MITEL MH88500IN


MH88500IN
Hybrid Subscriber Line Interface Circuit (SLIC)
Preliminary Information
ISSUE 1
Features
April 1995
Ordering Information
•
Differential to single ended conversion
•
No transformers required
•
Minimum installation space
•
Off-Hook detection and LED indicator drive
•
Relay drive output
•
Battery and ringing feed to line
•
Logic interface: MUTE, OFHK, RC
•
Mute of incoming audio
•
Dial pulse detection
•
Voltage surge protection
Line Interface for:
PABX
•
Intercoms
•
Key Systems
20 Pin SIL Package
0°C to 70°C
Description
The Mitel MH88500IN 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 MH88500IN 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 in a 20-pin ‘single-inline’ package allowing optimum circuit board packing
density.
Applications
•
MH88500IN
VA1
VA2
VC1
VB
GND
TIP
RING
RING
FEED
Loop Feed/
Ring Feed
JUNCTOR
Speech Circuit
VA2
VB
MUTE
CD
OFHK
RD
RC
RGND
Loop Detection
Relay Drive
Circuit
LED
THRESH ADJ
VC2
Figure 1 - Functional Block Diagram
2-43
MH88500IN
Preliminary Information
TIP
VA1
RING
RING FEED
IC
VC1
GND
VB
LED
OFHK
THRESH ADJ
VA2
GND
VC2
MUTE
JUNCTOR
RD
RGND
RC
CD
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
1
TIP
Tip Lead. Connects to the “Tip” lead (A-wire) of the telephone line.
2
VA1
Positive Line Feed Supply Voltage. Normally connected to VA2.
3
RING
4
RING FEED
5
IC
6
VC1
7
GND
8
VB
9
LED
10
OFHK
11
THRESH ADJ
12
VA2
13
GND
14
VC2
15
MUTE
16
JUNCTOR
17
RD
18
RGND
Ground for Relay Drive Circuit.
19
RC
Ring Control Input. Active high.
20
CD
Clamping Diode. Normally connected to relay positive voltage.
2-44
Description
Ring Lead. Connects to the “Ring” lead (B-wire) of the telephone line.
Negative Line Feed Voltage and Ringing Input. Normally connected to Ring Relay.
Internal Connection. Leave open circuit. Use for testing only.
Sense Input. Normally connected to negative line feed voltage supply.
Analog ground (0V). Internally connected to pin 13.
Negative Analog Supply Voltage.
LED Drive Output. Drives an LED directly. Off-Hook condition, logic low.
Logic Low Output. Indicates closed loop condition (Off-Hook and dial pulsing).
Allows adjustment of OFHK detection threshold.
Positive Power Supply Voltage. Normally connected to VA1.
Analog Ground (0V). Internally connected to pin 7.
Loop Detector Voltage Supply.Connected to negative line feed voltages supply.
Input mutes the incoming audio. Active low.
Receive/transmit audio speech path. (referenced to 0V GND)
Relay Drive Output. Open collector sinks current when RC high. Diode clamp
protected.
MH88500IN
Preliminary Information
Functional Description
Line Feed/Ring Feed Circuit
Speech Circuit
The speech circuit converts the bidirectional TIP and
RING line pair to a bidirectional single ended junctor
line. Figure 3 illustrates a typical connection between
two SLIC’s through two crosspoint switches. This
configuration gives optimum transhybrid loss as
seen from Figure 4 given that the output impedance
of the Junctor line is 604Ω.
The MUTE input mutes signals coming from TIP and
RING to the junctor line while allowing the signal
from the junctor to the tip-ring pair to be transmitted.
The line feed circuit provides loop current and the
ability to apply ringing onto TIP and RING. The
impedance from RING FEED to GND is 600Ω which
gives the loop current as:
IL = Voltage at RING FEED pin
Telephone Impedance + 600
Amps
The positive supply for the line feed circuit is VA1
through the loop current is determined from RING
FEED and GND.
Relay Drive Circuit
Loop Detection
The loop detection circuit determines whether a low
enough impedances is across TIP and RING to be
recognized as an off-hook condition.
(Threshold impedance = 5.4kΩ with no adjustment)
This threshold level can be adjusted by the use of
external resistors as shown in Figure 6. OFHK has
low output drive capability so it may drive CMOS
operating with different power supplies.
