CS61305A Просмотр технического описания (PDF) - Cirrus Logic
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CS61305A Datasheet PDF : 44 Pages
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CS61305A
Percent of
nominal
peak
voltage
120
110
100
90
80
269 ns
244 ns
194 ns
50
10
Nominal Pulse
0
-10
-20
219 ns
488 ns
Figure 9. Mask of the Pulse at the 2048 kbps Interface
Transmit All Ones Select
0
a) Minimum Attenuation Limit
10
AT&T 62411
20
Requirements
30
40 b) Maximum
Attenuation
50
Limit
60
Measured Performance
1
10
100
1k
10 k
Frequency in Hz
Figure 10. Typical Jitter Attenuation Curve
Jitter Attenuator
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.
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
For coaxial cable, For shielded twisted
75Ω l o a d a nd pair, 120Ω load and
transformer specified transformer specified
in Application Section. in Application Section.
Nominal peak voltage of a mark (pulse)
2.37 V
3V
Peak voltage of a space (no pulse)
0 ±0.237 V
0 ±0.30 V
Nominal pulse width
244 ns
Ratio of the amplitudes of positive and negative
pulses at the center of the pulse interval
0.95 to 1.05*
Ratio of the widths of positive and negative
pulses at the nominal half amplitude
0.95 to 1.05*
* When configured with a 0.47 µF nonpolarized capacitor in series with the TX transformer
primary as shown in Figures A1, A2 and A3.
Table 4. CCITT G.703 Specifications
DS157PP3
11
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