CS61884-IQZ Cirrus Logic Inc, CS61884-IQZ Datasheet - Page 24

• Manufacturer Part Number: CS61884-IQZ
• Description: IC,PCM TRANSCEIVER,OCTAL,CEPT PCM-30/E-1,QFP,144PIN,PLASTIC
• Manufacturer: Cirrus Logic Inc

Specifications of CS61884-IQZ

• Rohs Compliant: YES

9. TRANSMITTER
The CS61884 contains eight identical transmitters
that each use a low power matched impedance driv-
er to eliminate the need for external load matching
resistors, while providing superior return loss. As a
result, the TTIP/TRING outputs can be connected
directly to the transformer allowing one hardware
circuit for 100 Ω (T1/J1), 120 Ω (E1), and 75 Ω
(E1) applications.
Digital transmit data is input into the CS61884
through the TPOS/TNEG input pins. These pins ac-
cept data in one of three formats: unipolar, bipolar,
or RZ. In either unipolar or bipolar mode, the
CS61884 internally generates a pulse shape com-
pliant to the ANSI T1.102 mask for T1/J1 or the
G.703 mask for E1 (Refer to
Figure
data can be selected in hardware mode or in host
mode.
In hardware mode, the pulse shape is selected for
all channels via the LEN[2:0] pins (Refer to
Table 5 on page
all eight transmitters to one of the prestored line
lengths. The CBLSEL pin in combination with the
LEN[2:0] pins set the line impedance for all eight
channels. The CBLSEL pin also selects between
E1 120Ω or E1 75Ω modes, when the LEN pins are
configured for E1 operation mode.
In host mode, the pulse shape for each channel can
be set independently, during NRZ operation mode,
for proper clock recovery and jitter attenuation. In
RZ Mode each channel can be set to either T1/J1 or
E1, when there is no Mclk present (Refer to
Mode
To select the standard pulse shapes, the channels
are selected individually using the
Channel ID Register (10h)
page 38), then the LEN[3:0] bits in the
Length Data Register (11h)
page 39) are set for the desired line length for that
channel. The LEN bits select the line type and im-
24
(See Section 9.3 on page 25).
7). The pulse shaping applied to the transmit
25). This sets the pulse shape for
(See Section 14.17 on
(See Section 14.18 on
Figure 6
Line Length
Line
and
RZ
pedance for both the receiver and the transmitter of
the addressed channel.
NOTE: In host mode the CBLSEL pin is not used.
P e rce n t o f
n o m ina l pe a k
vo lta g e
-0.5
1.0
0.5
0
0
12 0
11 0
100
-1 0
-2 0
90
80
50
10
0
Normalized
Amplitude
Figure 6. Pulse Mask at T1/J1 Interface
Figure 7. Pulse Mask at E1 Interface
250
Output Pulse
Shape
TIME (nanoseconds)
2 6 9 n s
2 4 4 n s
1 9 4 n s
2 1 9 n s
4 8 8 n s
500
750
AT&T CB 119
Specifications
ANSI T1.102,
CS61884
N o m in a l P u ls e
1000
DS485F1