CS61305A-IL1 Cirrus Logic, Inc., CS61305A-IL1 Datasheet - Page 11

• Manufacturer Part Number: CS61305A-IL1
• Description: T1/E1 line interface
• Manufacturer: Cirrus Logic, Inc.

Transmit All Ones Select
The transmitter provides for all ones insertion at
the frequency of ACLKI. Transmit all ones is se-
lected when TAOS goes high, and causes
continuous ones to be transmitted on the line
(TTIP and TRING). In this mode, the TPOS and
TNEG (or TDATA) inputs are ignored. A TAOS
request will be ignored if remote loopback is in
effect. ACLKI jitter will be attenuated. TAOS is
not available on the CS61305A when ACLKI is
grounded.
DS157PP3
Figure 9. Mask of the Pulse at the 2048 kbps Interface
120
110
100
-10
-20
90
80
50
10
0
Percent of
nominal
peak
voltage
Nominal peak voltage of a mark (pulse)
Peak voltage of a space (no pulse)
Nominal pulse width
Ratio of the amplitudes of positive and negative
pulses at the center of the pulse interval
Ratio of the widths of positive and negative
pulses at the nominal half amplitude
* When configured with a 0.47 F nonpolarized capacitor in series with the TX transformer
primary as shown in Figures A1, A2 and A3.
269 ns
244 ns
194 ns
219 ns
488 ns
Nominal Pulse
Table 4. CCITT G.703 Specifications
Fo r c o ax i al c a bl e,
75
transformer specified
in Application Section.
Jitter Attenuator
The jitter attenuator is designed to reduce wander
and jitter in the transmit clock signal. It consists
of a 192 bit FIFO, a crystal oscillator, a set of
load capacitors for the crystal, and control logic.
The jitter attenuator exceeds the jitter attenuation
requirements of Publications 43802 and REC.
G.742. A typical jitter attenuation curve is shown
in Figure 10.
The jitter attenuator works in the following man-
ner. Data on TPOS and TNEG (or TDATA) are
10
20
30
40
50
60
0 0.237 V
0
Figure 10. Typical Jitter Attenuation Curve
1
2.37 V
l o a d
b) Maximum
Attenuation
Limit
10
0.95 to 1.05*
0.95 to 1.05*
a nd
244 ns
a) Minimum Attenuation Limit
For shielded twisted
pair, 120
transformer specified
in Application Section.
100
Frequency in Hz
0 0.30 V
Requirements
AT&T 62411
Measured Performance
3 V
CS61305A
1 k
load and
10 k
11