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MH88524
(R)
Dual 2-4 Wire Circuit Preliminary Information
Features
* * * * * * Full duplex operation Two complete circuits per package Transformerless 2-4 Wire (4-2 Wire) conversion + 5V operation Wide bandwidth (50kHz) Small Package Size MH88524
ISSUE 4
April 1995
Ordering Information 10 Pin SIL Package 0C to 70C
Description
The Mitel MH88524 (Dual 2-4 wire Circuit) provides two independent interfaces between4-Wire devices such as the MH88631 COIC (Central Office Interface CIrcuit) and a speech switch such as the MT8814 (Analog Switch Array), requiring only a single bidirectional switch per crosspoint. The MH88524 can accommodate two full duplex audio links. The device is fabricated as a thick film hybrid which incorporates various technologies for optimum circuit design and very high reliability.
Applications
4-2 Wire and 2-4 Wire conversion for: * * * * * * * * * MH88630/631, MH88632, MH88500 & MT8840 PBX Key Telephone System Channel bank Voice Mail Terminal Equipment Digital Loop Carrier Modem Intercom
RX1
Receive Gain Circuit1 2-4 Wire Circuit 1 JUN1
TX1
Transmit Gain Circuit 1
RX2
Receive Gain Circuit 2
2-4 Wire Circuit 2
JUN2
TX2
Transmit Gain Circuit 2
VDD
VEE
AGND
Figure 1 - Functional Block Diagram
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MH88524
Preliminary Information
RX1 JUN1 TX1 VDD AGND VEE IC TX2 JUN2 RX2
1 2 3 4 5 6 7 8 9 10
Figure 2 - Pin Connections
Pin Description
Pin # 1 2 3 4 5 6 7 8 9 10 Name RX1 JUN1 TX1 VDD AGND VEE IC TX2 JUN2 RX2 Description Receive 1 (Input). 4-Wire ground (AGND) referenced audio output. Junctor 1 (Transmit and Receive). Ground referenced transmit and receive speech path. Transmit 1. 4-Wire ground (AGND) referenced audio output. Positive Supply Voltage. Typically +5V. Analog Ground. 2-Wire and 4-Wire ground. Normally connected to System Ground. Negative Supply Voltage. Typically -5V. Internal Connection. This pin is internally connected. Transmit 2 (Output). 4-Wire ground AGND) referenced audio output. Junctor 2 (Transmit and Receive). Ground referenced transmit and receive speech path. Receive 2 (Input). 4-Wire ground (AGND) referenced audio output.
Absolute Maximum Ratings*
Parameter 1 2 DC Supply Voltage Storage Temperature Sym VDD VEE TS Min -0.3 +0.3 -55 Max 15 -15 125 Units V V C Comments With respect LGND
* Exceeding these values may cause permanent damage. Functional operation under these conditions is not implied.
Recommended Operating Conditions
Parameter 1 2 DC Supply Voltage Operating Temperature Sym VDD VEE TOP Typ* 5.0 -5.0 Min 4.75 -4.75 0 Max 10 -10 70 Units V V C Comments
* Typical figures are at 25C with nominal +5V supplies and are for design aid only.
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Preliminary Information
DC Electrical Characteristics
Characteristics 1 2 Supply Current Power Dissipation Sym IDD PEE PC Min Typ* Max 4 4 40 Units mA mW
MH88524
Test Conditions VDD = +5.0 VEE = 5.0 VDD = +5.0 VEE = 5.0
DC Electrical Characteristics are over recommended operating conditions unless otherwise stated. * Typical figures are at 25C with nominal +5V supplies and are for design aid only.
AC Electrical Interdependence Characteristics
Characteristics 1 Cross, Circuit 1 or 2 JUN1 to JUN2 JUN1 to TX2 RX1 to JUN2 RX1 to TX2 JUN1 to JUN2 JUN1 to TX2 RX1 to JUN2 RX1 to TX2 2 Crosstalk, Circuit 1 or 2 JUN1 to JUN2 JUN1 to TX2 RX1 to JUN2 RX1 to TX2 JUN1 to JUN2 JUN1 to TX2 RX1 to JUN2 RX1 to TX2 80 80 80 80 60 60 60 60 dB dB dB dB dB dB dB dB 80 80 80 80 60 60 60 60 dB dB dB dB dB dB dB dB Input 1.0V 200Hz-3400Hz Sym Min Typ* Max Units Test Conditions Input 1.0V 200Hz-3400Hz
200Hz-50kHz
200Hz-50kHz
AC Electrical Characteristics are over recommended operating conditions unless otherwise stated. * Typical figures are at 25C with nominal +5V supplies and are for design aid only.
