®
MH88615
ONS Subscriber Line Interface Circuit
Advance Information
Features
•
•
ONS SLIC
Variants
- 1 Germany
- 3 UK
- 7 North America
•
•
•
•
•
•
•
•
Transformerless 2W to 4W conversion
Battery Feed to line
Off-Hook and dial pulse detection
Tip and Ring ground over-current protection
Power Denial
Integral Ringing Amplifier
Programmable Loop Current
Wide V
BAT
Operating Range
ISSUE 1
April 1995
Ordering Information
MH88615-1
MH88615-3
MH88615-7
20 Pin SIL Package
20 Pin SIL Package
20 Pin SIL Package
0°C to 70°C
Description
The Mitel MH88615 ONS SLIC provides a complete
interface between a switching system and a
subscriber loop. The functions provided by the
MH88615 include battery feed and integral ringing
amplifier feed to the subscriber line, 2W to 4W
conversion current feed, off-hook and dial pulse
detection. The device is fabricated as a thick film
hybrid in a 20 pin single-in-line package.
Applications
Line Interface for
• PABX
•
•
•
•
•
Pair Gain Systems
Satellite Communication Systems
Key Telephone Systems
Marine Systems
Cordless Local Loop
PD
VBat
DCRI
RV
Power Denial
Ringing Control
RC
TIP
RING
Tip &
Ring
Drivers
2-Wire to 4-Wire
Conversion
VR
VX
VRef
Constant
Current Feed
Loop
Supervision
CAP
SHK
Figure 1 - Block Diagram
2-139
MH88615
TIP
RING
NC
DCRI
LPGND
VBat
NC
VDD
AGND
VEE
RC
PD
NC
SHK
VR
VRef
CAP
VX
NC
RV
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
Advance Information
Figure 2 - Pin Description
Pin Description
Pin #
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
Name
TIP
RING
NC
DCRI
LPGND
VBat
NC
VDD
AGND
VEE
RC
PD
NC
SHK
VR
VRef
CAP
Description
Tip Lead.
Connects to the “Tip” lead of subscriber line.
Ring Lead.
Connects to the “Ring” lead of subsriber line.
No Connection.
This pin may be used for internal connections.
DC Ringing Voltage Input.
A continuous 120 Vdc is applied to this pin. This voltage is the
positive supply rail for the internal ringing amplifier for subscriber line.
Battery Ground.
V
Bat
return path for subscriber line. Connects to the systems’s energy
dumping ground.
Battery Voltage.
Battery supply feed for subscriber line. Typically -48Vdc is applied to this
pin.
No Connection.
This pin may be used for internal connections.
Positive Supply Voltage.
+5V dc supply rail.
Analogue Ground.
V
DD
and V
EE
return path.
Negative Supply Voltage.
-5V dc supply rail.
Ringing Control.
This input enables the ringing voltage feed to Tip and Ring for subscriber
line.
Power Denial.
A logic high will isolate the battery voltage for Tip and Ring.
No Connection.
This pin may be used for internal connections.
Switch Hook Detect.
A logic high indicates when subscriber line has gone off-hook.
Receive Signal.
This is the 4 wire analogue signal received at subscriber’s set.
Reference Voltage.
A dc reference voltage is applied to this pin to set the constant current
feed to subscriber line. This pin may also be grounded for normal 25mA loop current.
Ring Trip Filter Capacitor.
A capacitor is normally connected from this pin to ground and
filters out low frequency ringing signals, preventing false off-hook conditions.
Transmit Signal.
This is the 4 wire analogue signal transmitted from subscriber’s set.
No Connection.
This pin may be used for internal connections.
Ringing Voltage.
1.5 Vrms signal is injected to this pin.
18
19
20
VX
NC
RV
2-140
Advance Information
Functional Description
The Mitel MH88615 ONS SLIC provides a complete
interface between a switching system and a
subscriber loop. The functions provided by the
MH88615 include battery feed and integral ringing
amplifier feed to the subscriber line, 2W to 4W
conversion, constant current feed, off-hook and dial
pulse detection. The device is fabricated as a thick
film hybrid in a 20 pin single-in-line package.
