LXT351 — T1/E1 Short Haul Transceiver with Crystal-less Jitter Attenuation
2.5.1.2
Analog Loopback
See Figure 6. Analog loopback (ALOOP) exercises the maximum number of functional blocks.
ALOOP operation disconnects the RTIP/RRING inputs from the line and routes the transmit
outputs back into the receive inputs. This tests the encoders/decoders, jitter attenuator, transmitter,
receiver and timing recovery sections. Writing a 1 to bit CR2.EALOOP enables the ALOOP mode.
Note that ALOOP will override all other loopback modes.
Figure 6. Analog Loopback
2.5.1.3
Remote Loopback
See Figure 7. In Remote loopback (RLOOP) mode, the device ignores the transmit data and clock
inputs (TCLK and TPOS/TNEG or TDATA), and bypasses the in-line encoders/decoders. The
RPOS/RNEG or RDATA outputs loop back through the transmit circuits to TTIP and TRING at the
RCLK frequency. The RLOOP command does not affect the receiver circuits which continue to
output the RCLK and RPOS/RNEG or RDATA signals received from the twisted-pair line.
RLOOP is selected by writing a 1 to bit CR2.ERLOOP.
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Datasheet
INTEL [ INTEL ]
