CS61880-IQZ Cirrus Logic Inc, CS61880-IQZ Datasheet - Page 30

• Manufacturer Part Number: CS61880-IQZ
• Description: IC Octal E1 Line Interface Unit
• Manufacturer: Cirrus Logic Inc

12.3 Digital Loopback
Digital Loopback causes the TCLK, TPOS, and
TNEG (or TDATA) inputs to be looped back
through the jitter attenuator (if enabled) to the
RCLK, RPOS, and RNEG (or RDATA) outputs.
The receive line interface is ignored, but data at
TPOS and TNEG (or TDATA) continues to be
transmitted to the line interface at TTIP and
TRING (Refer to
Digital Loopback is only available during host
mode. It is selected using the appropriate bit in the
Digital Loopback Reset Register (0Ch)
tion 14.13 on page 36).
NOTE: TAOS can also be used during the Digital Loop-
30
RPOS
RNEG
TPOS
TNEG
RCLK
TCLK
RPOS
RNEG
MCLK
TAOS
TPOS
TNEG
RCLK
TCLK
back operation for the selected channel (Refer
to
Figure 10 on page
Figure 9 on page
31).
Figure 8. Analog Loopback with TAOS Block Diagram
Figure 7. Analog Loopback Block Diagram
31).
(See Sec-
12.4 Remote Loopback
In remote loopback, the RPOS/RNEG and RCLK
outputs are internally input to the transmit circuits
for output on TTIP/TRING. In this mode the
TCLK, TPOS and TNEG inputs are ignored. (Refer
to
mote Loopback is selected by driving the LOOP
pin for a certain channel low. In host mode, Remote
Loopback is selected for a given channel by writing
a one to the appropriate bit in the
back Register (02h)
page 35).
NOTE: In hardware mode, Remote Loopback over-
Clock Recovery &
Clock Recovery &
Data Recovery
Data Recovery
Pulse Shaper
Pulse Shaper
Figure 11 on page
Control &
Control &
Transmit
Transmit
rides TAOS for the selected channel. In host
mode, TAOS overrides Remote Loopback.
31)
.
(See Section 14.3 on
In hardware mode, Re-
Remote Loop-
CS61880
(All One's)
RRING
TRING
RTIP
RRING
TTIP
TRING
TTIP
RTIP
DS450PP3