The MH88615 is intended for applications where low
cost and basic functionality is important. The
MH88615 features an integral ringing amplifier which
enables a system designer to provide typically 60
Vrms ringing without having to generate a high
voltage, high current ac signal.
The SLIC uses a transformerless 2-4 wire converter
which can be connected to a CODEC to interface the
2 wire subscriber loop to a TDM (time division
multiplex) PCM (pulse code modulation) digital link.
Powering of the subscriber line is provided though
precision battery feed resistors on the hybrid. The
thick film hybrid circuit also contains control,
signalling and status circuits which combine to
provide a complete functional solution. A power
denial facility is provided which isolates the Battery
Feed from Tip and Ring.
The MH88615 is designed to meet German
regulatory approvals, UK regulatory approvals
(BS6305), and capable of meeting the approvals for
the USA (FCC Part 68/EIA 464).
MH88615
Power Denial
A logic high voltage applied to the power denial input
effectively removes the battery voltage from the loop
driver circuitry. The resulting loop current is
negligible and power consumption is minimised. The
power denial function is useful for disabling a loop
which may have a ground fault.
The SLIC is capable of detecting and indicating off-
hook and unbalanced conditions as well as inhibiting
ringing while in power denial.
Input and Network Impedance
The Input and Network Balance Impedances are
defined by the variant type on the MH88615.
MH88615-1Germany
Z
in
= 220Ω + (820Ω//115nF)
Z
net
= 220Ω +(820Ω//115nF)
MH88615-3 UK
Z
in
= 370Ω + (620Ω//310nF)
Z
net
= 300Ω + (1000Ω//220nF)
MH88615-7 North America
Z
in
= 600Ω
Z
net
= 350Ω (1kΩ//210nF)
Ringing Amplifier
The MH88615 incorporates an integral ringing
amplifier. A nominal 1.5Vrms ac signal is applied to
the RV pin and this produces a ringing signal of
typically 60 Vrms. This should ensure that the SLIC
can support a REN of 5.
Constant Current Feed
The loop current is programmed by the dc reference
voltage applied to V
Ref
.
Switch Hook Detection
When the dc current exceeds an internal threshold
level, the switch hook output (SHK) will go high. If
the loop resistance is so high that V
Bat
can no longer
supply the required loop current, the output SHK will
go low. This indicates that the loop resistance is too
high and the line is on hook.
Transmit Gain
Transmit gain (Tip-Ring to Vx) is fixed at 0.dB. A
dcbias on the ac input signal does not effect the
ringing signal.
Receive Gain
Receive Gain (VR to TIP-RING) is fixed at 0dB.
For correct gain, the SLIC input impedance must
match the line impedance
DC Loop Current Limit
Under Tip or Ring ground conditions the loop current
is nominally limited to 42mA.
2-141
MH88615
Absolute Maximum Ratings*-
Voltages are with respect to AGND.
Parameter
1
Supply Voltages
Symbol
V
Bat
V
DD
V
EE
V
DCRI
T
S
Min
0.3
-0.3
0.3
-0.3
-55
Max
65
6
-6
140
125
Units
V
V
V
V
°C
Advance Information
Comments
With respect LPGND
With respect LPGND
2
Storage Temperature
* Exceeding these values may cause permanent damage. Functional operation under these conditions is not implied.
Recommended Operating Conditions
Characteristics
1
Supply Voltages
Sym
V
Bat
V
DD
V
EE
V
DCRI
T
OP
V
R
F
R
Min
-20
4.75
-4.75
0
0
Typ*
-48
5.0
-5.0
48
20
60
17
Max
-60
5.25
-5.25
130
70
90
68
Units
V
V
V
V
°C
V
BAT
= -48V
V
RMS
Hz
Comments
2
3
Operating Temperature
AC Ring Generator
Voltage
Frequency
* Typical figures are at 25°C with nominal +5V supplied and are for design aid only.
