2-83
Features
Programmable line impedance matching
Internal complex impedance networks
Transformerless 2-4 wire conversion
Programmable transmit/receive gain
Accommodates worldwide transmission
standards
Operates with a wide range of battery voltages
Adjustable constant current battery feed
Overvoltage and short circuit protection
Switch hook and ground button detection
Ring trip filter and relay driver
Low power consumption
High power dissipation capability during fault
conditions
Applications
Line interface for:
PABXs
Control Systems
Key Telephone Systems
Central Office Equipment
Description
The MH88600 is a SLIC (Subscriber Line Interface
Circuit) which provides all of the BORSCH functions
of Battery Feed, Overvoltage Protection, Ringing
Feed, Line Supervision and 2-4 Wire Hybrid
conversion. In addition, the device matches the
many different line impedances specified by
regulatory authorities of around the world.
Figure 1 - Functional Block Diagram
Tip Drive
Over Voltage &
Short Circuit
Protection
Ring Drive
Constant
Current
Battery Feed
Impedance Matching Network
2-4 Wire
Hybrid
Circuit
Gain Adjust
Ring Trip Filter
Line Supervision
Relay Driver
TF1
TF2
TIP
RING
RF1
RF2
PG2
PG4
TX
PG3
PG1
EGB
SHK
RC
RD
VRR
GNDA
VDD
VE
E
Vb
a
t
GNDBa
t
ZN7.....................ZN1
ZN13.................ZN8
ZN0
LCA
VREF
ZN14
ISSUE 7
April 1995
Ordering Information
MH88600
40 Pin DIL Hybrid
0
C to 70
C
MH88600
Global SLIC
Preliminary Information
2-84
MH88600
Preliminary Information
Figure 2 - Pin Connections
Pin Description
Pin #
Name
Description
1
No pin at this location.
2
V
Bat
Battery Supply Voltage (Negative).
3
RF1
Ring Feed (1): Connect to relay contact. See Figures 6 & 7.
4
RF2
Ring Feed (2). Connect to relay contact. See Figures 6 & 7.
5
RING
Connects to the "Ring" or "B" lead of the telephone line.
6
TIP
Connects to the "Tip" or "A" lead of the telephone line.
7
I/C
Internal Connection.
8
GND
Bat
Battery Supply Ground (Positive): Connect to System Ground
9
TF2
Tip Feed (2). Connect to TF1 for unbalanced ringing, see Figure 6. Connect to relay
contact for balanced ringing, see Figure 7.
10
TF1
Tip Feed (1). Connect to TF2 for unbalanced ringing, see Figure 6. Connect to relay
contact for balanced ringing, see Figure 7.
11
GNDA
Analog Ground: Normally connected to System Ground.
12
V
EE
Negative Power Supply Voltage: Normally -5V.
13
V
DD
Positive Power Supply Voltage: Normally +5V.
14
V
RR
Ringing Relay Clamp Diode: Connect to relay coil and to relay supply voltage
(Positive). For +5V relay, connect to VDD.
15
RC
Ring Control (Input): A logic high will activate the Ring Relay Drive if SHK is high.
16
RD
Ring Relay Drive (Output). Connect to relay coil. A logic low will activate the relay by
sinking current from VRR through the relay coil.
17
LCA
Loop Current Adjust (Input): Loop current is proportional to the voltage at this input.
Normally connected to VRef
18
SHK
Switch Hook Detect (Output): A logic low indicates an off-hook condition.
19
EGB
Earth Ground Button (Output): A logic low indicates a grounded Ring lead condition.
20
V
Ref
Voltage Reference (Output): Normally connected to LCA for default loop current.
ZN13
ZN12
ZN11
ZN10
ZN9
ZN8
ZN7
ZN6
ZN5
ZN4
ZN3
ZN2
ZN1
TX
PG3
PG1
PG2
PG4
ZN0
ZN14
VBat
RF1
RF2
RING
TIP
IC
GNDBat
TF2
TF1
GNDA
VEE
VDD
VRR
RC
RD
LCA
SHK
EGB
VRef
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
40
39
38
37
36
35
34
33
32
31
30
29
28
27
26
25
24
23
22
21
2-85
Preliminary Information
MH88600
.
