2-13

Features

FAX and Modem interface (V29)

Variants available with different line
impedances

Provides reinforced barrier to international PTT
requirements

Transformerless 2-4 Wire conversion.

Integral Loop Switch

Dial Pulse and DTMF operation

Line state detection outputs

Loop current/ringing outputs

Single +5V operation, low on-hook power
(5mW)

Full duplex data transmission

Applications

Interface to Central Office or PABX line for:

Modem

FAX

Telemetry

Description

The Mitel MH88422 Data Access Arrangement
(D.A.A.) provides a complete interface between data
transmission equipment and a telephone line. All
functions are integrated into a single thick film hybrid
module which provides high voltage isolation, very
high reliability and optimum circuit design needing a
minimum of external components.

A number of variants are available to meet particular
country impedance requirements. The D.A.A. has
been designed to meet regulatory approvals
requirements in these countries.

Figure 1 - Functional Block Diagram

Opto-

Isolation

Logic Input

Buffer

Opto-

Isolation

Opto-

Isolation

Opto-

Isolation

Audio

Buffer

Audio
Buffer

Buffer

Transhybrid

loss

cancellation

circuit

Isolation Barrier

VDD

AGND

RVLC

TIP

RING

User Connections

Network Connections

Input Buffer

TXIN

RLS

Ring & Loop

Line Termination

DS5067

ISSUE 10

November 1998

Ordering Informations

MH88422-1/2/3 26 Pin DIL Package
MH88422BD-1 26 Pin DIL Package

C to 70

MH88422

Data Access Arrangement

Preliminary Information

MH88422

Preliminary Information

2-14

Figure 2 - Pin Connections

Notes:
1. Variant 1, 4 BD-1 - pins 10,12, & 21 are cropped short. Pin 23 is not fitted.
2. Variant 2 - pin 23 is cropped short. Pins 10, 12 & 21 are not fitted.
3. Variant 3 - pins 12 and 21 are cropped short. Pins 10 and 23 are not fitted.

Pin Description

Pin #

Name

Description

VDD

Positive Supply Voltage. +5V.

2, 4, 6,

8, 9

Internal Connection. This pin is cropped short.

AGND

Analog Ground. 4-Wire Ground. Normally connected to System Ground.

Loop Control (Input). A logic 0 activates internal circuitry which provides a line
termination across Tip and Ring. Used for seizing the line and dial pulsing.

RVLC

Ringing Voltage and Current Detect (Output). Indicates the status of loop current
and ringing voltage.

10, 12

IC/NP

Internal Connection or No Pin Fitted. This pin is either cropped short or not fitted,
depending on the variant. See Note 1

Transmit (Output). Analog output to modem/fax chip set.

Receive (Input). Analog input to modem/fax chip set.

14, 17

Internal Connection. This pin is cropped short.

15, 19

No Pin Fitted.

RING

Ring Lead. Connects to the "Ring" lead of a telephone line.

TXIN

Dummy Ringer Connection. Connects to the "Ring" lead of a telephone line through a
dummy ringer capacitor.

Tip Feed. Connects externally to the RLS pin.

21, 23

IC/NP

Internal Connection or No Pin Fitted. This pin is either cropped short or not fitted,
depending on the variant. See Note 1

RLS

Ringing Loop Sense. Connects externally to the TF pin.

Internal Connection. This pin is cropped short.

TIP

Tip Lead. Connects to the "Tip" lead of a telephone line.

VDD

AGND

RVLC

IC/NP

1
2
3
4
5
6
7
8
9
10
11
12

26
25
24
23
22
21
20
19

TIP
IC
RLS
IC/NP
IC
IC/NP
TF
NP

IC
RING
NP

TXIN

Preliminary Information

MH88422

2-15

Functional Description

The device is a Data Access Arrangement (D.A.A.). It
is used to correctly terminate a 2-Wire analog loop. It
provides a signalling link and a 2-4 Wire line
interface between an analog loop and the
subscriber's data transmission equipment such as
Modems, Facsimiles (Fax's), Remote Metering and
Electronic Point of Sale equipment (EPOS).

