MH88510/11 Subscriber Line Interface Circuit (SLIC) Preliminary Information ISSUE 1 Features April 1995 Ordering Information • High Gain version MH88511 • Compatible with popular MH88500 • Operates with a wide range of battery voltages • Constant current battery feed • Dry line compatible • Overvoltage and short circuit protection • Ringing Feed • Off-hook detection and LED indicator drive • Dial pulse detection • Ring trip filter with auto ring trip • Relay driver • Transformerless 2-2 wire conversion • Low power consumption • Mute of incoming audio • Few external components MH88510 MH88511 20 Pin SIL Package 20 Pin SIL Package 0°C to 70°C Description The Mitel MH88510/11 Subscriber Line Interface Circuit provides a complete interface between the telephone line and a speech switch requiring only single bidirectional switch per crosspoint. The functions provided by the MH88510/11 include bidirectional differential to single ended conversion in the speech path, line battery feed, ringing feed and loop and dial pulse detection. The device is fabricated as a thick film hybrid which incorporates various technologies for optimum circuit board and very high reliability. Applications • Line Interface for: • PABX • Intercoms • Key Systems TF TIP Constant Current/Voltage Control Tip Drive MUTE 2-2 Wire Hybrid JUNC Current & Voltage Sensing RING RF Ring Short Protection VBAT AGND VDD VEE Ring Trip Filter Relay Driver Line Supervision SHK LED RRC RRD VRLY RGND Figure 1 - Functional Block Diagram 2-53 MH88510/11 Preliminary Information TIP VDD RING RF TF VBAT AGND VEE LED SHK IC VDD AGND VBAT MUTE JUNCTOR RRD 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 TIP Tip Lead. Connects to the “Tip” lead (A-wire) of the telephone line. 2 VDD Positive Power Supply Voltage. Normally +5V. This provides current for both internal circuitry as well as the loop. Not internally connected to pin 12. 3 RING Ring Lead. Connects to the “Ring” lead (B-wire) of the telephone line. 4 RF Ring Feed. Connect to the Ring Relay contact. See Figure 5. 5 TF Leave open circuit 6 VBAT Battery Voltage Supply. Normally -24V or -48V. Not internally connected to pin 14. 7 AGND Analog Ground. Supply and battery ground. Internally connected to pin 13. For optimum performance connect pin 7 to pin 13. 8 VEE Negative Power Supply Voltage. Normally -5V. 9 LED LED Drive (Output). Drives an LED directly. A logic low indicates an off-hook condition. 10 SHK Switch Hook Detect (Output). A logic low indicates an off-hook condition. 11 IC 12 VDD 13 AGND 14 VBAT 15 MUTE MUTE (Input). A logic low will mute signals coming from Tip-Ring to the JUNC. 16 JUNC Receive/transmit audio speech path. (Referenced to 0V GND). 17 RRD Ring Relay Drive (Output). Connects to the ring relay coil. A logic low activates the relay. 18 RGND Relay Ground. Return path for relay supply votlage. Normally connected to AGND. 19 RRC Ring Relay Control (Input). A logic high activates the Ring Relay Drive (RRD) outputs. 20 VRLY Relay Positive Supply Voltage. Normally +5V. Connects to the relay coil and the relay supply voltage. An internal clamp diode from VRLY to RGND is provided. 