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MH88524
AC Electrical Characteristics
Characteristics 1 2 3 4 5 Return Loss at junctorx (Ref. = 604) Impedance at Junctor Transhybrid Lossy (Junctor - 754) Transhybrid Loss z (Frequency = 1kHz) Transhybrid Loss (Frequency = 50kHz) Input Impedance at RX Output Impedance at TX Gain RX to Junctor Frequency Response Gain (relative to gain at 1kHz) Gain junctor to TX Frequency Response Gain relative to gain at 1kHz Signal Output Overload Level at TX at Junctor Total Harmonic Distortion RX to Junctor Junctor to TX RX to Junctor Junctor to TX Idle Channel Noise at TX at Junctor Power Supply Rejection Ratio PSRR at TX and Junctor 40 VDD VEE 40 * Typical figure are at 25C with nominal +5V supplies and are for design aid only. 15 THD 0.4 0.4 1.0 1.0 Nc 2 2 % % % % AJT
ARJ
Preliminary Information
Sym
Min 46 40
Typ*
Max
Units dB dB
Test Conditions 200-3400Hz 200-50kHz 200-3400Hz 200-50kHz Junctor = 600 Junctor = 900 Junctor = 600 Junctor = 900
604 42 36 18 21 15 18 10k 5 0.99 -0.1 -0.1 -0.1 0.99 -0.1 -0.1 -0.1 6.0 6.0 1.00 0 1.00 0.0 1.01 0.1 0.1 1.0 1.01 0.1 0.1 0.1
dB dB dB dB dB dB V/V dBV dB dB V/V dBV dB dB dBm dBm Input 0.5V 1kHz 200-3400Hz 200-50kHz Input 0.5V 1kHz 200-3400Hz 200Hz-50kHz %THD<5% Reference: 600 Reference: 754 Input 0.5V 1kHz 200-3400Hz 200-3400Hz 200-50kHz 200-50kHz Reference: 600 Reference 754 Ripple 0.1V 1kHz dB dB
6 7 8 9
10 11 12
13
14
dBrnC dBrnC
AC Electrical Characteristics are over recommended operating conditions unless otherwise stated. Both of the 2-4 Wire circuits are tested. TX, RX and Junctor actually refer to TX1, RX1 and JUN1; and TX2, RX2 and JUN2. All of the above test conditions use 754 connected between Junctor and AGND, unless otherwise stated. All the above test conditions use 200Hz to 3400Hz unless otherwise stated. Notes: x RX is connected to AGND, see Figure 3. y See Figure 5. z See Figure 4.
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Preliminary Information
Functional Description
The MH88524 is a Dual 2-4 Wire Circuit used to interface between ground reference 2-Wire circuitry and ground referenced 4-Wire circuitry. The device can accommodate two full duplex audio links.
MH88524
Figure 6, shows, illustrates a typical connection between an Interface Circuit (MH88631) and the MH88524. Note how the return loss occurs when JUNi is terminated with 754. Figure 8 illustrates a typical connection between two interface circuits (MH88631), through an MH88524 and two crosspoint switches. Optimum return loss occurs when JUNi is terminated with 754. Since the JUNi input/output impedance is 604, the MH88510 JUNC input/output impedance is 604, and the crosspoint switches resistance are 75W + 75, this configuration gives optimum return loss.
Hybrid
The 2-4 Wire hybrid circuit separates the ground reference full duplex signal at JUNi (where i=1 or 2) of the switched line into receive and transmit ground referenced signals the RXi (Receive) and TXi (Transmit). The hybrid also prevents the input signal at RXi from appearing at TXi. The degree to which the hybrid minimises the contribution to the RXi signal at the TXi output is specified as transhybrid loss. For maximising transhybrid loss, see the Transhybrid Loss section. The 4-Wire side can be interfaces to a COIC such as the MH88631 for use in analog voice switched systems; or a filter/codec, such as the Mitel MT896X, for use in digital voice switched systems. The 2-wire side can be interfaces to a crosspoint switch such as the MT8816 or a junctor SLIC such as the MH88510 for use in analog voice switched systems.
Transhybrid Loss
THL = log (VRX/VTX) Transhybrid loss is maximised when the JUNi termination impedance is 754W. In addition, good transhybrid loss is indicated in Figure 4 and AC Electrical Characteristics.
Fixed Transmit and Receive Gain
Transmit Gain (JUNi to TXi, TXi/JUNi) and receive Gain (RXi to JUNi, JUNi/RXi) are both fixed at 0dBV providing the MH88524 JUNi impedance is 754.
Return Loss at Junctor
The MH88524's Junctor impedance (Zin) is fixed at 604 nominal when RXi and TXi in a feedback loop as shown in Figure 6, the JUNi impedance will change, see Return Loss with Interface Circuit.
Application with MT8840, MH88500 and MH88524
Figure 11 illustrates an application for the MH88524's wide bandwidth. The MT8840 requires a 2-4 Wire converter which has good transhybrid loss at 32kHz. Since the MH88524 operates to 50kHz, it is ideal for this application. In addition, if a SLIC (Subscriber Line Interface Circuit) is required, the MH88500 can also be used since it also has a 604 Junctor and a wide bandwidth. Mechanical Data See Figure 12.
Return Loss with Interface Circuit
To maximise return loss at Tip-Ring of the Interface Circuit, the termination impedance at Tip-Ring of the Interface Circuit (COIC or SLIC) should match the Interface Circuit's input impedance (600, 900 or complex). However, with the inclusion of the MH88524, the interface circuit's input impedance is dependent on the JUNi termination resistance. For optimum return loss the JUNi should be terminated with 754.
