®
MH88628
Central Office SLIC
Preliminary Information
Features
•
•
•
•
•
•
•
•
•
•
•
•
Programmable gain, network balance and
impedance
Transformerless 2-4 wire conversion
Constant current with constant voltage fallback
for long loop capability
Pin compatible with MH88632, MH88620 and
MH88628
Unbalanced detection (Tip, Ring ground
sensing)
Auto ring trip with zero crossing
On-Hook transmission (ANI) capability
Compatible with requirements of CCITT,
DOC/FCC and CSA/UL
Excellent power dissipation (SIL vertical
mounting)
12/16kHz meter pulse injection control
Solid State TIP/RING reversals
Ringing amplifier
MH88628
ISSUE 5
April 1995
Ordering Information
40 Pin SIL Package
0°C to 70°C
Applications
•
•
•
On/Off Premise PBX Line Cards
DID (Direct Inward Dial) Line Cards
Central Office Line Cards
Description
The Mitel MH88628 SLIC provides all of the
functions required to interface 2-wire off premise
subscriber loops to a serial TDM, PCM, switching
network of a modern PBX. The MH88628 is
manufactured using thick-film hybrid technology
which offers high voltage capability, reliability and
high density resulting in significant printed circuit
board area savings. A complete C.O. line card can
be implemented with very few external components.
VBat
LGND
LCA
VDD
VEE
AGND
RING
RF1
RF2
TIP
TF1
TF2
Matched
Feed
Resistors
Driver
Circuitry
and
Speech
Circuit
Loop
Current
Set
Switch-hook
Threshold Set
Ring
Filter
Switch-hook
Detect
SHK
NS
UD
Unbalanced
Detection
Impedance
Network
2-4 Wire
Conversion
N1
N2
NATT
VRLY
RNGD
RD
Decoder
Circuit
Ringing
Amplifier
External
Signal
Input
Gain Adjust
SEL1 SEL2
ACRI DCRI
ESI
ESE
Z900 Z600 Z1
Z2
GRX1 GRX0 RX GTX1 GTX0 TX
Figure 1 - Functional Block Diagram
2-199
MH88628
TIP
RING
TF1
TF2
RF1
RF2
LGND
LCA
VBat
DCRI
RGND
VRLY
RD
SEL1
SEL2
ESI
ESE
AGND
NATT
N1
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
N2
Z900
Z1
Z2
TX
RX
GTX0
GTX1
GRX0
GRX1
ACRI
Z600
NS
SHK
UD
IC
IC
IC
VEE
VDD
Preliminary Information
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
Figure 2 - Pin Connections
Pin Description
Pin #
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
Name
TIP
RING
TF1
TF2
RF1
RF2
LGND
LCA
VBat
DCRI
RGND
VRLY
RD
SEL1
SEL2
ESI
ESE
AGND
NATT
Description
Tip Lead.
Connects to the “Tip” lead of subscriber line.
Ring Lead.
Connects to the “Ring” lead of the subscriber line.
Tip Feed 1.
Access point for balanced ringing. Normally connects to TF2.
Tip Feed 2.
Access point for balanced ringing. Normally connects to TF1.
Ring Feed 1.
Access point for balanced ringing. Normally connects to RF2.
Ring Feed 2.
Access point for balanced ringing. Normally connects to RF1.
Battery Ground.
VBat return path. Connected to system’s energy dumping ground.
Current Limit Set (Input).
The current limit is set by connecting an external resistor to
ground. For 30mA default current, this pin is tied to GND.
Battery Voltage.
Typically -48Vdc is applied to this pin.
DC Ringing Voltage Input.
A continuous 120Vdc is applied to this input.
Relay Driver Ground Connection.
Relay Supply Voltage Connection.
Ring Drive (Output).
Connects to ring relay coil.
Select 1 (Input).
Refer to Table 5
Select 2 (Input).
Refer to Table 5.
External Signal Input.
12/16kHz meter pulse input.
External Signal Enable.
Applies the external signal to the line.
Analog Ground.
VDD and VEE return path.
Network Balance AT+T Node.
