Datasheet MH88510, MH88511 Datasheet (MITEL)



MH88510/11

Subscriber Line Interface Circuit (SLIC)

Preliminary Information

Features

• High Gain v ersio n MH88 511

• Compatible with popul ar MH8 8500

• Operates wi th a wide rang e of bat tery vol tag es

• Constant current battery feed

• Dry line comp atib le

• Overvoltag e and s hort circuit pro tect ion

• Ringing Feed

• Off-hook detection and LED indicator drive

• Dial pulse detection

• Ring trip filter with auto ring trip

• Relay drive r

• Transformerless 2-2 wire conversion

• Low power co nsu mptio n

• Mute of inco ming aud io

• Few externa l com pon ents

Applications

• Line Interface for:

• PABX

• Intercoms

• Key System s

ISSUE 1 April 1995

Ordering Information

MH88510 20 Pin SIL Pa ckag e
MH88511 20 Pin SIL Pa ckag e

0°C to 70°C

Descript io n

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.

TF

TIP

RING

RF

VBAT

Tip

Drive

2-2 Wire

Hybrid

Current &

Voltage

Sensing

Ring Short
Protection

AGND

VDD VEE

Figure 1 - Functional Block Diagram

Ring Trip

Line

Super vi si on

SHK

Current/Vo lt age

Filter

RRC

LED

Constant

Control

RRD

Relay
Driver

VRLY

MUTE
JUNC

RGND

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 Description

1TIPTip Lead. Connects to the “Tip” lead (A-wire) of the telephone line .
2VDDPositive 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-wi re) of the telephon e line.
4RFRing Feed. Connect t o 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.
7AGNDAnalog Ground. Supply and batte ry ground. Internally conne cted to pin 13. For

optimum perform ance connect pin 7 to pin 13.
8V

EE

9LED

10 SHK

Negative Pow er Su pp ly Voltage. Normally -5V.

LED Drive (Output). Drives an LED directly. A logic low indicates an off-hook condition.

Switch Hook Detect (Output). A logic low indicate s an off-hook condition.

11 IC Internal Connection . This pin is connected internally
12 V

DD

Positive Power Supply Voltage. Normally +5V. This provides current for both internal

circuitry as well as the loop.

13 AGND Analog Gro und. Supply and battery ground. Internally connected to pin 13. For

optimum perform ance connect pin 13 to pin 7.

14 V

BAT

15 MUT E

Battery Voltage Supply. Normally -24V or -48V. Not internally connected to pin 6.

MUTE (Input). A logic low will mute signals coming from Tip-Ring to the JUNC.

16 JUNC Recei ve/ trans mit aud io speech path. (Referen ced to 0V GND).
17 RRD

Ring Relay Drive (Outpu t). Connects to the ring relay coil. A logic low activates the

relay.

18 RGND Relay Gro und . 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 Positi ve Supply Voltage. Normally +5V. Connects to the relay coil and the relay

supply voltage. An internal clamp diode from VR LY to RGND is provided.

2-54

Preliminary Information MH88510/11

Functional Description

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

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

supply, loop current flows through both the V

V

DD

BAT

supply and the VDD supply.

Overvoltage Protection

The MH88510/11 is protected from short ter m (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.

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.

Hybrid

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.

Line Impedance

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 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

TIP

RING

TIP

RING

1

TIP

3

RING

1

TIP

3

RING

JUNC

MH88510/11

SLIC 2

JUNC

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.

75Ω

16

CROSSPOINT

SWITCH

75Ω

16

CROSSPOINT

SWITC H

Figure 3 - SLIC Crosspoi nt S witc h Connecti on

2-55

MH88510/11 Preliminary Information

The SHK output has low drive capability while the

output can drive an LED directly. The detection

LED
circuit engages a ringing filter during applied ringing.
The ringing filter ensures that the SHK
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.

output toggles

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.

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

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.

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

Preliminary Information MH88510/11

TYPICAL

RETURN
LOSS
(dB)

10
20

30
40
50

60

550

600 650

700 750

800

850 900

LOAD IMPEDANCE ON JUNCTOR (Ω)

Figure 4 - Return Loss VS Junctor Lo ad I mped ance

950

TIP

RING

RINGING

GENERATOR

90VRMS

Notes:

R1= 200Ω, 1/4W, 5%
K1= Relay E/M 5V, 1 form C
C1, C2 = 0.1uF, 50V, Ceramic

OPTIONAL

PROTECTION

CIRCUIT

K1

R1

~

-48V

1

3

4

6,14

-5V

MH88510/11

TIP

RING

RF1

VBAT

AGND VDD RGND

VEE

813 12

C1 C2

+5V

JUNC

MUTE

SHK

LED

RRC

RRD

VRLY

18

16

15

10

19

17

20

AUDIO
INPUT/OUTPUT

MUTE CONTROL
INPUT

SWITCH HOOK
OUTPUT

9

DS1

K1

OFF-HOOK LED

RING CONTROL
INPUT

Figure 5 - Typical Applicati on Circuit

2-57

MH88510/11 Preliminary Information

Absolute Maximum Ratings

†

Parameter Symbol Min Max Units

1 DC Supply Voltage V

2 DC Battery Voltage V
3 DC Relay Voltage V

V

DD
EE

BAT

RLY

-0.3

0.3

15

-15

0.3 -60 V

-0.3 20 V
4 A C Ring Generator Voltage 150 V
5 S torage Temperature T

† Exceeding these values may cause permanen t damage . Function al operation under these condition s is not implied.

