MH88614 Programmable CODEC SLIC Advance Information Features ISSUE 2 • Transformerless 2-wire to 4-wire conversion • Battery Feed • Ringing & Messaging Facility • Power Down with Wake Up output • Automatic Ring Trip • Programmable Constant Current • Earth Ground Button detection • Switch Hook detection • Interface for a programmable CODEC • Ring ground over-current protection • Impedance reflection • Loop Length Indication Ordering Information MH88614 Description The SLIC provides a complete interface between an industry standard programmable CODEC or DSP and a subscriber loop. Functions provided include battery feed, zero crossing ring control, programmable current feed, power down with wake up signal, cadenced messaging facility, switch hook & dial pulse detection, loop length indication and the capability of reflecting a programmable CODEC’s impedance or supplying a standard 600 ohm impedance to the line. The device is fabricated as a thick film hybrid using various technologies for optimum circuit design high reliability. Line Interface for • PABX Intercoms • Key Telephone Systems • Control Systems VX VR 30 Pin SIL Package 0°C to 70°C Applications • 2W-4W Converter TIP Line Drivers & Battery Feed RING Loop SHK EGB April 1995 Loop Supervision Constant Current Control LA WU LCA RE MSE Switch Circuits PD VMSG VRNG VEE VDD VBAT AGND BGND Figure 1 - Functional Block Diagram 2-129 MH88614 Advance Information IC IC TIP IC RING LOOP BGND WU EGB IC VBAT IC PD AGND VDD VEE IC VR IC 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 VX IC LCA IC LA IC VRING VMSE RE MSE SHK 21 22 23 24 25 26 27 28 29 30 Figure 2 - Pin Connections Pin Description Pin # Name 1 IC Internal Connection 2 IC Internal Connection 3 TIP Connects to the “Tip” lead of the telephone line. 4 IC Internal Connection 5 RING Connects to the “Ring” lead of the telephone line 6 LOOP Loop Length Indication. The output on this pin is proportional to the loop length / resistance, and is valid for off hook conditions only. 7 BGND Battery Ground. This pin is the return pin for the battery feed to the line and also for the message voltage supply and the Ring Voltage supply. This pin should normally be connected to AGND. 8 WU Wake Up(Output). When in the power down mode this pin goes high to indicate the phone has gone off hook. When this occurs the power down signal should be removed. 9 EGB Earth Ground Button Detection (Output) This output goes low when the ring lead or tip lead is grounded. 10 IC 11 VBAT 12 IC Internal Connection 13 PD Power Down (Input) Applying a logic 0 (Active low) will Power down the hybrid. This may be used, but must be removed to allow a call to be made or to reduce power consumption. 14 AGND 15 VDD Positive Supply. (Typically +5V). 16 VEE Negative Supply. (Typically -5V). 17 IC Internal Connection 18 VR Receive (Input). The audio input signal is applied to this pin from the programmable CODEC. This signal is internally a.c. coupled 2-130 Description Internal Connection Battery Feed Supply. This pin is the supply for the line feed. (Typically -48V). Analog Ground. This pin is the return pin for the positive and negative supplies and is normally connected to BGND. MH88614 Advance Information Pin Description- (Continued) Pin # Name Description 19 IC Internal Connection 20 VX Transmit (Output). The audio output signal appears on this pin and is internally a.c. coupled. This signal is applied to the programmable CODEC. 