The relay drive circuit switches ringing onto RING
FEED (Fig.7). The diode is present to suppress
voltage transients during relay switches caused by
the inductive coils of the relay. Ringing voltage
includes AC ringing (90V typically) an dDC line feed
voltage (-24V typically).
MH88500IN
75Ω
1
TIP
16
TIP
JUNC
RING
3
CROSSPOINT
SWITCH
RING
MH88500IN
1
TIP
75Ω
TIP
16
JUNC
RING
3
RING
CROSSPOINT
SWITCH
Figure 3 - SLIC Crosspoint Switch Connection
2-45
MH88500IN
Preliminary Information
Absolute Maximum Ratings†
Parameter
1
Symbol
Voltage Supplies - VRef to GND
Min
Max
Units
VA1, VA2
V
VB
-18
VC1, VC2
-35
2
Clamp Diode Breakdown Voltage-VRef to RGND
VCD
3
Operating Temperature
TAMB
4
Storage Temperature
TSTG
5
Power Dissipation
+18
V
V
+15
V
0
+70
°C
-40
+100
°C
1.2
Watt
PD
† Exceeding these values may cause permanent damage. Functional operation under these conditions is not implied.
AC Electrical Characteristics†
Voltages are with respect to ground (VSS), TA = 25°C, unless otherwise stated.
Test conditions unless noted, VA1=VA2=+7V, VB=8V, VC2=-24V(+5%).
Characteristics
Sym
Min
Typ‡
Max
Units
Test Conditions
1
Junctor to differential output (tipring) gain.
AJL
0.8
1.0
0
1.2
V/V
dB
1kHz, 400mVRMS
source on pin 16.
Note 2
2
Differential Input (tip-ring) to
junctor gain
ALJ
0.8
1.0
0
1.2
V/V
dB
1kHz, 1VRMS
Source on pins 1&3.
Note 1,2
3
On/Off Hook Detection
Threshold
RThresh
IThresh
4.0
3.6
5.4
4.0
6.0
5.3
kΩ
mA
Note 1
Note 1
Loop Resist
Loop Current
4
Trans Hybrid Loss
55
dB
Notes 1,2. See
Figure 2
5
Passband Linearity
+1
dB
Notes 1,2
6
Power Supply Rejection Ratio
(VC to Junctor)
PSRR
40
dB
Notes 1,2
7
Common Mode Rejection Ratio
(Tip and Ring to Junctor)
CMRR
40
dB
Notes 1,2
8
Low Frequency Cutoff (3dB)
Junctor to Line
Line to Junctor
FLLJ
FLJL
53
20
Hz
Hz
Notes 1,2
Notes 1,2
High Frequency Cutoff (3dB)
Line to Junctor
Junctor to Line
FHLJ
FHJL
800
500
kHz
kHz
Notes 1,2
Notes 1,2
65
dB
Note 1
ZI
300
Ω
ZOJ
604
Ω
9
10
Longitudinal Balance
11
Tip (or Ring) to ground AC input
impedance
12
Junctor output impedance
† Exceeding these values may cause permanent damage. Functional operation under these conditions is not implied.
‡ Typical figures are at 25°C with nominal +5V supplies and are for design aid only: not guaranteed and not subject to production testing.
Note 1: 754Ω connected between JUNCTOR (pin 16) and 0V.
Note 2: 604Ω connected between TIP (pin 1) and RING (pin 3).
2-46
MH88500IN
Preliminary Information
.
DC Electrical Characteristics
Characteristics
Operating Supply Voltages
1
2
S
U
P
P
L
Y
Sym
Min
Typ‡
VA1,VA2
VB
VC1,VA2
-13
-30
-24
Max
Units
+13
V
V
V
Test Conditions
-20
Operating Supply Currents
IA1
7
8
6
.2
.1
IA2
IB
IC1
IC2
mA
mA
mA
mA
mA
High Level Input Voltage
MUTE
RC
VIH
Low Level Input Voltage
MUTE
RC
.8
1
V
VIL
High Level Input Current
MUTE
RC
IIH
IIH
-28
700
µA
µA
Low Level Input Current
MUTE
RC
IIL
IIL
100
1
µA
µA
ILED
IRD
2
65
6
100
mA
mA
VOFHK,-6V
CD=RC=5V,RGD=0V
VRRD<1.5V
Diode Clamp Current
IRLY
65
100
mA
RC=RGND=0V,
CD=5V VRRD <1.5V
High Level Output Voltage
VOH
6
V
LED Unconnected
Low Level Output Voltage
OFHK
VOL
-6.5
V
LED Unconnected
11
High Level Output Current
IOH
10
µA
12
Low Level Output Current
IOL
10
µΑ
3
4
5
I
N
P
U
T
S
6
9
10
VIL
V
V
4.2
3
Sink Current
7
8
VIH
O
U
T
P
U
T
S
LED
RD
‡ Typical figures are at 25°C with nominal+ 5V supplies and are for design aid only: not guaranteed and not subject to production testing.
