Datasheet MH88524 Datasheet (MITEL)

MH88524



Dual 2-4 Wire Circuit

Preliminary Information

Features

• Full duple x operat ion

• Two complete circuits per package

• Transformerless 2-4 W ire (4 -2 Wire) conversi on
5V operation

•+

• Wide bandwidth (50kHz)

• Small Package Size

Applications

4-2 Wire and 2-4 Wire conversion for:

• MH88630/ 631, MH88 632, MH88 50 0 & MT8 840

• PBX

• Key Telephone Sy stem

• Channel b ank

•Voice Mail

• Terminal Equipm ent

• Digital Loop Carrier

• Modem

• Intercom

ISSUE 4 April 1995

Ordering Information

MH88524 10 Pin SIL Pa ckag e

0°C to 70°C

Descript io n

The Mitel MH88524 (Dual 2-4 wire Circuit) provides
two independent interfaces between4-Wire devices
such as the MH 8 86 3 1 CO IC (Central Offi ce In te rfa c e
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.

RX1

TX1

RX2

TX2

Receive Gain

Circuit1

Transmit Gai n

Circuit 1

Receive Gain

Circuit 2

Transmit Gain

Circuit 2

VDD VEE AGND

Figure 1 - Functiona l Block Dia gram

2-4 Wire

Circuit 1

2-4 Wire
Circuit 2

JUN1

JUN2

2-73

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 # Name Description

1RX1Receive 1 (Input). 4-Wire ground (AGND) referenced audio out put .
2 JUN1 Junctor 1 (Transmit and Receive). Ground referenced transmit and receive speech path.
3TX1Transmit 1. 4-Wire ground (AGND) referenced audio output.
4VDDPositive Supply Voltage. Typically +5V.
5AGNDAnalog Gr ou nd. 2-Wire and 4-Wire ground . Normally connecte d to System Ground.
6 VEE Negative Su pp ly Voltage. Typically -5V.
7ICInternal Connection. This pin is internally connected.
8TX2Transmit 2 (Output). 4-Wire gro und AGND) referenced audi o outp ut.
9 JUN2 Junctor 2 (Transmit and Receive). Ground referenced transmit and receive speech path.

10 RX2 Receive 2 (Input). 4-Wire ground (AGND) refere nced audio output .

Absolute Maximum Ratings*

Parameter Sym Min Max Un its Comment s

1 DC Supply Voltage V

2 Storage Temperature T

* Exceeding these values ma y cause perm anen t dama ge. Functi onal operati on und er these cond ition s is not implied.

DD

V

EE

S

-0.3

+0.315-15

-55 125 °C

V

With respect LG ND

V

Recommended Operating Conditions

Parameter Sym T yp* Min Max Units Comments

1 DC Supply Voltage V

2 Operating Temperature T

* Typical figures are at 25°C with nominal +5V supplies and are for design aid only.

DD

V

EE
OP

5.0

-5.0

4.75

-4.7510-10

V
V

070°C

2-74

Preliminary Information MH88524

DC Electrical Characteristics

‡

Characteristics Sym Min Typ* Max Uni ts Test Conditions

1 Supply Current I

DD

P

EE

4
4

mA VDD = +5.0

2 Power Dissipation PC 40 mW V

‡ DC 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.

AC Electrical Interdependence Characteristics

‡

Characteristics Sym Min Typ* Ma x Units Test Conditions

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

80
80
80
80

60
60
60
60

dB
dB
dB
dB

dB
dB
dB
dB

2 Crosstalk, Circuit 1 or 2

= 5.0

V

EE

= +5.0

DD

= 5.0

V

EE

Input 1.0V
200Hz-3400Hz

200Hz-50kHz

Input 1.0V

JUN1 to JUN2
JUN1 to TX2
RX1 to JUN2
RX1 to TX2

JUN1 to JUN2
JUN1 to TX2
RX1 to JUN2
RX1 to TX2

‡ 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.