21 IC Internal Connection 22 LCA 23 IC Internal Connection 24 LA Loop Alarm (Output) When the loop impedance exceeds the maximum limits that the SLIC can support for a specified voltage & current this output will go low. This indicates that the SLIC will no longer support the line. Note: This pin will also pulse low if Loop Disconnect Dialling is performed, and goes low when the phone is on hook. 25 IC Internal Connection 26 VRING Ring Voltage Supply. This pin is the supply for the Ringing signal to the telephone. (Typically 90VRMS on -48V battery). 27 VMSE Message Voltage Supply. This pin is the supply for the message signal to the telephone. (Typically -100V) 28 RE Ring Enable (Input). The ringing signal is applied across Tip & Ring by applying a logic 1 to this pin while the phone is “On Hook”. Ringing will be automatically stopped when the phone goes “Off Hook” regardless of the state of the RE pin. 29 MSE Message Signal Enable (Input). A cadenced signal can be applied to this pin which will switch the VMSG voltage onto Tip & Ring. The output voltage is internally conditioned to prevent bell tinkle on the telephone. This is automatically switched off when the phone goes off hook. 30 SHK Switch Hook (Output). The output of this pin goes low when the phone goes “Off Hook” and can be used externally to switch MSE off. Loop Current Adjust (input). The circuit has two constant current settings that are logic selectable Functional Description The MH88614 is an ONS SLIC for use with a programmable / intelligent CODEC or DSP. The SLIC performs all of the normal interface functions between the CODEC and the analog telephone set whilst having such additional features as Earth Ground Button Detection, message switching and Ringing switching with zero crossing. The MH88614 is available as a 30 pin SIL package to increase board densities. 2 Wire to 4 Wire Conversion The hybrid performs 2 wire to 4 wire conversion by taking the 4 wire signal from the programmable CODEC at VR and converting it to a 2 wire differential signal at Tip & Ring. The 2 wire signal applied across Tip & Ring by the phone is converted to 4 wire signal at Vx which is the output from the SLIC to the programmable CODEC. Both the VR input & Vx output are internally a.c. coupled. Loop Supervision The Loop Supervision circuit monitors the state of the phone line and provides three different output stages. When the phone goes “Off Hook” the SHK pin goes low to indicate this state. This pin reverts to a high state when the phone goes back “On Hook” (see figure 3). When the phone is off hook the circuitry can also detect two other features of the line status namely Earth Ground Button & Loop Alarm. A logic low signal on the Earth Ground Button output indicates that an earth ground path has been applied to the Tip or Ring lead of the telephone. This function can be used for recall operations on phone sets with Earth Ground Buttons. The Loop Alarm signal low to indicate that the R Loop has been exceeded and that the circuit will no longer support the line. 2-131 MH88614 Advance Information The hybrid also provides an output which is proportional to the loop length / resistance. LA must be high for ILoop to be valid. R Loop = - [(10 x VLoop)-1.5] ILoop - 82Ω Where VLoop = the voltage at Loop ILoop = the programmed line current Europe by allowing an impedance to be reflected through the SLIC from the CODEC or DSP module. The outputs at tip & ring protected from short term over voltage between tip & gnd, ring to gnd or tip to ring reducing the requirement for secondary protection circuitry. There is also long term protection on the outputs against short circuits applied across tip & ring, tip to gnd, ring to gnd and tip & ring to gnd. Switch circuits Constant Current Control Whilst working within the RLoop maximum limit set by the I Loop & VBat levels chosen the circuit allows the loop current to be set to one of the two discrete levels by the use of the loop current adjust