Isolation Barrier

The device provides an isolation barrier implemented
by using optocouplers. This is a reinforced barrier for
an instantaneous power surge of up to 3kV r.m.s

., for

example a lightning strike. It also provides full
isolation for a continuous AC voltage level of up to
250V r.m.s.

External Protection Circuit

Should the input voltage from the line exceed that
isolated by the optocoupler, an External Protection
Circuit assists in preventing damage to the device
and the subscriber equipment. See Figure 3.

Line Termination

When Loop Control (LC) is at a logic 0, a line
termination is applied across Tip and Ring. The
device can be considered off-hook and DC loop
current will flow. The line termination consists of both
a DC line termination and an AC input impedance.

When LC is at a logic 1, a Dummy Ringer is applied
across Tip and Ring. The device can be considered
on-hook and negligible DC current will flow. The
dummy ringer is an AC load, which represents a
telephone's mechanical ringer.

DC Line Termination

When LC is at a logic 0, an active termination is
applied across Tip and Ring, at which time it can be
considered to be in an off-hook state. This is used to
terminate an incoming call, seize the line for an
outgoing call, or if it is applied and disconnected at
the required rate, can be used to generate dial
pulses. This termination resembles approximately
300

resistance, which is loop current dependent.

Input Impedance

The MH88422 is available in a number of different
variants each of which has its own fixed Tip-Ring AC
input impedance (Zin). Each variant is identified by
the final digit in its part number, as listed below. Also
shown are the countries whose PTT requirements
match these impedances.

MH88422-1 Zin = 220

+ 820

// 120nF

Australia / South Africa / Spain

MH88422BD-1 Zin = 220

+ 820

// 115nF

German BABT ZV5

MH88422-2 Zin = 600

North America

MH88422-3

Zin = 370

+ 620

// 310nF

UK / New Zealand

Many of these countries now pass equipment
approved to CTR21. The MH88422 will not meet this
specification. See the MH88437 datasheet for a
CTR21 Product.

Dummy Ringer

This device supports a dummy ringer option which
can be configured by the inclusion of external
components. Further details relating to component
values and configuration can be obtained from
MSAN-154. For example, Figure 3 shows capacitor
C2 which if set to 1.8

F would meet the New

Zealand dummy ringer requirements.

2-4 Wire Conversion

The device converts the balanced 2-Wire input,
presented by the line at Tip and Ring, to a ground
referenced signal at VX, as required by modem/fax
chip sets.

Conversely the device converts the ground
referenced signal input at VR, to a balanced 2-Wire
signal across Tip and Ring.

During full duplex transmission, the signal at Tip and
Ring consists of both the signal from the device to
the line and the signal from the line to the device.
The signal input at VR, being sent to the line, must
not appear at the output VX. In order to prevent this,

MH88422

Preliminary Information

2-16

the device has an internal cancellation circuit. The
measure of attenuation is Transhybrid Loss (THL).
The Transmit (VX) and Receive (VR) signals are
ground referenced (AGND), and biased to 2.5V. The
device must be in the off-hook condition for
transmission or reception to take place.

Transmit Gain

The Transmit Gain of the MH88422 is the gain from the
differential signal across Tip and Ring to the ground
referenced signal at VX. The internal Transmit Gain of
the device is fixed and depends on the variant as
shown in the AC Electrical Characteristics table. For
the correct gain, the Input Impedance of the MH88422
variant used, must match the specified line
impedance.

By adding an external potential divider to VX, it is
possible to reduce the overall gain in the application.
The output impedance of VX is approximately 10

and

the minimum resistance from VX to ground should be
2k

Example: If R1 = R2 = 2k

in Figure 3, the gain would

reduce by 6.0dB.