Connects to N1 for a network balance impedance of AT&T
compromise (350Ω + 1kΩ // 210nF); the device’s input impedance must be set to 600Ω.
This node is active only when NS is at logic high. This node should be left open circuit when
not used.
2-200
Preliminary Information
Pin Description (Continued)
Pin #
20
Name
N1
Description
MH88628
Network Balance Node 1(Input).
0.1 times the impedance between pins N1 and N2 must
match the device’s input impedance, while 0.1 times the impedance between pins N1 and
AGND is the device’s network balance impedance. This node is active only when NS is at
logic high. This node may be terminated when not used (i.e., NS at logic low).
Network Balance Node 2 (Output).
See N1 for description.
Line Impedance 900Ω Node.
Connects to Z1 for a line impedance of 900Ω. This node
should be left open circuit when not used.
Line Impedance Node 1 (Input).
0.1 times the times the impedance between pins Z1 and
Z2 is the device’s line impedance. This node must always be connected.
Line Impedance Node 2 (Output).
0.1 times the times the impedance between pins Z1
and Z2 is the device’s line impedance. This node should be left open circuit when not used.
Transmit (Output).
4-Wire (AGND) referenced audio output.
Receive (Input).
4-Wire (AGND) referenced audio input.
Transmit Gain Node 0.
Connects to GTX1 for 0dB transmit gain.
Transmit Gain Node 1.
A resistor to AGND provides transmit gain adjustment.
Receive Gain Node 0.
Connects to GRX1 for 0dB gain.
Receive Gain Node 1.
A resistor to AGND provides receive gain adjustment.
AC Ringing Voltage Input.
A 1.5Vrms 20Hz signal is applied to this input.
Line Impedance 600
Ω
Node (Output).
Connects to Z1 for a line impedance of 600Ω.
This pin should be left open circuit when not used.
Network Balance Setting (Input).
The logic level at NS selects the network balance
impedance. A logic 0 enables an internal balance equivalent to the input impedance (Z
in
).
While a logic 1 enables an external balance 0.1 times the impedance between pins N1 and
AGND balanced to 0.1 times the impedance between pins N1 and N2. The impedance
between N1 and N2 must be equivalent to 10 times the input impedance (Z
in
).
Off-Hook Indication (Output).
A logic low output indicates when the subscriber equipment
has gone Off-Hook.
Unbalance Detect (Output).
A log IC low output indicates when the DC current flow in the
Tip and Ring leads is unbalanced, indicating that the subscriber equipment has grounded
the Ring lead.
Internal Connection.
These pins are internally connected and must be left open
Negative Supply Voltage.
-5V dc.
Positive Supply Voltage.
+5V dc.
21
22
23
24
25
26
27
28
29
30
31
32
33
N2
Z900
Z1
Z2
TX
RX
GTX0
GTX1
GRX0
GRX1
ACRI
Z600
NS
34
35
SHK
UD
36,37,38
IC
VEE
VDD
39
40
2-201
MH88628
Absolute Maximum Ratings*
Parameter
1
Supply Voltage
Sym
V
Bat
V
DD
V
EE
V
DCRI
T
S
Min
+0.3
-0.3
+0.3
-0.3
-40
Max
65
6
-6
140
+125
Units
V
V
V
V
°C
Preliminary Information
Comments
With respect LGND
2
Storage Temperature
* Exceeding these values may cause permanent damage. Functional operation under these conditions is not implied.
Recommended Operating Conditions
Parameter
1
Supply Voltage
Sym
V
Bat
V
DD
V
EE
T
OP
Min
-44
4.75
-4.75
0
Typ*
-48
+5.0
-5.0
20
90
17
V
DCRI
110
120
33
130
Max
-60
5.25
-5.25
70
Units
V
V
V
°C
Vrms
Hz
Vdc
Comments
2
3
Operating Temperature
AC Ring Generator
Voltage
Frequency
4
DCRI
Input DC Voltage
* Typical figures are at 25
°
C with nominal
+
5V supplies for design aid only.