80
80
80
80

60
60
60
60

dB
dB
dB
dB

dB
dB
dB
dB

200Hz-3400Hz

200Hz-50kHz

2-75

MH88524 Preliminary Information

AC Electrical Characteristics

‡

Characteristics Sym Min Typ* Max Units Test Conditions

1 Ret urn Loss at junctor①

(Ref. = 604Ω )

46
40

dB
dB

200-3400Hz

200-50kHz
2 Impedance at Junctor 604 Ω
3 Transhybrid Loss②

(Junctor - 754Ω)

4 Transhybrid Loss ③

(Frequency = 1kHz)

5 Transhybrid Loss

(Frequency = 50kHz)

42
36

18
21

15
18

dB
dB

dB
dB

dB
dB

200-3400Hz

200-50kHz

Junctor = 600Ω

Junctor = 900Ω

Junctor = 600Ω

Junctor = 900Ω

6 Inp ut Impedance at RX 10k Ω
7 Output Impedance at TX 5 Ω
8 Gain RX to Junctor

9 Frequen cy Response Gain

(relative to gain at 1kHz)

10 Gain junctor to TX AJT 0.99

11 Frequen cy Response Gain

relative to gain at 1kHz

12 Signal Output Overload Level

at TX

at Junctor

13 Total Harmonic Distortion

RX to Junctor

Junctor to TX

RX to Junctor

Junctor to TX

14 Idle Channel Noise

at TX

at Junctor

15 Power Supply Rejection Ratio

ARJ

THD

Nc

PSRR

0.99

-0.1

-0.1

-0.1

-0.1

-0.1

-0.1

6.0

6.0

1.00

0.0

1.01

0.1

0.1

1.0

1.0001.01

0.1

0.1

0.1

0.4

0.4

1.0

1.0

2
2

V/V

dBV

dB
dB

V/V

dBV

dB
dB

dBm
dBm

%
%
%
%

dBrnC
dBrnC

Input 0.5V 1kHz

200-3400Hz

200-50kHz

Input 0.5V 1kHz

200-3400Hz

200Hz-50kHz

%THD<5%

Reference: 6 00 Ω

Reference: 7 54 Ω

Input 0.5V 1kHz

200-3400Hz

200-3400Hz

200-50kHz

200-50kHz

Reference: 6 00 Ω

Referenc e 754Ω

Ripple 0.1V 1kHz

at TX and Junctor

V

DD

V

EE

* Typical figure are at 25°C with nominal +5V supplie s and are for desig n aid only.
‡ AC Electrical Characteristics are over recommended operating conditions unless otherwise stated.

Both of the 2-4 Wire circuits are tested. TX, RX and Junctor actual ly refer to TX1, RX1 and JUN1; and TX2, RX2 and JUN2.
All of the above test conditions use 754Ω connected between Junctor and AGND, unless otherwise stated.
All the above test conditions use 200Hz to 3400Hz unless otherwise stated.
Notes:

① RX is connected to AGND, see Figure 3.
② See Figure 5.
③ See Figure 4.

40
40

dB
dB

2-76

Preliminary Information MH88524

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.

Hybrid

The 2-4 Wire hybrid circuit separates the ground
reference full duplex s ignal 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 c an be interfaces to a COIC such as
the MH88631 for use in analog voice switched
systems; or a filter/codec, such as the Mite l MT896X,
for use in digital voice switched systems.

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 7 54 Ω.

Figure 8 illustrates a typical connection bet ween two
interface circuits (MH88631), through an MH88524
and two crosspoint switches. Optimum return loss
occurs when JUNi is terminated with 754Ω. Since the
JUNi input/output impedance is 604Ω, the MH88510
JUNC input/output impedance is 604Ω, and the
crosspoint switches resistance are 75W + 75Ω, this
configuration gives optimum return loss.

Tra nshybrid 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 Gai n

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.

Return Loss at Junc tor

The MH88524’s Junctor impedance (Zin) is fixed at
604Ω nominal when RXi and TXi in a feedback loop
as shown in Figure 6, the JUNi impedance will
change, se e Re tu r n Loss with Inte rf ac e Circuit.

Return Loss with Interfa ce 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 (600Ω, 900Ω 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 754Ω.

Transmit Gain (JUNi to TXi, TXi/JUNi) and receive
Gain (RXi to JU Ni, JUNi/R Xi) are both fixed at 0dBV
providing the MH88524 JUNi impedance is 754Ω.

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 604Ω
Junctor and a wide bandwidth.

Mechanica l Data See F igure 12 .