21
ZN0
Impedance Node 0. Connect to external network for impedance (Z
in
) setting. See Table
2 and Figure 8.
22
PG4
Programming 4 (Input). Used for programmable gain and for default gain. Used as 4-
Wire Receive Input for default gain. See Table 3 and Figure 4 and 5.
23
PG2
Programming 2 (Input). Used for programmable gain. Used with resistor for 4-Wire
Receive Input. See Table 3 and Figure 4.
24
PG1
Programming 1 (Input). Used for programmable gain. See Table 3 and Figure 4.
25
PG3
Programming 3 (Input). Used for programmable gain and for default gain. See Table 3
and Figure 4 and 5.
26
TX
4-Wire Transmit Output:
27
ZN1
Impedance Node 1: Connect to other Impedance Nodes for impedance (Z
in
) setting,
see Table 1. Or, connect to external network for impedance (Z
in
) setting, see Table 2 and
Figure 8.
28
ZN2
Impedance Node 2: Connect to other impedances Nodes for impedance (Z
in
) setting.
See Table 1.
29
ZN3
Impedance Node 3: As per ZN2. See Table 1.
30
ZN4
Impedance Node 4: As per ZN2. See Table 1
31
ZN5
Impedance Node 5: As per ZN2. See Table 1
32
ZN6
Impedance Node 6: As per ZN2. See Table 1
33
ZN7
Impedance Node 7: As per ZN2. See Table 1
34
ZN8
Impedance Node 8: As per ZN2. See Table 1
35
ZN9
Impedance Node 9: As per ZN2. See Table 1
36
ZN10
Impedance Node 10: As per ZN2. See Table 1
37
ZN11
Impedance Node 11: As per ZN2. See Table 1
38
ZN12
Impedance Node 12: As per ZN2. See Table 1
39
ZN13
Impedance Node 13: As per ZN2. See Table 1
40
ZN14
Impedance Node 14: Connect to external network for impedance (Z
in
) setting. See
Table 2 and Figure 8.
Pin Description (Continued)
Pin #
Name
Description
MH88600
Preliminary Information
2-86
Functional Description
The BORSH Functions
The MH88600 performs all of the BORSH functions;
Battery Feed, Overvoltage Protection, Ringing,
Supervision and Hybrid.
Battery Feed
The MH88600 provides the loop with constant DC
current to power the telephone set. The voltage
(negative) applied at the LCA pin determines the
magnitude of the lop current.
I
Loop
= 3.731 x VLCA mA (2mA)
Either the internal (V
Ref
) or an external negative
voltage reference may be used to set the loop
current.
Overvoltage Protection
The MH88600 is protected from short term (20ms)
transients (+250V) between Tip and Ring, Tip and
ground, and Ring and Ground. However, additional
protection circuitry may be needed depending on the
regulatory requirements which must be met.
Normally, simple external shunt protection as shown
in Figures 6,7 and 8 is all that is required.
Ringing
The MH88600 has the capability to accommodate
both balanced and unbalanced ringing sources.
Refer to Figure 7 for the Balanced Ringing Circuit
and Figure 6 for the Unbalanced Ringing Circuit.
Supervision
The MH88600 is capable of detecting both Ground
Button and Switch Hook conditions. The Ground
Button detection (a logic low at the EGB output)
operates when an imbalance in Tip and Ring DC
current exceeds an internal threshold level caused
by a grounded Ring Lead. Use of the EGB output is
restricted to the off-hook condition of the telephone.
The Switch Hook detection operates (a logic low at
the SHK output) when the DC loop current exceeds
an internal threshold level.
The Ring Trip Detection Circuit prevents false off-
hook detection due to the current associated with the
AC ringing voltage and also due to the large current
transients when the ring voltage is switched in and
out. In addition, the circuit prevents connection of the
ringing source during off-hook conditions.
