MH88612B Subscriber Line Interface Circuit (SLIC) Data Sheet Features DS5752 • • Transformerless 2-wire to 4-wire conversion Battery and ringing feed to line • • Off-hook and dial pulse detection. Ring ground over-current protection • • Adjustable constant current feed. Relay driver • • Power Denial Wide Operating Range MH88612BV-2 • • Intercoms Key Telephone Systems • Control Systems 20 Pin SIL Package 0°C to 70°C Description The SLIC provides a complete interface between a switching system and a subscriber loop. Functions provided include battery feed and ringing feed to the subscriber line, 2-Wire to 4-Wire hybrid interfacing, constant current feed and dial pulse detection. The device is fabricated using thick film hybrid technology in a 20-pin single in-line package. Line interface for: PABX May 2002 Ordering Information Applications • Issue 1 LPGND VBAT PD VCC VEE AGND Power Management TF TIP RING RF 2-Wire to 4-Wire Conversion Current and Voltage Sensing VR VX RV VRLY RC RD CD Over Current Protection Relay Drive Circuit Constant Current Feed Loop Supervision VREF CAP SHK Figure 1 - Block Diagram SEMICMF.019 1 MH88612B Data Sheet TF LPGND VR VREF VEE AGND PD VX TIP RING RF VCC RC RD RV VRLY CD VBAT CAP SHK 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 Figure 2 - Pin Connections Pin Description Pin # Name 1 TF 2 2 Description Tip Feed. Connects to external diode for protection LPGND Loop Ground. Is the system ground reference with respect to VBAT. Normally connected to AGND. 3 VR Voice Receive (input) is the 4 wire analog signal to the device. 4 VREF 5 VEE 6 AGND 7 PD Power Denial (Input). A logic high will isolate the battery voltage to Tip/Ring. 8 VX Voice Transmit (Output) is the 4-wire analog signal from the device. 9 TIP Connects to the “Tip” lead of the telephone line. 10 RING 11 RF 12 VCC 13 RC Relay Control (Input). Active high. 14 RD Open collector sinks current when RC is at logic high. 15 RV Ring Feed Voltage connects to pin 11 (RF) through a normally closed relay. 16 VRLY 17 CD 18 VBAT Negative Battery Feed Supply Voltage (-48V). 19 CAP Connects external capacitor to ground for ring trip. 20 SHK Switch Hook Detect (Output). Active high. Voltage Reference (Input) Constant current feed can be adjusted by the input voltage on VREF. This pin can also be grounded for normal 25mA loop current. Negative Power Supply Voltage (-5V). Analog Ground (0V). Connects to the “Ring” lead of the telephone line. Ring Feed (Input) is normally connected to Ring relay for negative battery feed voltage and ringing voltage input. Positive Power Supply Voltage (+5V). Relay voltage Supply (+5V). Clamping Diode. Connects to AGND SEMICMF.019 Data Sheet MH88612B Functional Description The SLIC performs a transformerless 2-wire to 4-wire conversion of the analog signal. The 2-wire circuit is the balanced line going to the subscriber loop, while the 4-wire circuit is the audio signal going to and from devices such as the voice codec or switching circuit. The SLIC also provides a switch hook (SHK) status output which goes high when the telephone is set off-hook. Constant Current Feed The SLIC employs a complex feedback circuit to supply a constant feed current to the line. This is done by sensing the sum of the voltages across the internal feed resistors and comparing it to an input reference voltage (VREF) that determines the constant feed current. If VREF (pin 4) is externally grounded, the constant current is set at 25mA. For a constant current setting between 18mA and 30mA, VREFcan be set between 8.75 Vdc and -6.35 Vdc. The relationship is defined by the equation: ILOOP = VBAT - VREF mA (+2 mA) 1.89 1.25 Switch Hook Detection When the DC current exceeds an internal threshold level, the switch hook (SHK) will go high. If the loop resistance is so high that VBAT can no longer supply the required amount of loop current as determined by