Receive Gain

The Receive Gain of the MH88422 is the gain from the
ground referenced signal at VR to the differential
signal across Tip and Ring. The internal Receive Gain
of the device is fixed as shown in the AC Electrical

Characteristics table. For the correct gain, the Input
Impedance of the MH88422 variant used, must match
the specified line impedance.

The input impedance to ground of VR is 47k

and this

can be used with an external series resistor to form a
potential divider and reduce the overall gain in the
application.

Example: If R3 = 100k

, in Figure 3, the Gain would

reduce by 3.0dB.

Supervisory Features

The device is capable of monitoring the line
conditions across Tip and Ring, this is shown in
Figure 3. The Ringing Voltage Loop Current detect
pin (RVLC), indicates the status of the device. The
RVLC output is at logic 0 when loop current flows,
indicating that the MH88422 is in an off hook state.

When the device is generating dial pulses, the RVLC
pin outputs a TTL pulse at the same rate.

An AC ringing voltage across Tip and Ring will cause
RVLC to output a TTL pulse at double the ringing
frequency with an envelope determined by the
ringing cadence.

Mechanical Data

See Figure 10, for details of the mechanical
specification.

Figure 3 - Typical Application Circuit

TIP

RLS

TXIN

RING

RVLC

AGND

VDD

TIP

RING

+5V

Audio

Input

Audio

Ring Voltage & Loop

Current Detect Output

Loop Control Input

MH88422

Protection

Circuit

Output

Notes:
1) R1, R2: Transmit Gain Resistors
2) R3: Receive Gain Resistor
3) C1: 10

F 6V Tantalum

4) C2: Dummy Ringer Capacitor 250V
5) C3, C4: 10

F AC coupling Capacitors

Preliminary Information

MH88422

2-17

*Exceeding these values may cause permanent damage. Functional operation under these conditions is not implied.

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

Absolute Maximum Ratings* -

All voltages are with respect to AGND unless otherwise specified.

Parameter

Symbol

Min

Max

Units

DC Supply Voltage

-0.3

Storage Temperature

-55

+125

°C

DC Loop Voltage

BAT

-110

+110

Ringing Voltage

- 2 variant
- all other variants

-2

150
120

Vrms
Vrms

Loop Current

Loop

Recommended Operating Conditions

Parameter

Sym

Min

Typ

Max

Units

Test Conditions

DC Supply Voltages

4.75

5.0

5.25

Operating Temperatures

°C

Ringing Voltage

Vrms

150 Vrms for -2 variant

Loop Electrical Characteristics

Characteristics

Sym

Min

Typ

Max

Units

Test Conditions

Ringing Voltage
-1 Variant Only No Detect
Detect

BD-1 Variant Only No Detect
Detect

All other Variants No Detect
Detect

Vrms
Vrms

Externally Adjustable -
See MSAN-154

Ringing Frequency
BD-1 Variant Only
All other Variants

23
15

28
68

Hz
Hz

Operating Loop Current
BD-1 Variant Only
All other Variants

20
15

80
80

mA
mA

Off-Hook DC Voltage
-1 Variant

-2 Variant

-3 Variant

BD-1 Variant

6.0

2.4
3.1

6.0

6.0
6.0

28.8

6.0
6.0
7.8

9.0

14.0

10.8

V
V

V
V
V

V
V

Test circuit as Fig 4
I

Loop

=19mA (See Note 1)

Loop

=60mA

Loop

=15mA

Loop

=20mA (See Note 2)

Loop

=26mA

Loop

=15mA (See Note 3)

Loop

=90mA

Loop

=20mA (See Note 4)

Loop

=50mA

MH88422

Preliminary Information

2-18

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.

Note 1: Refer to FTZ 1TR2 section 2.2
Note 2: Refer to EIA/TIA 464 section 4.1.1.4.4
Note 3: Refer to BS6305 section 4.3.1
Note 4: Refer to ZV5 Annex 1

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.