2-54 Description Internal Connection. This pin is connected internally Positive Power Supply Voltage. Normally +5V. This provides current for both internal circuitry as well as the loop. Analog Ground. Supply and battery ground. Internally connected to pin 13. For optimum performance connect pin 13 to pin 7. Battery Voltage Supply. Normally -24V or -48V. Not internally connected to pin 6. MH88510/11 Preliminary Information Functional Description switches ringing voltage on to the line via the external ring relay. The SLIC provides two internal 300W battery feed resistors through which the ringing current will flow. A clamp diode is included which suppresses voltage transients during relay switching caused by the relay coil. In addition, the circuit prevents connection of the ringing source during off-hook conditions. See figure 5 for typical application. The BORSH Functions The MH88510/11 performs all of the Borsh functions of Battery Feed, Overvoltage Protection, Ringing, Supervision and Hybrid (2-2 Wire). Battery Feed Hybrid The MH88510/11 powers the telephone set with constant DC loop current for shortlines and automatically reverts to constant voltage for long lines. Since the Tip drive is powered down from the VDD supply, loop current flows through both the VBAT supply and the VDD supply. The 2-2 Wire hybrid circuit converts the incoming balanced signal at Tip and Ring of the telephone line into a ground referenced output signal at JUNC of the SLIC, and converts the ground referenced input signal at JUNC of the SLIC into a non-balanced output signal at Tip and Ring of the telephone line. Overvoltage Protection Line Impedance The MH88510/11 is protected from short term (20ms) transients (+250V) between Tip and Ring, Tip and ground, and Ring and Ground. However additional protection circuitry may be needed depending on the requirements which must be met. Normally, simple external shunt protection as shown in Figures 5 and 6 is all that is required. The MH88510/11’s Tip-Ring(Zin) impedance is fixed at 600Ω. For correct SLIC impedance, JUNC must be appropriately terminated. See AC Electrical Characteristics. Supervision Ringing The loop detection circuit determines whether a low enough impedance is across Tip and Ring to be recognised as an Off-Hook condition. When an offhook condition occurs, the SHK and LED outputs toggle to a logic low level. These outputs also toggle during incoming dial pulses. The ringing insertion circuitry has the capability to provide ringing voltage to the telephone set by simply adding an external relay, ring generator and a 200Ω limiting resistor. The internal relay driver MH88510/11 SLIC 1 75Ω 1 TIP 16 TIP JUNC RING 3 CROSSPOINT SWITCH RING MH88510/11 SLIC 2 1 TIP 75Ω TIP 16 JUNC RING 3 RING CROSSPOINT SWITCH Figure 3 - SLIC Crosspoint Switch Connection 2-55 MH88510/11 The SHK output has low drive capability while the LED output can drive an LED directly. The detection circuit engages a ringing filter during applied ringing. The ringing filter ensures that the SHK output toggles at the ringing cadence and not at the ringing frequency. The ring trip detection circuit also prevents false off-hook detection due to the current associated with the AC ringing voltage as well as current transients when the ringing votlage is switched in and out. Preliminary Information In addition, the Tip-Ring Drive Circuit has the capability to drive a dry line (a line with no DC current flowing); the AC Electrical Characteristics apply (except for longitudinal balance), even when