2-77

MH88524 Preliminary Information

RETURN
LOSS

JUNCTOR

RESISTANCE

MH88524

JUN1

AGND

MH88524

JUN1

TYPICAL

TX1

TX1

RETURN

LOSS
Ref: 604Ω

(dB)

10

20

30

40

50

0

100

1000

10,000

Frequency (Hz)

Figure 3 - Retu rn L oss a t Junc tor vs Freque ncy w ith MH 885 24

TRANSHYBRID

TX1

LOSS

10

20

100,000

754Ω

JUNCTOR

RESISTANCE

AGND

MH88524

JUN1

AGND

(dB)

30

40

50

60

550

600

650

700

Frequency (Hz)

750

800

TX1

TYPICAL

TRANSHYBRID

LOSS

Figure 4 - Transhybr id Los s vs Ju nctor Re sist ance w ith MH885 24

0

(dB)

10

20

30

40

50

100

1000

10,000

TX1

TX1

TYPICAL

TRANSHYBRID

LOSS

850

900 950

100,000

2-78

Frequency (Hz)

Figure 5 - Transh ybrid Loss vs Fre que ncy wi th MH 8852 4

Preliminary Information MH88524

TYPICAL
RETURN

LOSS

(dB)

JUNCTOR

RESISTANCE

10

20

30

40

50

60

MH88524

JUN1

AGND

TX1

TX1

MH88631

RX1

TX1

TIP

RING

RETURN LOSS

FREQ = 1000Hz

JUNCTOR

RESISTANCE

(Ω)

550

600

650

700

750

800

850

900

Figure 6 - R eturn Loss vs Jun ctor Resista nce w ith MH 8863 1 and MH88 524

1

RECEIVE 1 INPUT

TRANSMIT 1 OUTPUT

RECEIVE 1 INPUT

TRANSMIT 2 OUTPUT

RX1

3

TX1

10

RX2

8

TX2

V

DD

45

AGND

JUN1

JUN2

V

EE

6

2

9

JUNCTOR1
INPUT/OUPUT

JUNCTOR 2
INPUT/OUTPUT

950

+5V -5V

Figure 7 - MH88524 Application Circuit

2-79

MH88524 Preliminary Information

Notes:

See MH88631, MT8804
and MT8816 data
sheets for device
details.

Figure 8 - Ap plic ation C ircu it with M H88 631, Cro ssp oint Switc h an d MH885 24

TO CO LINE

TIP 1

RING 1

TO CO LINE

TIP 2

RING 2

MH88631

T

R

RECEIVE 1 INPUT

MH88631

T

R

VX

VR

VX

VR

MH88524

RX1

TX1

MH88524

RX2

TX2

RX1

JUN1

AGND

JUN2

(1/2)

e.g.
MT8804
MT8816

etc.

(1/2)

(1/2)

JUN1

AGND

Notes:

See MH 88631, MT8804
and MT8816 data
sheets for device
details.

TO CO LINE

TIP 1

RING 1

TO CO LINE

TIP 2

RING 2

MH88631

T

R

RECEIVE 1 INPUT

MH88510

T

R

VX

VR

JUNC

AGND

MH88524

RX1

TX1

RX1

Figure 9 - App lica tion Ci rcuit w ith MH 886 31, MH 885 10, Cro sspo int Sw itch an d MH 88524

e.g
MT8804
MT8816

etc.

2-80

Preliminary Information MH88524

MH88524

VIN RX1

RX1

JUN1

TX1

754Ω

VOUT

Notes

1) In addition to the a bo ve 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).

TX2

Figure 1 0 - Application Circuit for Crosstalk Test

Analog Signal Input

Digital Data Input
(2kHz max)

Digital Data Output

TXD1
RXD0

MT8840

VSS

TX0

RX1

RX2

TX2

V

DD

+5V

AGND

JUN2

V

EE

-5V

VOUT

754Ω

CT (Crosstalk) calculation

Examples:
CT = 20xlog (VIN RX1/VOUT JUN2)
CT = 20xlog (VIN RX1/VOUT TX2)

MH88524

RX1

TX1

AGND

JUN2

32kHz ASK plus

Analog Input /Output

JUN1

Analog Signal 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 Circu it with MT884 0, M H8850 0 and MH88 524

High Pass

Filter

Low Pass

Filter

MH88500

JUNCTOR

GND

TIP

RING

To Telephone Stat ion

Set Input/Output

2-81

MH88524 Preliminary Information

Side View

0.010 +
(0.25 +

Notes:

1) Not to scale

2) Dimensions in inches).

3) (Dimensi ons in millimetres).
*Dimension s to centre of pin &

tolerance non accumulative.

0.002

0.05)

0.080 Ma x
(2.0 Max)

0.12 Max
(3.1 Max)

0.02

0.56+

(14.2+

0.05 +
(1.3 +

0.5)

0.01

0.5)

12 34 910

***

0.05 +

0.02

(1.3 +

0.05)

Figure 12 - Mechanical Data

0.02 0 +
(0.51 +

1.00 + 0.03

0.0. 08)

(25.4 +

0.05

0.13)

0.100 +
(2.54 +

0.10

0.13)

0.18+
(4.6 +

0.02

0.5)

2-82