Leakage Current
(Tip or Ring to AGND)

100V

Leakage Current on-hook
(Tip to Ring)

BAT

= -50V

DC Resistance during dialling
-1 Variant
All other Variants

200
260

220
280

Loop

= 20 - 40 mA

Dial Pulse Distortion
BD-1 Variant ON
OFF
All other Variants ON
OFF

0
0
0
0

+1
+1
+2
+2

+2
+2
+4
+4

ms
ms
ms
ms

DC Electrical Characteristics

Characteristics

Sym

Min

Typ

Max

Units

Test Conditions

Supply Current

= 5.0V, On-hook

RVLC

Low Level Output Voltage
High Level Output Voltage

2.4

0.4

V
V

= 4mA

= 0.4mA

Low Level Input Voltage
High Level Input Voltage
Low Level Input Current
High Level Input Current

2.0

0.8

-60

V
V

= 0.0V

= 5.0V

Loop Electrical Characteristics

(continued)

Preliminary Information

MH88422

2-19

Electrical Characteristics are over Recommended Operating Conditions unless otherwise stated.

Typical figures are at 25

C with nominal +5V and are for design aid only.

Note 1: All of the above test conditions use a test source impedance which matches the device's impedance.
Note 2: dBm is referenced to 600

unless otherwise stated

AC Electrical Characteristics

- MH88422 All Variants

Characteristics

Sym

Min

Typ

Max

Units

Test Conditions

Input Impedance VR

47k

Output Impedance at VX

Receive Gain (VR to 2-Wire)

2.5

3.5

4.6

Test circuit as Fig 6
Input 0.5V at 1kHz

Frequency Response Gain
(relative to Gain @ 1kHz)

All Variants

-1
-1

0
0

+1
+1

dB
dB

300Hz
3400Hz

Signal Output Overload Level
at 2-Wire
at Vx

+2.0
+2.0

+3.0
+3.0

dBm
dBm

THD < 5% @ 1kHz
I

Loop

= 20 to 40mA

Total Harmonic Distortion
BD-1 Variant at 2-Wire
All other Variants at 2-Wire
All Variants at VX

THD

1.2
1.2
1.2

2.0
2.5
2.0

%
%
%

Input -3.5dBm at 1kHz

Power Supply Rejection Ratio
BD-1 Variant at 2-Wire
at VX

All other Variants at 2-Wire
at VX

PSRR

18
18

12
12

40
40

20
20

dB
dB

Ripple 0.1Vrms 1kHz
on V

Transhybrid Loss

THL

Test circuit as Fig 6
Input -3.5dBm,
300-3400Hz at V

MH88422

Preliminary Information

2-20

Electrical Characteristics are over Recommended Operating Conditions unless otherwise stated.

Typical figures are at 25C with nominal +5V and are for design aid only
Note 1: All of the above test conditions use a test source impedance which matches the device's impedance.

Electrical Characteristics are over Recommended Operating Conditions unless otherwise stated.

Typical figures are at 25C with nominal +5V supply and are for design aid only
Note 1: All of the above test conditions use a test source impedance which matches the device's impedance.

AC Electrical Characteristics

- MH88422-1

Characteristics

Sym

Min

Typ

Max

Units

Test Conditions

Return Loss at 2-Wire
(220

+ 820

//120nF)

20
20
20

22
24
26

dB
dB
dB

Test circuit as Fig 7
300-500Hz
500-2500Hz
2500-3400Hz

Longitudinal to Metallic Balance

40
55
53

65
60
60

dB
dB
dB

Test circuit as Fig 8
50-300Hz
300-1000Hz
1000-4000Hz

Idle Channel Noise

at 2-Wire

at VX

-79
-73

-72
-58

dBmp
dBmp

Transmit Gain (2-Wire to Vx)