pin. Applying a logic low to this pin sets the constant current to the lowest level. By changing the level to a logic high the constant current is set to the highest level. This feature can be used with the loop alarm signal when setting up the line to chose the loop current setting most suitable. Line Drivers & Battery Feed The Line Drivers & Battery Feed circuit provide power to the line and allow bi-directional audio transmission. The line impedance present by the line driver circuitry is a nominal 600 ohms, allowing the circuit to be used on its own in a PABX application. The nominal impedance can be modified to look like a complex impedance such as those used within There are three switches built into the functionality of this circuit, they are Ringing Enable, Message Signal Enable and Power Denial. Ringing Enable allows a logic level to be applied to a pin and the ringing voltage superimposed on a d.c. level to then be switched onto the line. The ringing signal applied to the line at zero voltage crossing and switched off at zero current. (see figure 3). The ringing signal can be terminated by either returning the Ringing Enable pin to a logic low level or it will automatically stop when the phone goes off hook regardless of the state of the input pin. The Message Signal Enable pin provides the switching control of the message voltage. A logic high on the MSE pin applies the message voltage to the line. Internal circuitry allows the input signal to MSE to be cadenced, causing the output signal to be cadenced, without causing bell tinkle. This is possible by conditioning the rising and falling edges of the output signal. Message Signal Enable also has auto trip facility. RE IRING SHK 1 0 tt 30/45mA tt Off Hook ILOOP 0mA On Hook Figure 3 - Call Supervision 2-132 MH88614 Advance Information MSE Uncadenced trdr MSE cadenced trdr trda RE trda - MSE should be removed at least 200ms before applying RE. trdr - RE should be removed at least 120ms before applying MSE. Figure 4 - Call & Message Indication When applying ringing and message signal to the phone the two signals should be applied separately to minimise total power consumption. Figure 4 indicates how the timing of this process could best be achieved for cadenced and uncadenced message signalling. Power Denial can be applied at any time to remove the line from service. The Power Denial input enables the line to be isolated from the battery under fault conditions or for maintenance purposes. A logic low will remove the battery feed whilst a logic high will provide power to the line. Absolute Maximum Ratings* Parameter Symbol Min Max Units -0.3 +0.3 0.3 +15 -15 -60 V V V Comments 1 DC Supply Voltage VDD VEE VBAT 2 Ringing Voltage VRING 130 VRMS 3 Message Voltage VMSG -180 V VDC + AC PEAK 4 Overvoltage Tip/Gnd Ring/Gnd, Tip/Ring 300 V MAX 1ms (with power on) 5 Ringing Current IRING 45 mA 6 Message Current IMSG 6 mA 7 Short Circuit current (continuous), Tip/Gnd, Ring/Gnd, Tip/Ring 60 mA 8 Storage Temp TSTG +100 °C 9 Package Power Dissipation PDISS 2.5 W -40 TAMB 70°C max * Exceeding these values may cause permanent damage. Functional operation under these conditions is not implied. 