LXT350 — T1/E1 Short Haul Transceiver with Crystal-less Jitter Attenuation
Table 6. Diagnostic Mode Availability
Availability1
Host Mode
Maskable2
Diagnostic Mode
Hardware
Host
Bipolar Violation Detection (BPV)
Yes
Yes
No
Yes
Yes
Yes
Yes
No
No
No
No
Logic Error Detection, QRSS (QPD)
HDB3 Code Violation Detection (CODEV)
HDB3 Zero violation Detection (ZEROV)
No
Alarm Condition Monitoring
Receive Loss of Signal (LOS) Monitoring
Yes
No
No
No
No
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Receive Alarm Indication Signal (AIS) Monitoring
Transmit Driver Failure Monitoring—Open (DFMO)
Elastic Store Overflow and Underflow Monitoring
Built-In Self Test (BIST)
1. In Hardware mode, a combination of pin settings selects the Diagnostics Modes. In Host mode, writing appropriate bits in the
Control Registers selects the Diagnostic Modes.
2. Host mode allows interrupt masking by writing a “1” to the corresponding bit in the Interrupt Clear Register.
2.7.1
Loopback Modes
2.7.1.1
Local Loopback (LLOOP)
See Figure 5 and Figure 6. LLOOP inhibits the receiver circuits. The transmit clock and data inputs
(TCLK and TPOS/TNEG or TDATA) loop back through the jitter attenuator (if enabled) and
appear at RCLK and RPOS/RNEG or RDATA. Note that during LLOOP, the JASEL input is
strictly an enable/disable control, i.e. it does not affect the placement of the JA. If the JA is enabled,
it is active in the loopback circuit. If the JA is bypassed, it is not active in the loopback circuit.
The transmitter circuits are unaffected by LLOOP and the LXT350 continues to transmit the
TPOS/TNEG or TDATA inputs (or a stream of 1’s if TAOS is asserted). When used in this mode,
the transceiver can function as a stand-alone jitter attenuator.
In Hardware mode, Local loopback (LLOOP) is selected by setting LLOOP High; in Host mode,
by setting bit CR2.ELLOOP = 1.
20
Datasheet
ETC [ ETC ]
