MH88634K [MITEL]
Central Office Interface Circuit Preliminary Information; 中央办公厅接口电路的初步信息
| 型号： | MH88634K |
| 厂家： | 
MITEL NETWORKS CORPORATION |
| 描述： | Central Office Interface Circuit Preliminary Information |
| 文件： | 总8页 (文件大小：69K) |
| 中文： | 中文翻译 | 下载： | 下载PDF数据表文档文件 |
MH88634K
Central Office Interface Circuit
Preliminary Information
ISSUE 3
April 1995
Features
Ordering Information
•
•
•
Loop Start Trunk Interface
600 Ohm input impedance
Line state detection outputs:
- forward loop
MH88634K
21 Pin SIL Package
0°C to 70°C
- reverse loop
- ringing voltage
- service out
Description
•
•
•
Transformerless 2W to 4W conversion
One loop start relay driver
+/- 5V operation
The Mitel MH88634K Central Office Trunk Interface
circuit provides a complete audio and signalling link
between audio switching equipment and a central
office. The functions provided by the MH88634K
include 2-4 Wire conversion, 600 Ohm input
impedance and network balance. The device is
fabricated as a thick film hybrid incorporating various
technologies for optimum circuit design and very
high reliability.
Applications
Interface to Central Office for:
•
•
•
•
•
•
•
PABX
Key Telephone Systems
Channel Bank
Voice Mail
Terminal Equipment
Digital Loop Carrier
Optical Multiplexer
RING
TIP
VDD VEE AGND RV
FL
RL
SO
Dummy
Ringer
Status
Detection
XLA
Loop
Termination
XLB
XLC
XLD
Rx
Tx
Receive
Gain
2 - 4 Wire Hybrid
LRC
LRD
Loop Relay
Driver
Transmit
Gain
Impedance
Matching
Network
Balance
VRLY
RGND
Figure 1 - Functional Block Diagram
2-261
MH88634K
Preliminary Information
1
2
3
4
5
6
7
8
TIP
RING
XLA
XLD
XLB
XLC
IC
IC
IC
9
10
11
12
13
14
15
16
17
18
19
20
21
SO
Rx
VEE
Tx
RV
FL
RL
VDD
AGND
LRC
VRLY
LRD
Figure 2 - Pin Connections
Description
Pin Description
Pin #
Name
1
2
3
TIP
RING
XLA
Tip Lead. Connects to the “Tip” lead of the central office
Ring Lead: Connects to the “Ring” lead of the central office
Loop Relay Contact A:. Connects to XLB through the Loop relay (K1) contacts when the
relay is activated. This operates the internal active termination circuitry.
4
5
6
XLD
XLB
XLC
Loop Relay Contact D: See XLC for description
Loop Relay Contact B: See XLA for description
Loop Relay Contact C: Connects to XLD through the loop relay (K1) contacts when the
relay is activated. This operates the internal active termination circuitry.
7
8
IC
IC
Internal Connection: This pin is internally connected and must be left open.
Internal Connection.: This pin is internally connected and must be left open.
Internal Connection: This pin is internally connected and must be left open.
9
IC
10
SO
Service Out Detect (Output). A logic low indicates that the central office “Tip” and “Ring”
are out of service.
11
12
13
14
Rx
VEE
Tx
Receive (Input): 4-Wire ground (AGND) referenced audio input.
Negative Supply Voltage. -5V
Transmit (Output). 4-Wire ground (AGND) referenced audio output.
RV
Ring Voltage Detect (Output). A logic low indicates that ringing voltage is across the Tip
and Ring leads. Note that this output toggles at the ringing cadence and not at the ringing
frequency.
15
16
FL
RL
Forward Loop Detect (Output). In the on-hook state, a logic low output indicates that
forward loop battery is present. In the off-hook state, a logic low indicates that forward loop
current is present
Reverse Loop Detect (Output): In the on-hook state, a logic low output indicates that
reverse loop battery is present. In the off-hook state, a logic low output indicates that reverse
loop current is present. Reverse loop refers to the Tip lead negative respect to the Ring lead.
2-262
Preliminary Information
MH88634K
Pin Description (Continued)
Pin #
Name
Description
17
18
19
VDD
Positive Supply Voltage:. +5V
AGND Analog Ground: 4-wire ground. Connected to system ground.
LRC
Loop Relay Control (Input): A logic high activates the Loop Relay Driver output (LRD). The
Loop Relay activates internal circuitry which provides a DC termination across Tip and Ring.
Used for line seizure and dial pulsing.