DC Electrical Characteristics*
Characteristics
1
Sym
I
DD
Min
Typ
Max
10
5
2.5
150
1700
Units
mA
mA
mA
mW
mW
mA
Test Comments
Supply Current
I
EE
I
Bat
2
3
4
5
PD on
Standyby
Active
V
Ref
= AGND
Power Consumption
Constant Current Line Feed
Adjustable Loop Current Range
Maximum Operating Loop
Resistance
PC
I
Loop
I
Loop
R
Loop
23
18
1200
25
27
30
mA
Ω
V
Bat
=-48V @
I
Loop
=18mA,
R
Loop
=includes
telephone set
Active High Logic
6
7
Ring Ground Over-Current
Off-Hook Detect
Output Low Voltage
Output High Voltage
Off-Hook Detect
Output Low Current
Output High Current
RC, PD Control Input
Input Low Voltage
Input High Voltage
RC, PD Control Input
Input Low Current
Input High Voltage
V
OL
V
OH
42
0.4
2.7
4
-400
0.7
2.0
-500
500
mA
V
V
mA
µA
Active High Logic
V
V
µA
µA
8
I
OL
I
OH
V
OL
V
OH
I
IL
I
IH
9
10
* -48V and are for design aid only
2-142
Advance Information
AC Electrical Characteristics*
Characteristics
1
MH88615
Sym
V
R
F
R
Min
17
100
47
-0.25
-0.15
100
10
0
0
0.25
0.15
Typ
‡
38
68
Max
Units
Vrms
Hz
ms
kΩ
Test Comments
Superimposed on
V
Bat
= -48V. RV=1.5
Vrms
Ringing voltage
2
3
4
5
6
Ring Trip Detect Time
Input Impedance at VR
Output Impedance at Vx
Gain 2-wire to Vx
Frequency Response 2-wire to Vx
Ω
dB
dB
Relative to 1kHz
300Hz to 3.4 kHz
7
8
9
10
11
12
Gain Vr to 2-wire
Frequency Response Vr to 2-wire
Total Harmonic Distortion
Common Mode Rejection Ratio
Idle Channel Noise
Power Supply Rejection Ratio at 2-
Wire or VX
THD
CMRR
Nc
PSRR
-0.25
-0.15
0
0
0.25
0.15
0.5
dB
dB
%
dB
dBrnC
dB
Ripple 0.1V
1kHz @
VDD
Relative to 1kHz
300 Hz to 3.4 kHz
50
12
25
* Exceeding these values may cause permanent damage. Functional operation under these conditions is not implied.
‡ Typical figures are at 25°C 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: THD is measured with “A Weight” filter.
AC Electrical Characteristics*- MH88615-1
Characteristics
1
2
Sym
REN
RL
Min
5
20
24
20
24
32
54
Typ
Max
Units
Test Comments
1 REN= 8000Ω
@ 25 Hz
Ringer Equivalence
Return Loss
dB
dB
dB
dB
200 Hz - 500 Hz
500 Hz - 2.5 kHz
2.5kHz - 3.4 kHz
300 Hz - 3.4 kHz
50 Hz - 300 Hz
300 Hz - 4 kHz
3
4
Transhybrid Loss
Longitudinal to
Metallic Balance
THL
dB
dB
* Exceeding these values may cause permanent damage. Functional operation under these conditions is not implied.
Note: Return Loss reference impedance are defined by variant type.
Transhybrid Loss is measured when terminated with network impedance.
AC Electrical Characteristics*- MH88615-3
Characteristics
1
2
3
4
Sym
REN
RL
THL
Min
4
20
20
52
Typ
Max
Units
Test Comments
4 REN= 2200Ω
@ 25 Hz
Ringer Equivalence
Return Loss
Transhybrid Loss
Longitudinal to
Metallic Balance
dB
dB
300 Hz - 3.4 kHz
300 Hz - 3.4 kHz
300 Hz - 3.4 kHz
dB
* Exceeding these values may cause permanent damage. Functional operation under these conditions is not implied.
Note: Return Loss reference impedance are defined by variant type.
Transhybrid Loss is measured when terminated with network impedance.
2-143
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