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QuadFALC
TM
PEF 22554 E
Functional Description E1/T1/J1
Data Sheet
120
Rev. 1.2, 2006-01-26
3.7.1
Transmit Line Interface
The transmit line interface includes two integrated serial resistors R
modes are possible:
For non-generic applications the extermal serial resistance R
SER is dependent on the operation mode
(E1/T1/J1) as shown in Table 26. The additional register bit PC6.TSRE is not used, R
TX is always 2 .
For generic E1/T1/J1 applications with optimized return loss the transmit output resistance R
TX is configured
by the register bit PC6.TSRE: The operation mode (E1/T1/J1) is selected by software without the need for
external hardware changes: Here the external resistor R
In E1 mode the value of R
SER in Table 26 is valid for both characteristic line impedances Z0 = 120 and Z0 = 75 . Figure 34
Transmit Line Interface
Note that shorts between XL1 and XL2 cannot be detected, because the short circuit current is lower than 120 mA.
This way a short between XL1 and XL2 will not harm the device.
Note that because of the integrated serial resistors R
TX in the transmit line interface the external termination
resistors R
SER must be changed against that of the Version 3.1.
Similar to the receive line interface three different data types are supported:
Ternary Signal: Single-rail data is converted into a ternary signal which is output on pins XL1 and XL2.
Selection between B8ZS or simple AMI coding with zero code suppression (B7 stuffing) is provided. B7 stuffing
can be disabled on a per time slot basis (Clear Channel capability). Selected by FMR0.XC(1:0) and
LIM1.DRS = 0.
Dual-rail data PCM(+), PCM(-) at multifunction ports XDOP and XDON with 50% or 100% duty cycle and with
programmable polarity. Line coding is done in the same way as in ternary interface mode. Selected by
FMR0.XC1 = 1 and LIM1.DRS = 1.
Unipolar data on port XOID is transmitted in NRZ (non return to zero) with 100% duty cycle or in CMI code with
or without (SIC3.CMI) preprocessed by B8ZS coding to a fiber-optical interface. Data is clocked on the rising
edge of the transmit clock XCLK (1544 kHz). Selection is done by FMR0.XC1 = 0 and LIM1.DRS = 1.
An overview of the line coding is given in Table 14.
Table 26
Recommended Transmitter Configuration Values
R
SER [Ohm], accuracy ± 1 % Application Mode
PC6.TSRE
R
TX [Ohm],
Operation Mode
0
1)
1) The values in this column refers to an ideal transformer without any parasitics. Any transformer resistance or other parasitic
resistances have to be taken into account when calculating the final value of the output serial resistors.
Generic
1
7.5
E1
00
2.0
T1/J1
5.5
Non generic
0
2.0
E1
00
2.0
T1/J1
internally
externally
R
TX
XL1
XL2
Z
0
QuadFALC_TX-interface
R
SER
R
SER
R
TX