Hybrid
The 2-4 Wire Hybrid circuit separates the balanced
full duplex signal at Tip and Ring of the telephone
line into receive and transmit ground referenced
signals at RX (receive) and TX (transmit) of the
SLIC. The Hybrid also prevents the input signal at
RX from appearing at TX. The degree to which the
Hybrid prevents the RX signal from appearing at TX
is specified at transhybrid loss.
Tip-Ring Drive Circuit
The audio input ground referenced signal at RX is
converted to a balanced output signal at Tip and
Ring. The output signal consists of the audio signal
superimposed on the DC Battery Feed Constant
Current. The Tip-Ring Drive Circuit is optimised for
good 2-Wire longitudinal balance.
Short Circuit Protection
The MH88600 is protected from long term (infinite)
short circuit conditions occurring between Tip and
Ring, Tip and Ground, Ring and Ground, and Ring
and Battery. The current is limited to the same value
as the Constant Current Battery Feed.
Programmable Line Impedance
The MH88600's Tip-Ring (Z
in
) impedance can be
matched to the different impedances specified by
different telephone administrations worldwide. This
is accomplished by either linking specific pins as
specified in Table 1, or by adding external
components as shown in Figure 8 and Table 2.
Programmable Transmit & Receive Gain
Transmit gain (TX to Tip-Ring) and Receive Gain
(Tip-Ring to RX) can be programmed by connecting
external resistors as indicated in Figure 4 and Table
3. Alternatively, the default Receive Gain of -4d Band
Transmit Gain of +4dB can be obtained by
connecting pins as shown in figure 5 and Table3.
Note that RX is not a pin on the SLIC. The RX
terminal will be either PG4 or the connection to the
receive gain programming resistor RRX shown in
Figure 4 and Figure 5.
2-87
Preliminary Information
MH88600
Figure 3a - Loop Current vs.Maximum Loop Current
Figure 3b - Maximum Loop Length vs Battery voltage
VBat = -24V
VBat =-48V
VBat = -24V
VBat = -48V
Loop Detect Threshold
Maximum
Loop
Length (
)
500
1000
1500
2000
25
20
15
10
5
Loop Current (mA)
2000
1800
1600
1400
1200
1000
800
600
400
200
16 20
24
28
32
36
40
44
48
52
56
60
64
Maximum Loop Length (
)
ILoop = 20mA
ILoop = 25mA
VBAT (V)
2-88
MH88600
Preliminary Information
Absolute Maximum Ratings*
- Voltages are with respect to AGND.
* Typical figures are at 25C and are for design aid only: not guaranteed and not subject to production testing.
Parameters
Sym
Min.
Max
Units
1
DC Supply Voltages
(GNDA = GND
Bat
)
V
DD
-0.3
15
V
V
EE
+0.3
-15
V
V
Bat
+0.3
-80
V
V
RR
-0.3
40
V
2
Storage Temperature
T
S
-55
125
C
3
Power Dissipation
P
D
4
W
.
* Exceeding these values may cause permanent damage. Functional operation under these conditions is not implied.
Recommended Operating Conditions
Characteristics
Sym
Min.
Typ
*
Max
Units
Comments
1
Operating Supply Voltage
V
DD
4.75
5.0
5.25
V
V
EE
-5.25
-5.0
-4.75
V
V
Bat
-72
-48
-24
V
V
RR
5
24
V
2
Operating Temperature
T
OP
0
70
C
2-89
Preliminary Information
MH88600
* Typical figures are at 25C and are for design aid only: not guaranteed and not subject to production testing.
DC Electrical Characteristics are over recommended operating conditions unless otherwise stated.
See Figures 3a and 3b.
DC Electrical Characteristics
Parameters
Sym
Min.