-1.4

-0.4

0.9

Test circuit as Fig 5
Input 0.5V @ 1kHz
Off -Hook

Frequency Response Gain
(relative to Gain @ 1kHz)

-1.6
-2.1

-0.6
-0.5

0.4
0.9

dB
dB

300Hz
3400Hz

AC Electrical Characteristics

- MH88422-2

Characteristics

Sym

Min

Typ

Max

Units

Test Conditions

Return Loss at 2-Wire
(Reference 600

)

ERL

SFRL

20
14

30
19

dB
dB

Test circuit as Fig 7
500-2500Hz
200-3200Hz

Longitudinal to Metallic Balance

Metallic to Longitudinal Balance

58
53

60
40

60
55

dB
dB

Test circuit as Fig 8
200-1000Hz
1000-3000Hz
Test circuit as Fig 9
200-1000Hz
1000-4000Hz

Idle Channel Noise

at 2-Wire

at VX

13
13

20
20

dBrnC
dBrnC

Transmit Gain (2-Wire to Vx)

-1.4

-0.4

0.9

Test circuit as Fig 5
Input 0.5V @ 1kHz
Off- Hook

Frequency Response Gain
(relative to Gain @ 1kHz)

-1.6
-2.1

-1.3
-0.5

0.4
0.9

dB
dB

200Hz
3400Hz

Preliminary Information

MH88422

2-21

AC Electrical Characteristics are over Recommended Operating Conditions unless otherwise stated.

Typical figures are at 25

C with nominal +5V and are for design aid only.

Note 1: All of the above test conditions use a test source impedance which matches the device's impedance.

AC Electrical Characteristics are over Recommended Operating Conditions unless otherwise stated.

Typical figures are at 25

C with nominal +5V and are for design aid only.

Note 1: All of the above test conditions use a test source impedance which matches the device's impedance.

AC Electrical Characteristics

- MH88422-3

Characteristics

Sym

Min

Typ

Max

Units

Test Conditions

Return Loss at 2-Wire
(370

+ 620

// 310nF)

Test circuit as Fig 7
200-4000Hz

Longitudinal to Metallic Balance

Test circuit as Fig 8
300-3400Hz

Idle Channel Noise

at 2-Wire

at VX

-80
-80

-70
-68

dBmp
dBmp

Transmit Gain (2-Wire to Vx)

-1.4

-0.4

0.9

Test circuit as Fig 5
Input 0.5V @ 1kHz
Off-Hook

Frequency Gain
(relative to gain @ 1kHz)

-1.6
-2.1

-1.3
-0.5

0.4
0.9

dB
dB

300Hz
3400Hz

AC Electrical Characteristics

- MH88422BD-1

Characteristics

Sym

Min

Typ

Max

Units

Test Conditions

Return Loss at 2-Wire
(220

+ 820

// 115nF)

Test circuit as Fig 7
300-3400Hz
Ref ZV5 Sec 2.5.2 and
2.8.3

Longitudinal to Metallic Balance

30
40
46

65
60
60

dB
dB
dB

Test circuit as Fig 8
50-300Hz
300-600Hz
600-4000Hz
Ref ZV5 Sec 2.8.2

Idle Channel Noise

at 2-Wire

at VX

-84
-75

-70
-70

dBmp
dBmp

Transmit Gain (2-Wire to Vx)

-1.4

-0.4

0.9

Test circuit as Fig 5
Input 0.5V @ 1kHz
Off-Hook

Frequency Gain
(relative to gain @ 1kHz)

-1.6
-1.2

-1.3
-0.5

-0.4

dB
dB

300Hz
3400Hz

TECHNICAL DOCUMENTATION - NOT FOR RESALE

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Tel: +1 (613) 592 2122

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Europe, Middle East,

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Tel: +65 333 6193

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Fax: +1 (770) 631 8213

Fax: +65 333 6192

Tel: +44 (0) 1793 518528

Fax: +44 (0) 1793 518581

http://www.mitelsemi.com

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