/1 Figure 11. Longitudinal impedance. Longitudinal Impedance A feed back loop counteracts longitudi- nal voltages at the two-wire port by injecting longitudinal currents in opposing phase. Thus longitudinal disturbances will appear as longitudinal currents and the TIPX and RINGX terminals will experience very small longitudinal voltage excursions, leaving metallic volta- ges well within the SLIC common mode range.This is accomplished by comparing the instantaneous two-wire longitudinal voltage to an internal longitudinal reference voltage, VLoRef . VLoRef = VBat2 2 = VT + 2 VR where VT and VR are tip and ring gro- und referenced voltages without any longitudinal component. As shown below the SLIC appears as 20 Ω per wire to longitudinal disturbances. It should be noted that longitudinal currents may exceed the dc loop current without distur- bing the vf transmission. Refer to figure 11. Circuit analysis yields: VLo RLo = ILo 1000 which reduces to RLoT = RLoR = VLo /ILo =20kΩ/1000 = 20Ω where: RLo = 20 kΩ RLoT = RLoR = longitudinal resistance/wire VLo = longitudinal voltage at TIPX,RINGX ILo = longitudinal current Capacitors CTC and CRC The capacitors designated CTC and CRC in figure 12, connected between TIPX and ground as well as between RINGX and ground, are recommended as an addition to the overvoltage protection network. Very fast transients, appearing on tip and ring, may pass by the active components in the overvoltage protection network before they have had time to activate and could damage the SLIC. CTC and CRC short such very fast transients to ground. CTC and CRC also work as RFI- filters in conjunction with suitable series impedances (i.e. resistances, inductances). Resistors RF1 and RF2 may be sufficient, but series inductances can be added to form a second order filter. The recommended value for CTC and CRC is 2200 pF. Higher capacitance values may be used, but care must be taken to prevent degradation of either longitudinal balance or return loss. CTC and CRC contribute to a metallic impedance of 1/(π·f·CTC) = 1/(π·f·CRC), a TIPX to ground impedance of 1/(2·π·f·CTC) and a RINGX to ground impedance of 1/(2·π·f·CRC). AC - DC Separation Capacitor, CHP The high pass filter capacitor connected between terminals HPT and HPR provides the separation between circuits sensing tip-ring dc conditions and circuits processing ac signals. A CHP value of 10 nF will position the low end frequency response 3dB break point at 48 Hz (f3dB) according to f3dB= 1/(2·π·RHP·CHP) where RHP ≈ 330 kΩ. Battery Feed The block diagram in figure 13 shows the PBL 38710/1 battery feed system and figure 14 illustrates the battery feed characteristics in the active state. For a tip to ring dc voltage VTR less than the saturation guard reference voltage ,VSGRef, the SLIC emulates a constant current feed characteristic in the active state. The constant current is inde- pendent of the actual battery voltage, VBat2, connected to the SLIC. With the tip to ring DC voltage VTR exceeding VSGRef, the feed characteristic changes to a nearly-constant voltage feed. This is to prevent the tip and ring drive amplifiers from distorting the AC signal as might have otherwise occurred due to insufficent voltage margin between VTR and VBat2. Thus the SLIC 11 http://www.Datasheet4U.com/ 11 Page

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