Typ*
Max
Units
Test Conditions
1
Supply Current
I
DD
I
EE
I
Bat
8.5
5.0
12.0
10.0
4.8
mA
mA
mA
R
Loop
=Open Cct,
V
Bat
= -48V
2
Power Consumption
PC
330
755
1556
mW
mW
mW
Standby
R
Loop
=1200
R
Loop
=0
V
Bat
=-48V
3
Constant Current
Battery Feed
I
Loop
I
Loop
18
21
20
25
22
30
mA
mA
LCA=-5.4V when R
Loop
-0
LCA=linked to V
Ref when
R
Loop
=0
4
Operating Loop
Resistance
R
Loop
2000
800
1560
600
V
Bat
=-48V, I
Loop
=20mA
V
Bat
=-48V, I
Loop
=20mA
V
Bat
=-48V, I
LLoop
=25mA
V
Bat
=-48V, I
Loop
=25mA
5
Off-Hook Detect Threshold
SHK
th
10
mA
6
GND Button Detect
Threshold
EGB
th
10
mA
7
Ring GND Over-Current
Protection
32
41
mA
8
SHK
&
EGB
Low Level Output Voltage
High Level Output Voltage
V
OL
V
OH
2.4
0.4
V
V
No Load
9
Sink Current
Source Current
I
OL
I
OH
160
390
V
OL
=0.8V
V
OH
=-0.2V
10
RC
Low Level Input Voltage
High Level Input Voltage
V
IL
V
IH
4.0
0.4
V
V
11
High Level Input Current
I
IH
1.5
mA
V
IH
= V
DD
12
RD
Sink Current
I
RLY
65
mA
13
Clamp Diode Current
I
CD
65
mA
14
V
Ref
Internal Reference
-7.4
-6.7
-6.0
V
LCA linked to V
Ref
2-90
MH88600
Preliminary Information
AC Electrical Characteristics are over recommended operating unless otherwise stated.
* Typical figures are at 25 C and are for design aid only: not guaranteed and not subject to production testing.
AC Electrical Characteristics
-
Voltages are with respect to GNDA unless otherwise stated.
Characteristics
Sym
Min.
Typ
*
Max
Units
Test Conditions
1
Ringer Voltage
VR
105
V
rms
See Fig 6
2
Ringer Equivalence No.
REN
5
3
Ring Trip Detect Time
200
ms
4
Input Impedance at PG4
at VRX
Z
RX
112
RRX
k
See Fig 5
See Fig 4
5
Output Impedance at TX
Z
TX
3
6
Gain 2-Wire to TX: Fixed Gain
Programmable Range
Frequency Response Gain
relative to Gain @ 1kHz
300Hz
600Hz and 2400Hz
3000Hz
3400Hz
A TX
+3.5
+4
+4.5
dB
Input 1.0V at 1kHz See Fig 5
RTX
-12
+6
dB
See Figure 4
A
R
TX
-0.75
-0.1
-0.3
-0.75
0.1
0.1
0.1
0.1
dB
dB
dB
dB
Input 1.0V
600
2-Wire Impedance
7
Gain RX to 2-Wire: Fixed Gain
Programmable Range
Frequency Response Gain
relative to Gain @ 1kHz
300Hz
600Hz and 2400Hz
3000Hz
3400Hz
ARX
-4.5
-4
-3.5
dB
Input 1.0V at 1kHz See Fig 5
RRX
-12
+6
dB
See Figure 4
A
R
RX
-0.75
-0.1
-0.3
-0.75
0.1
0.1
0.1
0.1
dB
dB
dB
dB
Input 1.0V
600
2-Wire Impedance
8
2-Wire Return Loss
RL
20
18
26
dB
dB
Input 1.0V, 200Hz to 3.4kHz
Input 1.0V, 3.4kHz to 4kHz
9
2-Wire Input Impedance
Z
IN
See Table 1
10
Transhybrid Loss
THL
20
40
dB
Input 1.0V at 300Hz to
3400Hz at PG4
11
Longitudinal Balance
52
41
dB
dB
40 - 3400Hz
3400-4000Hz
12
Total Harmonic Distortion
at TX
at 2-Wire
THD
0.1
0.1
1.0
1.0
%
%
Input 1.0V at 1kHz at 2-Wire
Input 1.0V at 1kHz at PG4
13
Common Mode Reject Ratio
CMRR
40
CCITT 0.121
14
Idle Channel Noise at TX
(0dB gain)
Idle Channel Noise at 2-Wire
(0dB gain)
Nc
Np
Nc
Np
13
-78
11
-80
18
-73
16
-75
dBrnC
dBrnp
dBrnC
dBrnp
15
Power Supply Reject Ratio V
DD
V
EE
V
BAT
PSRR
25
20
30
dB
dB
dB
Ripple 1Vpp 1kHz
Measure 2-Wire or TX
16
Dial Pulse Distortion
(SHK High to Low Time)
t
d
0.4
1
ms
2-Wire loop at 1.2k
2-91
Preliminary Information
MH88600
Table 1: Impedance Matching with Jumpers
Note 1: The above impedances are as suggested by references: BS6305 (UK), REG3 (Australia), Proposed NET4, FCC Part 68 and
recommendations by the various Administrations. Confirm your impedance requirements before proceeding.