the loop current drops to zero. Therefore, the MH88510 has the capability to drive a line much longer than 2000Ω providing the user is not concerned with loop current, SHK detection or ringing generator current. Short Circuit Protection Hybrid The 2- wire hybrid circuit converts the incoming balanced signal at Tip and Ring of the telephone line into a ground referenced output signal at JUNC of the SLIC, and converts the ground referenced input signal at JUNC of the SLIC into a non-balanced output signal at Tip and Ring of the telephone line. Return Loss at Tip-Ring To maximise return loss, the impedance at Tip-Ring should match the SLIC’s impedance (600Ω). However, the SLIC’s input impedance is dependent on the JUNC termination resistance. For a 600Ω SLIC input impedance, the JUNC must be terminated with 754Ω. Figure 2 illustrates a typical connection between two SLICs through two crosspoint switches. Optimum return loss occurs when JUNC is terminated with 754Ω. Since the JUNC input/output is 604Ω and the crosspoint switches resistance are 75Ω + 75Ω, this configuration gives optimum return loss as shown in Figure 3. MUTE A logic low at the MUTE input results on, muted signals coming from Tip and Ring to the JUNC terminal while allowing signals from the JUNC terminal to Tip and Ring to be transmitted. Tip-Ring Drive Circuit The audio input ground referenced signal at JUNC is converted to a differential output signal at Tip and Ring. The output signal consists of the audio signal superimposed on the DC battery feed current. The Tip-Ring drive circuit is optimsed for good 2-Wire longitudinal balance. 2-56 The MH88510 is protected from long term (infinite) short circuit conditions occurring between Tip and Ring, Tip and AGND, and Ring and AGND. Line Impedance The MH88510’s Tip-Ring (Zin) impedance is fixed at 600Ω. For correct SLIC impedance, JUNC must be appropriately terminated. See AC Electrical Characteristics. Transmit and Receive Gain Transmit Gain (JUNC to Tip-Ring) and Receive Gain (Tip-Ring to JUNC) are fixed. For correct gain, the SLIC input impedance must match the line impedance and JUNC must be appropriately terminated. MH88510/11 Preliminary Information TYPICAL RETURN LOSS (dB) 10 20 30 40 50 60 550 600 650 800 700 750 850 900 950 LOAD IMPEDANCE ON JUNCTOR (Ω) Figure 4 - Return Loss VS Junctor Load Impedance MH88510/11 1 TIP OPTIONAL PROTECTION CIRCUIT RING TIP 3 16 AUDIO INPUT/OUTPUT 15 MUTE CONTROL INPUT 10 SWITCH HOOK OUTPUT JUNC RING MUTE 4 SHK RF1 K1 LED R1 RRC RINGING GENERATOR 90VRMS ~ 6,14 9 19 OFF-HOOK LED DS1 RING CONTROL INPUT 17 RRD VBAT K1 VRLY 20 VEE AGND VDD RGND -48V 8 13 12 18 Notes: R1= 200Ω, 1/4W, 5% K1= Relay E/M 5V, 1 form C C1, C2 = 0.1uF, 50V, Ceramic +5V -5V C1 C2 Figure 5 - Typical Application Circuit 2-57 MH88510/11 Preliminary Information Absolute Maximum Ratings† Parameter Symbol Min Max Units 1 DC Supply Voltage VDD VEE -0.3 0.3 15 -15 V V 2 DC Battery Voltage VBAT 0.3 -60 V 3 DC Relay Voltage VRLY -0.3 20 V 4 AC Ring Generator Voltage 150 VRMS 5 Storage Temperature 125 °C TS -55 † Exceeding these values may cause permanent damage. Functional operation under these conditions is not implied. Characteristics Sym Min Typ‡ Max Units 1 DC Supply Voltage VDD VEE 4.75 -4.75 5.0 -5.0 7.35 -8.40 V V 2 DC Battery Voltage VBAT -23 -48 -56 V 3 DC Relay Voltage VRLY 