PDLXT310NE.D4 Intel, PDLXT310NE.D4 Datasheet - Page 14

• Manufacturer Part Number: PDLXT310NE.D4
• Manufacturer: Intel

Specifications of PDLXT310NE.D4

• Number Of Line Interfaces: 1
• Lead Free Status / Rohs Status: Not Compliant

LXT310 — T1 CSU/ISDN PRI Transceiver
2.5.3
2.5.3.1
2.5.3.2
2.5.3.3
2.5.3.4
14
Diagnostic Mode Operation
Transmit All Ones
In Transmit All Ones (TAOS) mode, the TPOS and TNEG inputs to the transceiver are ignored and
the transceiver transmits a continuous stream of ones at the TCLK frequency. If TCLK is not
provided, TAOS is locked to the MCLK. This can be used as the Blue Alarm Indicator (AIS). In
Host mode, TAOS is commanded by writing a one to bit D7 of the input data byte. In Hardware
mode, TAOS is commanded by setting pin 28 High. TAOS can be commanded simultaneously
with Local Loopback, but is inhibited during Remote Loopback.
Local Loopback
Local Loopback (LLOOP) is designed to exercise the maximum number of functional blocks.
During LLOOP operation, the RTIP/RRING inputs from the line are disconnected. Instead, the
transmit outputs are routed back into the receive inputs. This tests the encoders/decoders, jitter
attenuator, transmitter, receiver and timing recovery sections. In Host mode, Local Loopback is
commanded by writing a one to bit D6 of the input data byte. In Hardware mode, Local Loopback
is commanded by setting pin 27 High. If TAOS and LLOOP are both set, the All Ones pattern is
transmitted onto the line while the TPOS/TNEG input data is looped back to the RPOS/RNEG
outputs.
Remote Loopback
In Remote Loopback (RLOOP) mode, the transmit data and clock inputs (TCLK and TPOS/TNEG
or TDATA) are ignored, and the in-line encoders and decoders are bypassed. The RPOS/RNEG or
RDATA outputs are looped back through the transmit circuits and output on TTIP and TRING at
the RCLK frequency. Receiver circuits are unaffected by the RLOOP command and continue to
output the RCLK and RPOS/RNEG or RDATA signals received from the twisted-pair line. In Host
mode, Remote Loopback is commanded by writing a one to bit D5 of the input data byte. In
Hardware mode, Remote Loopback is commanded by setting pin 26 High.
Network Loopback
Network Loopback can be commanded from the network when the Network Loopback detect
function is enabled. In Host mode, Network Loopback (NLOOP) detection is enabled by
simultaneously writing ones to RLOOP, LLOOP and TAOS, then writing zeros in the next cycle.
In Hardware mode, Network Loopback detection is enabled by holding RLOOP, LLOOP and
TAOS High simultaneously for 200 ns then bringing them Low, or by tying RCLK to RLOOP.
NLOOP detection may be disabled by resetting the chip.
When NLOOP detection is enabled, the receiver monitors the input data stream for the NLOOP
data patterns (00001 = enable, 001 = disable). When an NLOOP enable data pattern is repeated for
a minimum of five seconds (with 10-3 BER), the device begins remote loopback operation. The
LXT310 responds to both framed and unframed NLOOP patterns. Once remote network loopback
detection is enabled at the chip and activated by the correct data pattern, it is identical to remote
loopback initiated at the chip. NLOOP is reset by receiving the disable pattern for 5 seconds, or by
activation of RLOOP. NLOOP is temporarily interrupted by LLOOP, but the NLOOP state is not
reset.
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