LXT310
—
T1 CSU/ISDN PRI Transceiver
16
Datasheet
3.1.1
Host Mode Applications
Figure 7
shows a typical T1 CSU application with the LXT310 operating in the Host mode (MODE
pin tied high). A T1/ESF Framer provides the digital interface with the host controller. Both
devices are controlled through the serial interface. In the Host mode, the LOS alarm is reported via
the serial port so the LOS pin is allowed to float.
An LXP600A Clock Adapter (CLAD) provides the 2.048 MHz system backplane clock, locked to
the recovered 1.544 MHz clock signal. The 6.176 MHz crystal across XTALIN and XTALOUT
enables the JAL that is switched to the transmit side by the Low on JASEL. Refer to
Table 5
for
approved crystals and transformers. The power supply inputs are tied to a common bus with
appropriate decoupling capacitors (68 μF and 0.1 μF) installed on each side.
The twisted-pair interfaces are relatively simple. A 100
resistor across the input of a 1:1
transformer is used on the receive side, and a pair of 12.5
resistors are installed in line with the
1:2 output transformer.
Tx Transformer
(1: 2)
Bell Fuse
0553-5006-IC
FEE Fil-Mag
66Z1308
Midcom
671-5832
Pulse Engineering
65351, 65771
Schott Corp
67127370 and 67130850
HALO
TD61-1205G and TD67-1205G (combo Tx/Rx)
Rx Transformer
(1: 1)
FEE Fil-Mag
FE 8006-155
Midcom
671-5792
Pulse Engineering
64936 and 65778
Schott Corp
67130840 and 67109510
HALO
TD61-1205G and TD67-1205G (combo Tx/Rx)
Table 5. Approved Crystals and Transformers
Component
Manufacturer
Part Numbers
1. The customer should always verify the specifications of the quartz crystal against Intel
’
s recommended specification
point-
by-point
to make certain that the crystal suits the desired application.
Table 6. LXT310 Crystal Specifications (External)
Parameter
Specification
Frequency
6.176 MHz
Frequency stability
± 20 ppm @ 25
°
C
± 25 ppm from -40
°
C to 85
°
C
(Ref 25
°
C reading)
Pullability
CL = 11 pF to 18.7 pF, +
F = 175 to 195 ppm
CL = 18.7 pF to 34 pF, -
F = 175 to 195 ppm
Effective series resistance
40
Maximum
Crystal cut
AT
Resonance
Parallel