20
21
VRLY
LRD
Relay Positive Supply Voltage: Typically +5V. Connects to the relay coil and the relay
supply voltage
Loop Relay Drive (Output): Connects to the Loop Relay Coil. A logic low activates the
relay. An internal clamp diode from VRLY to LRD is provided.
Functional Description
Forward loop and reverse loop detect - the FL output
provides a logic low when either forward loop battery
or forward loop current is detected (ring lead voltage
negative with respect to tip lead). The RL output
provides a logic low when either reverse loop battery
or reverse loop current is detected (tip lead voltage
negative with respect to ring lead).
The MH88634K is a COIC (Central Office Interface
Circuit) used to interface the Central Office 2-Wire
Analog Trunks. The COIC provides a Loop Start
interface function.
Incoming analog (voiceband) signals from the 2-Wire
circuit are applied differentially across Tip and Ring,
the output of which is applied to the 2 to 4 wire
converter with a fixed gain to the Tx output.
Service Out detect - the SO output will detect the
loop current between 5mA to 10.13 mA as “out of
service” during the DC termination. The Central
Office applies -48V battery to the line but limits the
loop current to this range to indicate the line is out of
service. FL and RV outputs will not go low is the loop
current is less than 12.5mA.
The outgoing analog signals are applied to Rx. The
audio signals undergo 4 to 2 wire conversion with a
fixed gain, and are differentially applied to Tip and
Ring.
Line Impedance
DC Loop Termination
The input impedance of the MH88634K is 600 ohms.
The network balance is also set at 600 ohm to
maximize the Transhybrid Balance.
The line is provided with an active DC load
termination when a logic high is applied to the LRC
(Loop Start Relay) input. The termination is similar to
a DC resistance of less than 275 ohms. An external
relay is used to activate internal circuitry which
switches the termination in and out of the loop. This
is used for both seizing the line as well as generating
dial pulses.
Transmit and Receive Gain
Transmit Gain (Tip-Ring) is set at 0dB and Receive
Gain (Rx to Tip-Ring) is set at -2dB.
Supervision Features
The supervision circuitry provides the signalling
status outputs. The ringing voltage, forward current,
reverse current and Service Out. Ringing Voltage
detect - the RV output provides a logic low when
ringing voltage is detected. This sector includes a
ringing filter which ensures that the output toggles at
the ringing cadence and not at the ringing frequency.
Typically, this output goes low 50ms after the ringing
voltage is applied and remains low for 50ms after
ringing voltage is removed.
2-263
MH88634K
Preliminary Information
†
DC Electrical Characteristics
Characteristics
Sym
Min
Typ*
Max
Units
Test Conditions
1
Supply Current
IDD
IEE
0.5
0.5
13
13
mA
mA
2
3
Power Consumption
PC
137
0.5
mW
V
VBAT not connected
IOL = 4mA
FL
RL
SO
RV
Low Level Output Voltage
VOL
High Level Output Voltage
VOH
3.7
V
IOH = 100µA
4
5
6
LRD
Sink Current, Relay to VDD
Clamp Diode Current
IOL
ICD
100
150
mA
mA
VOL = 0.35V not
continuous
LRC
Low Level Input Voltage
High Level Input Voltage
VIL
VIH
0.8
V
V
2.0
High Level Input Current
Low Level Input Current
IIH
IIL
40
40
µA
µA
VIH = 5.0V
*
Typical figures are at 25°C with nominally +5V supplies and are for design use only.
† DC Electrical Characteristics are over recommended operating conditions unless otherwise stated.
Absolute Maximum Ratings* Voltages are with respect to AGND
Parameters
Sym
Min
Max
Units
1
DC Supply Voltages
VBAT
VDD
VEE
0
-0.3
0.3
-60
7
-7
V
V
V
2
3
DC Ring Relay Voltage
Storage Temperature
VVRLY
-0.3
-55
7
V
T
+125
°C
S
* Exceeding these values may cause permanent damage. Functional operation under these conditions is not implied.
Recommended Operating Conditions
Parameters
Symbol
Min
Typ*
Max
Units
Comments
1
DC Supply Voltages
VDD
VEE
4.75
-4.75
5.0
-5.0
5.25
-5.25
V
V
2
3
DC Ring Relay Voltage
Operating Temperature
VVRLY
TOP
5.0
15
70
V
0
°C
* Exceeding these values may cause permanent damage. Functional operation under these conditions is not implied.
2-264
Preliminary Information
MH88634K
Loop Electrical Characteristics*
†
Characteristics
Symbol
Min
Typ
Max
Units
Test Conditions
1
2
3
Ringing Voltage
VR
40
16
90
20
1
130
33
2
Vrms
Hz
Ringing Frequency
Ringer Equivalence number
REN
0.5
Dummy Ringer is 17K
in series with 330nF.