5.0 15 V 4 AC Ring Generator Voltage Ringing Generator Frequency 90 17 105 33 V RMS Hz 0 70 °C 5 Operating Temperature TOP Test Conditions ‡ Typical figures are at 25°C with nominal+ 5V supplies and are for design aid only: not guaranteed and not subject to production testing. DC Electrical Characteristics† Characteristics 1 Supply Current: Open Loop Normal Loop Short Loop Sym Min Typ‡ Max Units Test Conditions IDD IEE IBAT IDD IEE IBAT IDD IEE IBAT 15 15 15 43 15 43 43 15 43 mA mA mA mA mA mA mA mA mA RLOOP = Open 880 2360 2360 mW mW mW RLOOP = Open RLOOP = 1000Ω RLOOP = 0Ω RLOOP = 1000Ω RLOOP = 0Ω 2 Power Consumption①: Open Loop Normal Loop Short Loop PC PC PC 3 Low Level Output Voltage ② High Level Output Voltage VOL VOH -3.0 3.0 V V 4 Sink Current, LED to AGND ② Sink Current, LED to VDD IOL IOH 0.6 2.5 mA mA VOL = -1.5V VOL = 3.25V 5 Sink Current, Relay to VDD Clamp Diode Current IOL ICD 100 150 mA mA VOL = 0.35V 6 High Level Input Voltage ③ VIH 3.5 V IIL = 1.0mA 7 Low Level Input Voltage ④ VIL V IIL = 0.5mA 0.8 IOL = 2µA IOH = 2µA † DC Electrical Characteristics are over recommended operating conditions with VDD at +5.0V and VEE at -5V ± 5% unless otherwise stated. ‡ Typical figures are at 25°C with nominal+ 5V supplies and are for design aid only: not guaranteed and not subject to production testing. ① Supply Current and Power Consumption characteristics are over recommended operating conditions with VDD at 5.0V, VEE at -5.0V and VBAT at -48V. Note that loop current flows through both the VBAT and the VDD supply. ② SHK output consists of a 100kΩ resistor in series with an op-amp with a minimum output voltage swing of ±3.25V. ③ LED outputs consists of a 2.5kΩ resistor in series with SHK op-amp output. RRC input consists of a 5kW resistor in series with the base lead of the relay driver transistor (grounded emitter). ④ The MUTE input is internally pulled up. With no input connection, the voltage level at the MUTE input is typically at 1.5V. 2-58 MH88510/11 Preliminary Information AC and DC Loop Electrical Characteristics* Characteristics Sym 1 Maximum AC Ringing Current Rejection ① 2 Ring Trip Detect Time 3 Operating Loop Current VBAT = -48V VBAT = -23V 4 5 Min Typ‡ Max 44 IIP Maximum Operating Loop Resistance ② VBAT = -48V VBAT = -23V R IP Loop Current at Off-Hook Detect Threshold ISH Units Test Conditions mA 18 18 125 ms 28 28 mA mA 23 23 Ω Ω ILoop = 18mA ILoop = 18mA µA µA VDD = 5.0V, VEE = -5.0V VDD = 7.0V, VEE = -8.0V 2000 600 8 9 10 11 12 13 RLoop < 2000Ω RLoop < 600Ω * AC and DC Loop Electrical Characteristics are over recommended operating conditions unless otherwise stated. ‡ Typical figures are at 25°C with nominal + 5V supplies and are for design aid only. ① The SLIC can be loaded with an AC impedance as low as 2200Ω without generating a false SHK output. Since each REN represents 8kΩ, the SLIC can drive a REN of 3.6 without generating a false SHK output. ② See section on Tip-Ring Drive Circuit for driving longer lines. AC Electrical Characteristics Characteristics Sym Min Typ‡ 20 30 dB 604 Ω Max Units Test Conditions 1 Return Loss at 2-Wire 2 Impedance at Junctor 3 Longitudinal to Metallic Balance 50 60 dB 40Hz - 4kHz 4 Longitudinal to Junctor Balance 50 60 dB 40Hz - 4kHz 5 Signal Output Overload Level at 2-Wire at Junctor 6 Total Harmonic Distortion 3.5 3.5 dBm dBm THD Idle