Datasheet

DS26303: 3.3V, T1/E1/J1, Short-Haul, Octal Line Interface Unit
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Figure 6-9. Digital Loopback
Line
Driver
HDB3/
B8ZS
Encoder
O ptional
Jitter
A ttenuator
Transm it
Digital
Transm it
Analog
TCLK
TPOS
TNEG
HDB3/
B8ZS
D ecoder
O ptional
Jitter
A ttenuator
Receive
Digital
Receive
Analog
RCLK
RPOS
RNEG
RTIP
RRING
TPOS
TNEG
6.8.3 Remote Loopback
The inputs at RTIPn and RRINGn are looped back to TTIPn and TRINGn. The inputs at TPOSn, and TNEGn are
ignored during a remote loopback. While the TCLKn pin is ignored in remote loopback mode for the data path, the
TCLKn pin must have an active signal applied in order to keep the transmitter operational. See the TCLKn pin
description for details. This loopback is conceptually shown in
Figure 6-10.
Figure 6-10. Remote Loopback
Line
Driver
HDB3/
B8ZS
Encoder
O ptional
Jitter
A ttenuator
Transm it
Digital
Transm it
Analog
TCLK
TPOS
TNEG
HDB3/
B8ZS
D ecoder
O ptional
Jitter
A ttenuator
Receive
Digital
Receive
Analog
RCLK
RPOS
RNEG
RTIP
RRING
TPOS
TNEG