Type A ringing
4
5
6
7
Operating Loop Current
Operating Loop Resistance
Off-Hook DC Resistance
15
0
70
1800
275
10
mA
Ω
@ 20mA, -42.5V
@ 20mA
250
Ω
Leakage Current
(Tip-Ring to AGND)
mA
@ 1000Vac
50 or 60 Hz
8
9
FL Threshold
Tip-Ring (On-hook)
Tip-ring Current (Off-Hook)
+30
12.5
+40
15
Vdc
mA
LRC = 0v
LRC = 5V
RL Threshold
Tip-Ring (On-Hook)
Tip-Ring current (Off-Hook)
-30
-12.5
-40
-15
Vdc
mA
LRC = 0v
LRC = 5V
10
-10.13
-12.4
mA
VBAT = -48V
SO Detect
* Loop Electrical Characteristics are over recommended operating conditions unless otherwise stated.
† Typical figures are at 25°C and are for design aid only.
AC Electrical Characteristics *
†
Characteristics
Sym
Min
Typ
Max
Units
Test Conditions
1
2
2-wire Input Impedance
Zin
RL
600
Ω
Return Loss at 2-wire
(Zin = Ref = 600)
20
dB
200-3400 Hz
3
Longitudinal to Metallic
Balance
58
58
53
dB
200Hz
1000Hz
3.4kHz
4
5
6
Transhybrid Loss
THL
20
dB
dΒ
dB
200-3400Hz
1024Hz
Gain (voltage) 2 wire to Tx
-0.25
-2.25
0
0.25
Gain (Voltage)
Rx to 2 wire
-2
-1.75
Spec Freq
7
8
9
Input impedance at Rx
Output impedance at Tx
10
kΩ
5
Ω
Signal Overload Level
at 2-wire output
at Tx
% THD < 5%
Ref 600Ω @ 20mA
4.0
0.95
dBm
Vrms
10 Total Harmonic Distortion
THD
NC
at 2-wire
at Tx
1.0
1.0
%
%
Input 0.5V, 1kHz @ Rx
Input 0.5V, 1kHz @ Tip-Ring
11 Idle Channel Noise
at 2-Wire
13
13
dBrnc
dBrnc
at Tx
12 Power Supply Rejection Ratio PSRR
Ripple 0.1V, 1kHz
at 2-wire and Tx
VDD
VEE
30
30
dB
dB
* AC Electrical Characteristics are over recommended operating conditions unless otherwise stated.
† Typical figures are at 25°C and are for design aid only.
2-265
MH88634K
Preliminary Information
2.10 + 0.040
(53.3 + 1.0)
0.080 Max
(2.0 Max)
Side View
0.56 Max
(14.2 Max)
0.010 + 0.002
(0.25 + 0.05)
0.27 Max
(6.9 Max)
*
Notes:
1) Not to scale
2) Dimensions in inches).
0.05 + 0.01
(1.3 + 0.5)
0.18 + 0.02
(4.6 + 0.5)
*
*
*
3) (Dimensions in millimetres).
*Dimensions to centre of pin &
tolerance non accumulative.
0.05 + 0.02
(1.225 + 0.05)
0.100 + 0.010
(2.54 + 0.26)
0.020 + 0.005
(0.51 + 0.13)
Figure 3 - Mechanical Data
MH88634K
Tip
TIP
Protection
TX
Audio Out
Audio In
Circuit
RING
Ring
RX
LRD
K1
VRLY
LRC
XLA
RV
FL
Ring Detect
Loop Relay Control
Forward Loop
RL
SO
Reverse Loop
Service Loop
K1
XLB
NOTES:
XLC
XLD
VDD
1) See Figure 5 for
Protection Circuit.
2) K1 Electro Mechanical
2 form A.
K1
AGND VEE
-5V
+5V
Figure 4 - Typical LS-GS Application Circuit
2-266
Preliminary Information
MH88634K
Protection Circuit
MH88634K
RV1
TIP
TIP
R1
F1
RING
RV3
RING
RV2
F2
R2
AGND
NOTES
1) F1, F2 are 1 AMP 250 VAC Slow-blow fuse
e.g. Littlefuse 230 2AG
2) R1, 2 2.4 Ohm, 5% 1/2W, 100V Flame Rated
resistor e.g., Allen Bradley EB24G5-L05
3) RV1, 2, 3 250 VAC 351 Metal Oxide Varistor
e.g. OHIZUMI, 025ONC 12D
Figure 5 - External Application Circuit
2-267
MH88634K
Preliminary Information
Notes:
2-268
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