CS61310-IP Cirrus Logic, Inc., CS61310-IP Datasheet - Page 8

• Manufacturer Part Number: CS61310-IP
• Description: T1 line interface unit
• Manufacturer: Cirrus Logic, Inc.

2 THEORY OF OPERATION
The CS61310 Line Interface Unit is a fully inte-
grated transceiver for T1 long haul applications.
The transmitter outputs all pulse shapes for T1 ap-
plications.
2.1
The CS61310 can be operated as a stand-alone de-
vice with its interface in hardware mode (MODE
pin is low), or it can be operated by a microcontrol-
ler over a serial interface in host mode (MODE pin
is high). Host mode enables the use of additional
functionality, as described in the Serial Interface
section.
2.2
The CS61310 requires a reference clock for the re-
ceiver and the jitter attenuator. A 1.544 MHz exter-
nal clock can be input to MCLK, or a 4x crystal can
be connected to the on-chip oscillator. This fre-
quency reference should be within +32 ppm of the
nominal operating frequency. Jitter and wander on
the reference clock will degrade jitter attenuation
and receiver jitter tolerance. If MCLK is provided,
the crystal oscillator is ignored.
2.3
The transmitter accepts digital T1 input data and
drives appropriately shaped AMI (Alternate Mark
Inversion) pulses onto a transmission line through
a transformer. The transmit data (TPOS & TNEG
or TDATA) is sampled on the falling edge of the
input clock, TCLK.
The pulse shapes comply with FCC Part 68 Option
A (0 dB), Option B (-7.5 dB), Option C (-15 dB) or
(-22.5 dB) (see Table 1). Pulse shaping and signal
level are controlled by LBO1 and LBO2 pins in
hardware mode, or the LBO1 and LBO2 bits
(CR1.3 and CR1.4) in host mode.
Custom transmit pulse shapes may be implemented
by writing pulse shape coefficients to the registers.
8
Interface Modes
Master Clocks
Transmitter
Custom pulses may be used to correct for pulse
shape degradation or distortion caused by improper
termination, suboptimal interconnect wiring, or
loading from external components such as high
voltage protection devices.
For DS-1 applications, the arrangement in Table 1
meets ANSI T1.102 pulse shape requirements. A
typical output pulse is shown in Figure 6. These
pulse settings can also be used to meet ITU-T pulse
shape requirements for 1.544 MHz operation.
-0.5
1.0
0.5
0
0
Table 1. Pulse Shape Selection and Transformer
NORMALIZED
AMPLITUDE
Figure 6. Typical Pulse Shape for DS-1
LB02
0
0
1
1
250
PULSE SHAPE
LB01
OUTPUT
TIME (nanoseconds)
Requirements
0
1
0
1
500
Output Pulse
-22.5 dB
-7.5 dB
-15 dB
0 dB
SPECIFICATION
ANSI TI.102
750
CS61310
DS440PP2
1000