constant current supply circuit, the output of the switch hook (SHK) will go low to indicate that the loop resistance is too high and the line is on hook. Ringing And Ring Trip Detection In Figure 3 a ringing signal (eg. 90 Vrms and -48Vdc) is applied to the line by disconnecting pin 15 (RV) from pin 11(RF), and connecting the ringing voltage at pin 11 (RF) by use of the relay K1. The SLIC can detect an off-hook condition during ringing but there is a large AC component which must be filtered out to give a true off-hook condition at SHK. A 1.0µF capacitor connected from pin 19 (CAP) to ground will provide adequate attenuation when ringing is applied. Once an off-hook condition has been detected a logic low should be applied to pin 13 (RC) which will deactivate the relay (K1) to disconnect the ringing voltage from pin 11 and reconnect to pin 15. At that time the SLIC will revert to constant current feed operation. For applications requiring Dial Pulse Detection the Capacitor connection to ground should be controlled such that the capacitor is only connected during ringing. During off-hook conditions (closed loop), the capacitor should be switched out. This can be performed using a transistor, relay or system drive output of a codec. Applying AGND to the Ring Trip Filter Control pin as shown in Figure 4 will switch in the filter, whilst removing AGND, (with the switch in a tri-state condition), will switch out the filter. For applications using DTMF signalling, the capacitor can be permanently connected to ground. SEMICMF.019 3 MH88612B Data Sheet Current Limit The Tip or Ring of the telephone line may accidentally be shorted to ground. In such a case, current will only flow through the feed resistor. This high current will be sensed and reduced by the current limit circuit to a lower value to protect the internal circuitry. Power Denial The power denial function is a feature of the MH88612B which allows for powering down of the subscriber loop. A logic high voltage applied to the power denial input effectively removes the battery voltage from the loop driver circuitry. The resulting ILOOP is negligible and power consumption is minimized. The power denial function is useful for disabling a loop which may have a ground fault. 4 SEMICMF.019 MH88612B Data Sheet R1 K1 11 VBAT ~ + D4 90 VRMS D3 15 D1 D2 48V 1 2 9 TIP RF MH88612B TF RV VR LPGND VX SHK 10 8 TIP Protection Circuit RING 3 RING PD 13 20 7 RC 16 +5V VRLY 19 C1 C2 14 K1 CAP - Q1 + RD 17 CD VBAT VCC VEE 12 5 18 R3 R2 AGND R4 RC (Pin 13) 6 C3 -48V +5V -5V Components List R1 R2 R3, R4 C1 C2, C3 D1, D2, D3, D4 Q1 K1 200Ω ± 10%, 1/4W 470kΩ ± 5%, 1/4W 10kΩ ± 5%, 1/4W 1.0µf, ± 10%, 25V electrolytic capacitor 0.1µf ± 20%, 50V ceramic de-coupling capacitors Diode rectifier 200V, 1A, IN4003 General Purpose switching transistor Relay E/M, 5V or 6V 1Form C Protection Circuit - depending on the application the Protection Circuit may need to provide over-voltage and/or over-current protection. In certain circumstances no protection will be required. Figure 3 - Application Circuit SEMICMF.019 5 MH88612B Data Sheet Absolute Maximum Ratings* Parameter 1 DC Supply Voltage LPGND = AGND 2 Storage Temperature 3 Package Power Dissipation Symbol Min Max Units VCC VEE VBAT VRLY VREF TS -0.3 -15 -80 -0.3 -60 -40 +15 +0.3 +0.3 +40 +15 100 V V V V V °C 2 W PD *Exceeding these values may cause permanent damage. Functional operation under these conditions is not implied. Recommended Operating Conditions Characteristics 1 2 3 Operating Supply Voltage Storage Temperature Sym Min Typ‡ Max Units VCC VEE VREF VBAT VRLY TS 4.75 -5.25 5.0 -5.0 0 -48 5 100 5.25 -4.75 °C V V V V V 2 To 0 70 °C -60 -40 -27 Test Conditions Adjustable Storage Temperature ‡ Typical figures are at 25°C with nominal supply voltages and are for design aid only 6 SEMICMF.019 MH88612B Data Sheet DC Electrical Characteristics† - Voltages are with