TRANSHYBRID
LOSS
(dB)
10
20
30
40
50
60
550
600 650
700 750
800
850
900
950
LOAD IMPEDANCE ON JUNCTOR (Ω)
Figure 4 - Return Loss VS Junctor Load Impedance
2-47
MH88500IN
Preliminary Information
VO
754Ω
5
1
VTR
604Ω
54Ω
1
200Ω
16
VTR
5
604Ω 10µF
MH88500IN
MH88500IN
VS
10H
VX
3
16
3
CAN BE MEASURED THAT
TRANSHYBRID LOSS = - 20LOG (VO)
(b)
2VS
VTP=2VX=2VTR
(a)
Figure 5 - Transhybrid Loss Test Circuit
R and RTHRESH (kΩ )
R and RTHRESH (kΩ)
(a)
(a)
GND
VC2
R
MH88500IN
R
MH88500IN
11
11
THRESH
ADJ
THRESH
ADJ
(48 x RTHRESH) -28.8
R=
5.4 - RTHRESH
R
(kΩ)
R=
(912 x RTHRESH) +604
RTHRESH - 5.4
R
(kΩ)
2000
120
100
80
1000
60
40
20
1
2
3
4
5
6
10
RTHRESH (kΩ)
(a)
Figure 6 - Off-Hook Threshold Adjust
2-48
20
30
40
RTHRESH (kΩ)
(b)
MH88500IN
Preliminary Information
VA1
TIP
LINE FEED/
RING FEED
RING
-24VDC
-24VDC
RING FEED
+90VAC
+V
MH88500IN
CLAMP DIODE
CD
RELAY COIL
RD
RELAY
DRIVE
CIRCUIT
RC
RGND
Figure 7 - Relay Drive Circuit
2-49
MH88500IN
Preliminary Information
+7v +5V
CONTROL
-24VDC
90VAC
-24VDC
00
01
02
03
04
05
06
07
A0
A1
A2
LOGIC
2
12
1
TIP
MH88500IN
19
3
RING
16
ADDRESS
OUT
9 20 17 4
15
10
MD74SC137
1 OF 8
DECODER
+5V
8
6
14
7
-8V
-24V
0V
+5V
+7V +5V
5 MORE
SLICS
-24VDC
90VAC
00
-24VDC
01
A0
A1
A2
02
12 9 20 17 4
TIP
2
15
03
04
05
06
07
MH88500IN
19
10
8
16
-8V
MD74SC137
1 OF 8
DECODER
+7V
6
+5V
3
RING
14
-24V
1
7
0V
+5V
-24VDC
90VAC
5 MORE
SLICS
A0-A2/D0-D3
J0
MT8812
J1
Crosspoint J
2
Switch
J3
-L7
L0
A0
A1
A2
CMOS
4512
8-INPUT
MUX
SELECT
OUTPUT
D0
D1
D2
|
|
D7
-24VDC
2
15
12 9 20 17 4
19
MH88500IN
10
RING
16
8
-8V
Figure 8 - PABX Typical Application
2-50
1
TIP
6
14
-24V
7
0V
3
MH88500IN
Preliminary Information
0.080 Max
(2.0 Max)
Side View
2.00 + 0.020
(50.8 + 0.5)
0.52+0.02
(13.2+0.5)
1 2 3 4
19 20
0.010 + 0.002
(0.25 + 0.05)
0.12 Max
(3.1 Max)
Notes:
1) Not to scale
2) Dimensions in inches).
3) (Dimensions in millimetres).
*Dimensions to centre of pin &
tolerance non accumulative.
*
0.05 + 0.01
(1.3 + 0.5)
*
0.05 + 0.02
(1.3 + 0.05)
*
0.020 + 0.05
(0.51 + 0.13)
*
0.18 + 0.02
(4.6 + 0.5)
0.100 + 0.10
(2.54 + 0.13)
Figure 9 -Mechanical Data
2-51
MH88500IN
Notes:
2-52
Preliminary Information