Note 2: All links to ZN1 should be as short as possible.
Table 2: Impedance Matching with External Components
Note 1: The above impedances are as suggested by reference CCITT Q.522. Confirm your impedance requirements before proceeding.
Note 2: For Rs, Rp & C calculations, G is set to 10, R is set to 5656.8
,
refer to figure 8 for additional information.
Table 3: Transmit and Receive Gain Programming
Note 1: See Figures 4 and 5 for additional details.
Note 2: Overall gain refers to the receive path of PCM to 2-Wire, and to transmit path of 2-Wire to PCM.
Zin Code
Zin 2-Wire Input Impedance
Administration
ZN1 Link to:
ZN8 Link to:
1
600
600
---
ZN7
---
2
UK
370
+ 620
// 310nF
United Kingdom
ZN6
ZN13
3
D
220
+ 820
// 310nF
Germany, Austria
ZN5
ZN12
4
NA
350
+ 1000
// 310nF
Canada, USA
ZN4
ZN11
5
F
210
+880
// 310nF
France
ZN3
ZN10
6
N
120
+ 820
// 310nF
Norway
ZN2
ZN9
7
A
220
+ 820
// 310nF
Australia
Use D Code
Use D Code
Zin Code
Zin 2-Wire Input Impedance
Administration
Rs
Rp
Cp
1
---
600
+ 2.1
6
F
---
6k
1M
216nF
2
ATT
900
+ 2.16
F
AT&T
9k
1M
216nF
3
NTT
600
+ 1.0
F
NTT
6k
1M
100nF
4
NZ
370
+ (620
// 220nF)
New Zealand
3.7k
6.2k
22nF
Transmit Gain
(dB)
RTX Resistor
Value (
)
Notes
+5.62
270k
+4.0
No Resistor
Results in 0dB overall gain when used with Mitel A-law codec (ie MT8965)
+3.69
216k
Results in 0dB overall gain when used with Mitel
-law codec (ie MT8964)
+2.1
180k
0.0
141k
-3.0
100k
Transmit Gain
(dB)
RTX Resistor
Value (
)
Notes
+6.6
33.1k
+0.0
70.7k
-3.0
100k
-3.69
108k
Results in 0dB overall gain when used with Mitel A-law codec (ie. MT8964)
4.0
No Resistor
Results in 0dB overall gain when used with Mitel
-law codec (ie MT8965)
-6.5
150k
2-92
MH88600
Preliminary Information
Figure 4 - Configuration of MH88600 for Gain Programming
Figure 5 - Configuration of MH88600 for Default Gains
MH88600
PG1
TX
PG3
PG4
PG2
GNDA
V
TX
TRANSMIT
V
RX
RECEIVE
RX
R
RX
RTX
24
26
25
22
23
11
Transmit Gain =
V
TIP
-
RING
= R
TX
(k
)x0.007071
Receive Gain = V
TIP - RING
V
RX
70.71
=
R
RX
(k
)
Note: PG3 and PG4 pins should be left open circuit. See Table 3.