Characteristics Sym Min Typ

1 DC Supply Voltage V

2 DC Battery Voltage V
3 DC Relay Vol tage V

V

DD
EE

BAT

RLY

4.75

-4.75

-23 -48 -56 V

4 AC Ring Generator Voltage

S

‡

5.0

-5.0

5.0 15 V
90 105

Ringing Generator Frequency 17

5 Operating Temperat u re T

‡ Typical figures are at 25°C with nominal+

DC Electrical Characteristics

5V supplies and are for design aid only: not guaranteed and not subject to product ion testi ng.

†

Characteristics Sym Min Typ

OP

070°C

‡

Max Units Test Conditions

-55 125 °C

Max Units Test Conditions

7.35

-8.40

33

V

V
V

RMS

Hz

V
V

RMS

1 Supply Current: Open Loop

Normal Loop

Short Loop

2 Power Consumption①: Open Loop

Normal Loop

Short Loop

3 Low Level Output Voltage ②

High Level Output Voltage

4 Sink Current, LED

Sink Current, LED

to AGND ②
to VDD

5 Sink Current, Relay to VDD

Clamp Diode Current
6 High Level Input Voltage ③
7 Low Level Input Voltage ④

† DC Electrical Characteristics are over recommended operating conditions with V
‡ Typical figures are at 25°C with nominal+

① Supply Current and Power Consumption characteristics are over recommended operating conditions with VDD at 5.0V, VEE at -5.0V and V

loop current flows through both the V

out put consists of a 100kΩ resistor in series with an op-amp with a minimum output voltage swing of ±3.25V.

② SHK
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.

5V supplies and are for design aid only: not guaranteed and not subject to production testing.

and the VDD suppl y.

BAT

I
I

I

BAT

I
I

I

BAT

I
I

I

BAT

PC
PC
PC

V
V

I
I

I
I

V
V

DD
EE

DD
EE

DD
EE

OL

OH

OL
OH

OL
CD

15
15
15
43
15
43
43
15
43

880
2360
2360

-3.0

3.0

0.6

2.5

100

mA

R

LOOP

mA
mA
mA

R

LOOP

mA
mA
mA

R

LOOP

mA
mA

mW
mW
mW

V
V

R

LOOP

R

LOOP

R

LOOP

IOL = 2µA

= 2µA

I

OH

mAmAVOL = -1.5V

= 3.25 V

V

OL

mAmAVOL = 0.35V

150

IH

IL

3.5 V

0.8 V

at +5.0V and VEE at -5V ± 5% unless otherwise stated.

DD

IIL = 1.0mA
IIL = 0.5mA

= Open

= 1000Ω

= 0Ω

= Open
= 1000Ω
= 0Ω

at -48V. Note that

BAT

2-58

Preliminary Information MH88510/11

AC and DC Loop Electrical Characteristics*

Characteristics Sym Min Typ

1 Maximum AC Ringing

44 mA

‡

Max Units Test Conditions

Current Rejection ①
2 Ring Trip Detect Time 125 ms
3 Operating Loop Current

= -48V

V

BAT

= -23V

V

BAT

4 Maximum Operating Loop

Resistance ② V

BAT

V

BAT

= -48V

= -23V

5 Loop Current at

Off-Hook Detect Threshold

* 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 desig n aid only.
① The SLIC can be loaded with an AC impedance as low as 2200Ω without generating a false SHK

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.

I

IP

R

IP

I

SH

18
18

2000

600

8
9

23
23

10
11

28
28

12
13

mAmAR

Ω
Ω

R

I

Loop

I

Loop

Loop
Loop

< 2000Ω
< 600Ω

= 18mA
= 18mA

µAµAVDD = 5.0V, VEE = -5.0V

= 7.0V, VEE = -8.0V

V

DD

output. Since each REN represents 8kΩ,

AC Electrical Characteristics

Characteristics Sym Min Typ

1 Return Loss at 2-Wire 20 30 dB Reference 600Ω

‡

Max Units Test Conditions

@ 1kHz
2 Impedance at Junctor 604 Ω
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 Junctor

6 Total Harmonic Distortion

at Junctor

7 Idle Channel Noise

at Junctor

8 Power Supply Rejection Ratio at

at 2-Wire

at 2-Wire

at 2-Wire

THD

Nc

PSRR

3.5

3.5

1.0

1.0

12
12

dBm
dBm

%
%

dBrnc
dBrnc

% THD <

Reference: 600Ω

Reference: 754Ω

Input 0.5V 1kHz

Reference: 600Ω

Reference: 754Ω

Ripple 0.1V 1kHz

5%

2-Wire and Junctor

V

DD

V

EE

V

BAT

25
25
25

dB
dB
dB

9 Mute Attenuation 30 dB Input 0.5V MUTE

= 0.0V @1kHz

‡ Typical figures are at 25°C with nominal + 5V supplies and are for desig n aid only.