2-133 MH88614 Advance Information Recommended Operating Conditions Characteristics Sym Min Typ* Max Units Operating Supply Voltage 4.75 -4.75 -22 50 5.00 -5.00 -48 90 5.25 -5.25 -60 100 V V V VRMS 0 -100 25 -130 70 V °C Comments 1 2 Ringing Voltage VDD VEE VBat VRING 3 4 Message Voltage Operating Temperature VMSG TO 17 to 55 Hz on a DC bias of -22V to -60V VDC + AC PEAK VBat ILoop -48V 45mA * 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 - Voltages are with respect to GNDA unless otherwise stated. Characteristics 1 Supply Current 2 Power Consumption 3 Constant Current Line Feed 4 Operating Loop (Inclusive of Tele. Set) 5 6 Max Units IDD IEE IBat 10 10 10 15 15 60 mA mA mA PD =High PC 300 1800 50 400 mW mW mW Standby, VBat = -48V LCA = Low, (Off Hook) PD = Low 30 45 35 50 mA mA LCA=Low LCA=High 750 1150 Ω Ω ILoop = 45mA ILoop = 30mA VBAT = -48V 400 Ω ILoop = 30mA VBAT =-22V RLoop Unbalanced Detection EGB 8 VMSG Bias Current 9 VMSG Voltage Drop 10 LCA, MSE, RE, PD Input Low Voltage Input High Voltage EGB, SHK, LA, WU Output Low Voltage Output High Voltage Min 25 40 SHK VMSG Leakage Current 12 Typ* Off Hook Detection Threshold 7 11 Sym 10 mA 10 mA 200 µA MSE = LOW 1.5 mA MSE = HIGH♣ VMSG = -100V 4 5 V IMSG = 3mA 0.4 2.4 0.8 V V IiI = -2mA Iih = 0.4mA 0.4 V V lol = 2mA loh = -0.4mA -5 V PD = High SHK = Low (Off Hook) VBat = -48V 2 VIL VIH 2.0 VOL VOH 2.4 VLoop 0 Test Conditions Loop Output Voltage * Typical figures are at 25°C with nominal+ 5V supplies and are for design aid only: not guaranteed and not subject to production testing. ♣ Averaged level with no load applied, and a cadence of 1s “On”, 3s “Off” . 2-134 MH88614 Advance Information AC Electrical Characteristics Characteristics 1 Sym Auto Ring Trip/Message Trip Detect Time tt 2 Impedance (2W) Zin 3 Return Loss (2W) RL 4 Transhybrid Loss THL 5 Min Typ* Max Units 100 150 ms Test Conditions VBAT -48V 600 Ω No External Feedback ♣ 22 30 dB ♣ 18 20 dB ♣ Impedance at VR 100k Ω AC coupled via 0.1µF 6 Impedance at VX 10 Ω AC coupled via 0.1µF 7 Gain VR to 2W @ 1kHz dB ZTERM @ 2W = 600Ω ZSOURCE @ VR < 10Ω 8 Gain Relative to 1kHz dB 300-3400Hz 9 Gain 2W to VX @ 1kHz dB ZSOURCE @ 2W = 600Ω ZLOAD @ VR > 100k 10 Gain Relative to 1KHz +0.3 dB 300-3400Hz 11 Longitudinal to Metallic Balance at 2W LCL 56 dB 300-3400Hz 12 Harmonic Distortion @ VX and 2W THD % 0.1Vrms @ 1kHz 13 Max. Signal Level @ VX and 2W 14 Common Mode Rejection Ratio @ 2W 15 Idle Channel Noise @ 2W @ VX 16 17 Power Supply Rejection 2W and VX VRING Voltage Drop -0.3 0 0.3 +0.3 -0.3 CMRR 48 0 0.1 40 0.3 1 1.1 Vrms 50 dB 1kHz THD < 10% 0.5Vrms @ 1kHz Nc 12 15 PSRR VDD VEE V BAT 25 25 25 35 35 40 4 5 dBrnc dBrmc CMess. Filter CMess. Filter dB dB dB 0.3Vp-p @ 1kHz Vrms I RNG = 10mA RMS * Typical figures are at 25°C with nominal+ 5V supplies and are for design aid only: not guaranteed and not subject to production testing. ♣ The 2W impedance and THL are modified to the required value by external feedback applied by the programmable codec to the hybrid where required. Values quoted are for the hybrid on its own with no external feedback. Ref. 600Ω, 300Hz to 3400Hz 2-135 MH88614 Advance Information Applications Figures 5& 6 show a typical application where the MH88614 is connected to a programmable CODEC and a phone. This SLIC has been designed to be used with minimal external components in applications where programmable CODEC’s or DSP’s are used. Secondary Protection Circuit MH88614 Vx CODEC VR Tip SD4-7 Ring SDO-3 Figure 5 - Typical System Application Loop VR VOUT SHK SD0 EGB SD1 LA WU LCA RE PD SD2 SD3 SD4 SD5 SD6 SD7 MSE PROGRAMMABLE CODEC GND VDD VSS AGND BGND VRNG VMSG Ring VIN VSS Tip VX VDD MH88614 +5V -100V -5V 90VRMS (on -48V) GND Figure 6 - Interconnection Diagram 2-136 MH88614 Advance Information Side View 0.1 Max (2.54 Max) Note 4 3.00 + 0.02 (76.2 + 0.5) 0.600 Max (15.0 Max) 30 1 0.010 + 0.002 (0.25 + 0.13) 0.175 Max (4.45 Max) * 0.05 typ (1.25 typ) * * Notes: 1) Not to scale 2) Dimensions in inches). 3) (Dimensions in millimetres). *Dimensions to centre of pin & tolerance non accumulative. 0.050 + 0.02 (1.25 + 0.5) 0.020 + 0.005 (0.51 + 0.13) 0.18+ 0.02 (4.6+ 0.5) 0.100 + 0.010 (2.54 + 0.26) Figure 7- Mechanical Diagram 2-137 MH88614 Notes: 2-138 Advance Information