TX
V
Tx
MH88600
PG1
TX
PG3
PG4
PG2
GNDA
V
TX
TRANSMIT
V
RX
RECEIVE
RX
26
25
22
23
11
Transmit Gain =
V
TX
V
TIP - RING
= +4dB
Receive Gain = V
TIP - RING
V
RX
-4dB
=
Note: PG2 pins should be left open circuit. See Table 3.
TX
24
2-93
Preliminary Information
MH88600
Figure 6- Typical Application Circuit
ZN13
ZN8
ZN6
ZN1
TF2
TF1
TIP
RF2
RF1
RD
VRR
RC
LC
A
VR
e
f
VD
D
VE
E
VB
a
t
G
NDA
GN
D
Ba
t
SHK
EGB
PG4
TX
PG3
RING
39
34
32
27
25
26
22
19
18
8
11
2
12
13
17
15
C1
C2
+5V
-5V
14
16
3
4
5
6
10
9
RV1
K1
K1
K1
+ve
RELAY
SUPPLY
RINGING
CONTROL
TO MDF and
SUBSCRIBER SET
MH88600
~
90VRMS
20Hz
RV2
RINGING
GENERATOR
20
VX
VR
CODEC
RV1,RV2 - V150LA 150Vrms
13J (10/1000)
C1,C2 - 10
F/10V Electrolytic or Tantalum
K1 - Relay E/M, 12V, 1Form C
2-94
MH88600
Preliminary Information
Figure 7 - Application Circuit for Balanced Ringing
ZN13
ZN8
ZN6
ZN1
TF2
TF1
TIP
RF2
RF1
RD
VRR
SHK
EGB
PG4
TX
PG3
RING
39
34
32
27
25
26
22
19
18
14
16
3
4
5
6
10
9
30k
0.15W
K1
RV1
RV2
K1
K1
+ve
RELAY
SUPPLY
RINGING
CONTROL
TO MDF and
SUBSCRIBER SET
RINGING
GENERATOR
MH88600
~
~
20Hz
-48V
+
-
45V
RMS
45 V
RMS
20Hz
RC
LC
A
VR
e
f
VD
D
VEE
VB
a
t
G
NDA
GN
D
Ba
t
8
11
2
12
13
17
15
C1
C2
+5V
-5V
20
2-95
Preliminary Information
MH88600
Figure 8 - Using an External Network to Match any Zo
ZN13
ZN8
ZN6
ZN1
TF2
TF1
TIP
RF2
RF1
RD
VRR
SHK
EGB
PG4
TX
PG3
RING
40
27
21
25
26
22
19
18
14
16
3
4
5
6
10
9
RV1
K1
K1
K1
+ve
RELAY
SUPPLY
RINGING
MH88600
~
90VRMS
20Hz
RV2
RINGING
GENERATOR
VX
VR
CODEC
External Network
C3
Zo
C1=C2=10
F, 10V Electrolytic
or tantalum
C3=1nF, 250V, 20%
C3 is recommended to
improve stability when
used on loop lengths less
than 500
total or used
with active loads
Z=G x Zo
R=565.68 x G
G may be chosen to
suit preferred component
values (useful for
capacitive elements);
resistive elements should
have values in the range
of 1k to 1M
. Typical values
See Table 2 for external
network examples.
Set Rp=1M
for networks
not specifying an Rp
Z
Rs
Cp
Rp
Z
R
are G = 10
=
CONTROL
RC
LC
A
VR
e
f
VD
D
VE
E
VB
a
t
G
NDA
GN
D
Bat
8
11
2
12
13
17
C1
C2
+5V
-5V
20
15
2-96
MH88600
Preliminary Information
Figure 9 - Mechanical Data
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MH88600
Note 1
Notes:
1) Pin 1 not fitted.
2) Row pitch is to the centre of the pins.
3) All dimensions are typical and in inches (mm).
4) Seated Height
0.10 + 0.01
(2.54 + 0.25)
0.09
(2.3)
0.260
(6.6)
0.3
(7.62)
0.020 + 0.002
(0.51 + 0.051)
1.0
(25.4)
Note 2
2.0
(50.8)
5) Not to scale
Note 4
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