DC Electrical Characteristics
‡
Characteristics
1
Operating Loop Current
Sym
I
Loop
I
Loop
I
Loop
I
Loop
I
Bat
I
Bat
I
DD
I
EE
3
4
SHK
UD
5
6
SEL1
SEL2
ESE
NS
Low level Output Voltage
High Level Output Voltage
Low Level Input Voltage
High Level Input Voltage
High Level Input Current
Low Level Input Current
V
OL
V
OH
V
IL
V
IH
I
IH
I
IL
0.5
3.7
0.8
2.4
20
20
V
V
V
V
µA
µA
V
IH
=5.0V
V
IL
=0.0V
I
OL
= 400µA
I
OH
= 40µA
Power Dissipation
PD
O
PD
1
Min
16
30
±2
32
2
25
25
2
300
Typ*
45
Max
Units
mA
mA
mA
mA
mA
mA
mA
mA
W
mW
Test Conditions
R
Loop
=0Ω
2300Ω VBat =-48V
R
Loop
=0Ω, LCA -
GND
R
Loop
=0 (off Hook),
LCA=GND
R
Loop
= open (On-
Hook)
On-hook or Off-Hook
On-Hook or Off-Hook
Active
Standby/Idle
Var in loop current from nominal
2
Operating Currents
‡ 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.
2-202
Preliminary Information
AC Electrical Characteristics
‡
Characteristics
1
2
3
4
TX Gain
RX Gain
Ringing Capability
On-Hook Transmission
Signal Input Level
Gain
External Signal Output Level
1.75
Sym
Min
Typ*
0
0
5
2.0
6
2.25
Max
Units
dB
dB
REN
V
rms
dB
V
rms
MH88628
Test Conditions
externally adjustable
externally adjustable
V
Bat
=-48V
T-R load = 10kΩ min.
V
Bat
= -48V, T-R load=
200Ω LCA=0V, Zo-600Ω,
Gain=0dB
Dial Pulse Detection
5
6
7
8
9
SHK Rise Time
Fall time
2-Wire Termination
Impedance
Off-Hook Detect Threshold
2-Wire Return Loss
t
R
t
F
1
1
600/
900
10
20
20
20
58
53
40
ms
ms
Ω
Selectable
mA
dB
dB
dB
dB
dB
mA
300 to 500Hz
500 to 2500Hz
2500 to 3400Hz
200-1000Hz
1kHz - 3k4Hz
20mA per lead
10
Longitudinal Balance
Longitundinal to Metallic
Longitudinal Current
Capability
Idle channel Noise
Rx to T-R
T-R to Tx
N
CR
N
CX
THL
I
UB
11
12
8
12
22
40
10
4
90
17
100
+0.1
+0.05
33
dBrnC
dBrnC
dB
mA
dBm
Vrms
Hz
ms
dB
dB
dB
0dB at T-R, 1kHz
300-3400Hz
1kHz, 100mVpp
T-R=600Ω, V
Bat
=-48V
200-3400Hz
13
14
15
16
17
18
19
20
21
Transhybrid Loss
Unbalanced Detect Threshold
Analog Signal Overload Level
At Tip and Ring
Ringing Signal Voltage
Ringing Frequency
Ring Trip Delay
Absolute Gain, Variation
Relative Gain, reference to
1kHz
Power Supply Rejection Ratio PSRR
V
Bat
24
V
DD
24
V
EE
24
* Typical figure are at 25°C with nominal
+
5V supplies and are for design aid only.
‡ AC Electrical Characteristics are over recommended operating conditions unless otherwise stated.
Notes:
Impedance set by external network of 600Ω or 900Ω default.
External network for test purposes consists of 2200Ω + 8200Ω // 11.5nF between pins Z1 and Z2, the equivalent Zin has 1/10
th
the impedance
and is equivalent o 220Ω+820Ω // 115nF.
Test condition uses a Zin value of 600Ω, 900Ω and the above external network.
Test conditions use a transmit and receive gain set to 0dB default and a Zin value of 600Ω unless otherwise stated.
“Ref” indicates reference impedance which is equivalent to the termination impedance.
“Net” indicates network balance impedance.
Refer to Table 1, 2 for TX, RX gain adjustment.
2-203
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