respect to GNDA unless otherwise stated. Characteristics 1 Sym 2 Power Consumption 3 4 Constant Current Line Feed Adjustable Loop Current Range 5 Operating Loop Resistance 6 Ring Ground Over-Current protection 7 Off-Hook Detect Output Low Voltage (On-hook) Output High Voltage (Off-hook) Off-Hook Detect Output Low Current (On-hook) Output High Current. (Off-hook) 9 10 11 Typ‡ Max Units Test Conditions Supply Current VCC VEE VBAT 8 Min RC, PD Control Input Input Low Volt (no activation) Input High Volt (activation) RC, PD control Input Input Low Current (no activation) Input high current (activation) PD Control Input Input Low Current Input High Current ICC IEE IBAT 6.6 -3.8 150 2 PC 160 1600 500 mA mA µA mA PD = Logic High PD = Logic Low, Idle mW mW Standby V BAT = -48V Active (Off Hook) 27 30 mA mA 1200 Ω VREF = AGND, V BAT = -48V Adjustable with Ext. VREF input, VBAT = -48V VBAT = -48V @ ILOOP = 18mA, RLOOP includes telephone set 40 50 mA mA 0.4 V V IOL IOH 8 -200 mA µA VIL VIH 0.7 V V ILoop ILoop 23 18 25 RLoop ILOOP = 25mA VBAT = 48V ILOOP = 30mA VBAT = 48V Active high logic VOL VOH 2.7 Active high logic 2.0 IIL 50 µA IIH 0.5 mA IIL IIH 0.5 0.3 mA mA LSTTL compatible † DC Electrical Characteristics are over recommended operating supply voltages. ‡ Typical figures are at 25°C with nominal ±5V supplies and are for design aid only. SEMICMF.019 7 MH88612B Data Sheet AC Electrical Characteristics Characteristics Sym Min 17 1 Ringing Voltage (rms) VRING 2 3 Ringer Equivalence Number Ring Trip Detect time REN 4 5 Input AC Impedance 2-wire Input Impedance at VR Zin 6 7 Output Impedance at Vx Gain 2-wire to Vx -1.3 Gain relative to Gain @ 1kHz -0.15 Gain VR to 2-wire -1.3 Gain relative to Gain @ 1kHz -0.15 8 9 2-wire Return Loss over 300-3400Hz 10 Transhybrid Loss 11 Longitudinal to Metallic Balance over 300-3400 Hz 12 Total Harmonic Distortion at VX Typ‡ Max Units Test Conditions 90 25 Vrms Hz Superimposed on VBAT = -48V 200 ms Cap = 1uF 600 100 Ω kΩ 3 10 -1.0 -0.7 Ω dB +0.15 -1.0 -0.7 dB +0.15 dB Input 3dBm, 1kHz across Tip and Ring 300-3400 Hz Input 1.0 Vrms 1kHz at VR ZLoad = 600Ω 300 - 3400 Hz Input 0.5 Vrms , 1kHz across Tip and Ring, ZLoad = 600Ω RL 20 30 dB THL 20 30 dB Input 0.5 Vrms , 1kHz at V R ZLoad= 600Ω 50 55 dB Input 0.5 Vrms Input 3dBm, 1 kHz across Tip and Ring, THD at Tip and Ring 13 Common Mode Rejection Ratio 2-wire to Vx CMRR 14 15 Idle channel Noise Power supply rejection ratio VCC VEE VBAT Nc PSRR 40 0.1 1.0 % 0.1 1.0 % 50 14 26 26 26 Input 1.0 Vrms 1kHz at VR dB Input 0.5Vrms, 1kHz dBrnC C @ & VX Message dB dB dB 1 VPP ripple, 1kHz on VCC/VEE/VBAT,measure at VX and across Tip & Ring ‡ Typical figures are at 25°C with nominal ±5V supplies and are for design aid only. 8 SEMICMF.019 MH88612B Data Sheet 0.08 Max 0.12 Max (2.03 Max)(3.05 Max) 2.120 Max (53.85 Max) 0.6 Max (15.24 Max) 1 0.180 + 0.020 (4.57 + 0.51) 0.020 + 0.005 (0.5 + 0.13) 0.010 + 0.002 (0.25 + 0.05) *0.05 + 0.02 * 0.100 + 0.010 (1.25 + 0.51) (2.54 + 0.25) Notes: 1) Not to scale 2) Dimensions in inches. (Dimensions in millimetres) 3) Pin tolerances are non-accumulative. 4) Recommended soldering conditions: wave soldering max. temp: 260°C for 10 secs. * Dimensions to centre of pin. Figure 4 - Mechanical Data SEMICMF.019 9 For more information about all Zarlink products visit our Web Site at www.zarlink.com Information relating to products and services furnished herein by Zarlink Semiconductor Inc. or its subsidiaries (collectively “Zarlink”) is believed to be reliable. However, Zarlink assumes no liability for errors that may appear in this publication, or for liability otherwise arising from the application or use of any such information, product or service or for any infringement of patents or other intellectual property rights owned by third parties which may result from such application or use. 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