XE1030 Cermetek Microelectronics, XE1030 Datasheet - Page 7

• Manufacturer Part Number: XE1030
• Manufacturer: Cermetek Microelectronics

Specifications of XE1030

• Lead Free Status / Rohs Status: Supplier Unconfirmed

XE1030 Applications Notes
2/4 Wire Conversion:
Full Duplex communications over a two-wire telephone line requires that transmit and receive signal share the available bandwidth.
The two-to-four wire convertor separates these signals at the host interface. Most modem analog front end chips incorporate an
internal 2/4 wire convertor making it unnecessary to provide one in the DAA.
If you are using the XE1030 for an application other than a modem, or your modem analog front end does not provide the 2/4 wire
convertor, you will need to provide a discrete 2/4 wire convertor. The schematic below illustrates a simple 2/4 wire convertor circuit
2/4 Wire Convertor
The pelevel of separation provided by the 2/4wire convertor is measured by its Transhybrid Loss. The Transhybrid Loss shows
how much he 2/4 wire convertor attenuates the transmit signal on the received data line. The circuit above provides a typical
Transhybrid Loss of 20 dB.
The Transhybrid Loss will vary with the quality of the impedance match to the telephone line. Even when the recommended value
for the impedance matching resistor, R6, is used variations from line to line alter the impedance match. The value of R3 can be
changed to improve the Transhybrid Loss.
The 2/4 wire convertor also amplifies the transmit and receive signals to compensate for the insertion loss of the DAA. This circuit
provides 6 dB gain of both the transmit and receive signals. The values of R1 and R2 set the transmit gain. The values of R4 and
R5 set the receive gain.
XECOM
R1=10k
3
2
7
+
_
R2=22k
TL082C
R4=40k
1
6
5
(7)
R5=11K
R6=10K
R3=20k
RT
T1
T2
DAA
XE1030