2-59

MH88510/11 Preliminary Information

AC Gains Table - MH88510

‡

Characteristics Sym Min Typ

Max Units Test Conditions

1 Gain 2-Wire to Junctor 1.05

0.42

2 Frequency Response Gain

-0.3 0.3 dB 200Hz - 3400Hz

(relative to gain at 1kHz)

3 Gain Junctor to 2-Wire 0.96

-0.35

4 Frequency Response Gain

-0.3 0.3 dB 200Ηz - 34 00Hz

(relative to gain at 1kHz)

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

AC Gains Table - MH88511

†

Characteristics Sym Min Typ

1 Gain 2-Wire to Junctor 1.15

0.21

2 Frequency Response Gain

-0.3 0.3 dB 200Hz - 3400Hz

(relative to gain at 1kHz)

3 Gain Junctor to 2-Wire 1.04

0.34

4 Frequency Response Gain

-0.3 0.3 dB 200Hz - 3400Hz

(relative to gain at 1kHz)

1.12

0.98

1.00

0.0

1.19

1.50

1.08

0.67

1.19

1.51

1.04

0.35

‡

Max Units Test Conditions

1.22

1.72

1.11

0.91

V/V

dBV

V/V

dBV

V/V

dBV

V/V

dBV

Input 0.5V 1 k Hz
Input 0.5V 1 k Hz

Input 0.5V 1 k Hz
Input 0.5V 1 k Hz

Input 0.5V 1 k Hz
Input 0.5V 1 k Hz

Input 0.5V 1 k Hz
Input 0.5V 1 k Hz

† AC Electrical Characteristics are over recommended operating conditions unless otherwise stated.
‡ Typical figures are at 25°C with nominal +

Note1: All of the above test conditions use 754Ω connected betwe en JUNC and GRD, and 600W connected betwee n Tip and Ring unless

otherwise stated.

Note 2:All of the above test conditions use 200Hz to 6400Hz unless otherwise stated.

Notes

RV1,2,3 = 175VAC, 225VAC, 15J
GE V175LA2 or similar

5V supplies and are for design aid only.

PROTECTION CIRCUIT

TIP

RV2

RV3

RV1

RING

EARTH GROUND SYSTEM

3

TIP

RING

MH88510/11

AGND

7

GROUND

1

2-60

Figure 6 - Ty pical Protection Circuit

Preliminary Information MH88510/11

MH88511

J

1

T

D1

D2

R

3

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

T1

C1

Q3

R7

LINE SEIZE

C2

C3

Q1

Q2

R3

C4

D3

D4

D6

D5

D7

R1

R2

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 (o r EQU IVALENT) 60 0Ω:1

D8

RELA Y

C5

TIL111

C6

D9

R4

R5

2

1

+5V

VAR1

TIP

R9

VAR2

+5V

R6

RING

DET

5

6

4

V AR3

R8

RING

Figure 7 - M H88511 as a Trunk Interfac e Ap plicati on

MH88510

1dB -2dB 0dB

0dB 1dB -1dB -1dB

MT8816

MH88510

Figure 8a - Line to Line

2-61

MH88510/11 Preliminary Information

C.O.

0dB -0.2dB

Side View

T1

-0.2dB

MH88511

1dB -2dB 0dB

1.2dB -0.7dB -0.7dB

MT8816

MH88510

Figure 8b - Li ne to Lin e

0.080 Ma x
(2.0 Max)

2.00 + 0.020

0.5)

(50.8 +

0.010 +
(0.25 +

Notes:

1) Not to scale

2) Dimensions in inches).

3) (Dimensions in millimetres).
*Dim ension s to cen tre of pi n &

tolerance non accumulative.

0.00 2

0.05)

0.02

0.58+
1 2 3 4 19 20

0.5)

(14.7+

0.12 Max
(3.1 Max)

0.01

0.05 +

0.5)

(1.3 +

0.05 +

(1.3 +

Figure 9 - Mechanical Data

0.02

0.18 +
(4.6 +

***

0.02

0.05)

0.020 +

(0.51 +

0.05

0.13)

0.100 +
(2.54 +

0.10

0.13)

0.5)

2-62