MITEL MH89726, MH89728 Datasheet
MH89726/728
MT8972 Loop Extender Circuits
Advance In formation
Features
• Operates from single or dual power supply
• MH89726 extends transmission performance
for the MT8972 (DNIC) at 160kbit/s line rate
• MH89728 extends transmission performance
for the MT8972 (DNIC) at 80kbit/s line rate
• MH89726 and MH89728 are pin for pin
compatible with each other
• Compact SIL package
• Over 6km loop range on 24 AWG
Applications
• Digital subscriber lines
• Digital PABX line cards and telephone sets
• High speed, limited distance modem
• ISDN U - Interface
ISSUE 2 November 1990
Ordering Information
MH89726/728 10 Pin SIL Package
0°C to 70°C
Description
The MH89728 and MH89726 are thick film hybrid
devices which may be used to extend the operating
range of the MT8972 (DNIC). The hybrids combine
signal equalization and amplification for the receive
and transmit paths on each device.
The small size of these hybrids makes them suitable
for line card or terminal use with the MT8972. The
gain of the t ransmit signal ma y be adjusted th rough
the use of a n ex te rn al r e s ist or.
RX
TX
OUT
TX
GAIN
IN
Phase
Compensator
V
Bias
Pre-
Equalizer
Pre-
Canceller
Amplifier
RX
Amplifier
TEST V+V
TX
TX
OUT
RX
-
IN
RX
+
IN
-
Figure 1 - Functional Bloc k Diagram
9-127
MH89726/728 Advance Information
TXGAIN
TXOUT
RXIN +
RXIN -
V -
VBias
V +
TEST
RXOUT
TXIN
1
2
3
4
5
6
7
8
9
10
Figure 2 - Pin Conn ectio ns
Pin Description
Pin # Pin Name Description
1TX
2TX
3RX
4RX
GAIN
OUT
ININ+
5V-Negative power supply.
Transmit Gain. To be connected to Pin 2. An increase in gain can be achieved by
connecting an external resistor R
between Pin 1 and Pin 2. The resultant gain is
EXT
calculated using; A= (R/24) + 2.8, where A=Gain and R= R
Transmit Output. Connect to the termination network.
Negative Receive Signal. Connect to TX
OUT
, Pin 2.
Positive Receive Signal. Connected to line transformer.
EXT
(kΩ).
6V
Bias
Internal Bias Voltage. Connect to GND through 0.33 µF for single power supplies.
Connect to GND directly for split power supplies.
7V+Positive power supply.
8TESTTest. Used for production testing. Leave unconnected.
9RX
10 TX
OUT
IN
Receive Output. Connect to LIN (Pin 21) of MT8972.
Transmit Input. Connect to L
(Pin 1) of MT8972.
OUT
9-128
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