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MH88524
RETURN LOSS
Preliminary Information
MH88524
JUN1 TX1
TYPICAL RETURN (dB) 0 LOSS Ref: 604 10 20 30 40 50 100 1000 10,000 Frequency (Hz) 100,000
TX1 AGND
Figure 3 - Return Loss at Junctor vs Frequency with MH88524
TRANSHYBRID LOSS
MH88524
JUN1
JUNCTOR RESISTANCE
TX1
10 20
TX1 AGND
30 40 TYPICAL 50 TRANSHYBRID LOSS (dB) 60 550 600 650 700 750 800 850 900 950
Frequency (Hz)
Figure 4 - Transhybrid Loss vs Junctor Resistance with MH88524
0
MH88524
754
JUNCTOR RESISTANCE
JUN1
TX1
10 20
TX1 AGND TYPICAL TRANSHYBRID LOSS (dB)
30 40 50 100 1000 10,000 100,000
Frequency (Hz)
Figure 5 - Transhybrid Loss vs Frequency with MH88524
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Preliminary Information
MH88524
MH88524
JUN1 TX1
JUNCTOR RESISTANCE
MH88631
RX1 TIP RETURN LOSS
TX1 AGND
TX1
RING FREQ = 1000Hz
10 20 30 40 TYPICAL RETURN 50 LOSS (dB) 60 550 600 650 700 750 800 850 900 950 JUNCTOR RESISTANCE ()
Figure 6 - Return Loss vs Junctor Resistance with MH88631 and MH88524
1
RECEIVE 1 INPUT
RX1 JUN1 TX1
2
3
TRANSMIT 1 OUTPUT
JUNCTOR1 INPUT/OUPUT
10
RECEIVE 1 INPUT
RX2
JUN2
9
JUNCTOR 2 INPUT/OUTPUT
TRANSMIT 2 OUTPUT
8 TX2
VDD AGND VEE
4
5
6
+5V
-5V
Figure 7 - MH88524 Application Circuit
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MH88524
Preliminary Information
TO CO LINE TIP 1 T
MH88631 VX
MH88524 (1/2)
RX1 JUN1
VR RING 1 R RECEIVE 1 INPUT
TX1
AGND
RX1
e.g. MT8804 MT8816 etc.
TO CO LINE TIP 2 T
MH88631 VX
MH88524 (1/2)
RX2 JUN2 VR TX2
Notes: See MH88631, MT8804 and MT8816 data sheets for device details. RING 2 R
Figure 8 - Application Circuit with MH88631, Crosspoint Switch and MH88524
TO CO LINE TIP 1 T
MH88631 VX
MH88524
RX1
(1/2)
JUN1
VR RING 1 R RECEIVE 1 INPUT
TX1
AGND
RX1
e.g MT8804 MT8816 etc.
TO CO LINE TIP 2 T
MH88510
JUNC Notes: See MH88631, MT8804 and MT8816 data sheets for device details. RING 2 R AGND
Figure 9 - Application Circuit with MH88631, MH88510, Crosspoint Switch and MH88524
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Preliminary Information
MH88524
MH88524 VIN RX1 RX1 JUN1 TX1 754
RX2
JUN2 754
VOUT JUN2
TX2 VOUT TX2 VDD AGND V EE
Notes 1) In addition to the above test circuit: Apply VIN JUN1 and measure VOUT TX2 and VOUT JUN1. Apply VIN JUN2 and measure VOUT TX1 and VOUT JUN1 Apply VIN RX2 and measure VOUT TX1 and VOUT JUN1. 2) All ground connections are star configured (i.e., single point ground).
+5V
-5V
CT (Crosstalk) calculation Examples: CT = 20xlog (VIN RX1/VOUT JUN2) CT = 20xlog (VIN RX1/VOUT TX2)
Figure 10 - Application Circuit for Crosstalk Test
Analog Signal Input MH88524 Digital Data Input (2kHz max) MT8840 TX0 TXD1 RXD0 VSS RX1 RX1 TX1 JUN1 AGND 32kHz ASK plus Analog Input/Output
Digital Data Output
High Pass Filter MH88500 TIP JUNCTOR GND RING
Analog Signal Output Low Pass Filter
To Telephone Station Set Input/Output
Notes: 1) See MT8840 data sheet for device details. 2) See MH88500 data sheet for device details. Note that this device is optional in this applications circuit. 3) High Pass Filter is typically 2nd order 15kHz 4) Low Pass Filter is typically 2nd order 4kHz
Figure 11 - Application Circuit with MT8840, MH88500 and MH88524
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MH88524
Preliminary Information
Side View
0.080 Max (2.0 Max)
1.00 + 0.03 (25.4 + 0.0.08)
0.56+0.02 (14.2+0.5)
12 34
9 10
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) 0.020 + 0.05 (0.51 + 0.13) * *
0.18+ 0.02 (4.6 + 0.5)
0.100 + 0.10 (2.54 + 0.13)
Figure 12 - Mechanical Data
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