Channel Noise Mute Attenuation % % 12 12 dBrnc dBrnc PSRR Power Supply Rejection Ratio at 2-Wire and Junctor Reference: 600Ω Reference: 754Ω Ripple 0.1V 1kHz 25 25 25 VDD VEE VBAT 9 1.0 1.0 Nc at 2-Wire at Junctor 8 % THD < 5% Reference: 600Ω Reference: 754Ω Input 0.5V 1kHz at 2-Wire at Junctor 7 Reference 600Ω @ 1kHz 30 dB dB dB dB Input 0.5V MUTE = 0.0V @1kHz ‡ Typical figures are at 25°C with nominal + 5V supplies and are for design aid only. 2-59 MH88510/11 Preliminary Information AC Gains Table - MH88510 Characteristics Sym Min Typ‡ Max Units 1.12 0.98 1.19 1.51 V/V dBV Input 0.5V 1kHz Input 0.5V 1kHz 0.3 dB 200Hz - 3400Hz 1.04 0.35 V/V dBV Input 0.5V 1kHz Input 0.5V 1kHz 0.3 dB 200Ηz - 3400Hz 1 Gain 2-Wire to Junctor 1.05 0.42 2 Frequency Response Gain (relative to gain at 1kHz) -0.3 3 Gain Junctor to 2-Wire 0.96 -0.35 4 Frequency Response Gain (relative to gain at 1kHz) -0.3 1.00 0.0 Test Conditions ‡ Typical figures are at 25°C with nominal + 5V supplies and are for design aid only. AC Gains Table - MH88511† Characteristics Sym Min Typ‡ Max Units 1.19 1.50 1.22 1.72 V/V dBV Input 0.5V 1kHz Input 0.5V 1kHz 0.3 dB 200Hz - 3400Hz 1.11 0.91 V/V dBV Input 0.5V 1kHz Input 0.5V 1kHz 0.3 dB 200Hz - 3400Hz 1 Gain 2-Wire to Junctor 1.15 0.21 2 Frequency Response Gain (relative to gain at 1kHz) -0.3 3 Gain Junctor to 2-Wire 1.04 0.34 4 Frequency Response Gain (relative to gain at 1kHz) -0.3 1.08 0.67 Test Conditions † AC Electrical Characteristics are over recommended operating conditions unless otherwise stated. ‡ Typical figures are at 25°C with nominal + 5V supplies and are for design aid only. Note1: All of the above test conditions use 754Ω connected between JUNC and GRD, and 600W connected between Tip and Ring unless otherwise stated. Note 2: All of the above test conditions use 200Hz to 6400Hz unless otherwise stated. PROTECTION CIRCUIT 1 MH88510/11 TIP TIP RV2 3 RV3 RING RV1 RING AGND 7 Notes RV1,2,3 = 175VAC, 225VAC, 15J GE V175LA2 or similar EARTH GROUND Figure 6 - Typical Protection Circuit 2-60 SYSTEM GROUND MH88510/11 Preliminary Information R7 Q3 +5V D8 LINE SEIZE C2 VAR1 RELAY TIP R3 R1 R9 C4 C3 D3 MH88511 C5 R4 D6 Q1 J T T1 1 D4 D1 D5 C6 VAR2 D9 Q2 +5V D2 R5 R6 R 3 C1 R2 RING DET 1 D7 5 TIL111 COMPONENTS D1,D2,=IN4732 D3,D4,D5,D6,D7=IN4003 D8=IN4148 D9=IN5246B VAR1,VAR2,VAR3-V130LA20A C1,C3=10µF,60V,5% C2=1.0µF,100V,5% C4=0.1µF,100V,5% C5=0.01µF,100V,5% C6=0.33µF,200V,5% R1=1/4W,1%,6.8k R2,R5=1/4W,10%,10k 2 R3=1/2W,10%,50Ω R4=1/4W,10%,680Ω R6=1/4W,10%,100kΩ R7=1/4W,10%,1kΩ R8,R9=1/2W,10%,10Ω Q1=MPSA90 Q2=ZN6716 Q3=BC238 T1=FILTRAN TPF712 (or EQUIVALENT) 600Ω:1 6 4 R8 RING VAR3 Figure 7 - MH88511 as a Trunk Interface Application MT8816 MH88510 1dB 0dB MH88510 -2dB 1dB 0dB -1dB -1dB Figure 8a - Line to Line 2-61 MH88510/11 T1 Preliminary Information MH88511 MT8816 MH88510 -2dB 0dB C.O. -0.2dB 1dB 0dB -0.2dB 1.2dB -0.7dB -0.7dB Figure 8b- Line to Line 0.080 Max (2.0 Max) Side View 2.00 + 0.020 (50.8 + 0.5) 0.58+0.02 (14.7+0.5) 1 2 3 4 19 20 0.010 + 0.002 (0.25 + 0.05) 0.12 Max (3.1 Max) Notes: 1) Not to scale 2) Dimensions in inches). 3) (Dimensions in millimetres). *Dimensions to centre of pin & tolerance non accumulative. 0.05 + 0.01 (1.3 + 0.5) * 0.05 + 0.02 (1.3 + 0.05) Figure 9 - Mechanical Data 2-62 * 0.020 + 0.05 (0.51 + 0.13) * 0.100 + 0.10 (2.54 + 0.13) 0.18 + 0.02 (4.6 + 0.5)