STANDARD PRODUCT
PM4351 COMET
DATA SHEET
PMC-1970624
ISSUE 10
COMBINED E1/T1 TRANSCEIVER
Input Transmit Data
Bit Settings
OCLKSEL1=0
OCLKSEL0=1
PLLREF1=1
PLLREF0=1
LINELB=0
Effect on Output Transmit Data
Synchronous to BTCLK output.
Transmit Backplane Configuration
register CMODE =0.
No jitter attenuation. TCLKO is equal to TCLKI (useful
for higher rate MUX applications). The BTCLK output
referenced to TCLKI. TX-ELST bypassed.
TXELSTBYP=1
OCLKSEL1=0
OCLKSEL0=1
PLLREF1=1
PLLREF0=1
LINELB=0
Synchronous to BTCLK input.
Transmit Backplane Configuration
register CMODE =1.
No jitter attenuation. TCLKO is equal to TCLKI (useful
for higher rate MUX applications). TX-ELST allows
BTCLK to be plesiochronous.
TXELSTBYP=0
OCLKSEL1=0
OCLKSEL0=0
PLLREF1=X
PLLREF0=0
LINELB=1
Transmit data ignored. Receive data
is looped back.
Line loopback with jitter attenuation.
TXELSTBYP=X
Upon reset of the COMET, these bits are cleared to zero, selecting jitter
attenuation with TCLKO referenced to the backplane transmit clock, BTCLK.
Figure 12 illustrates the various bit setting options, with the reset condition
highlighted. When TUNI is logic 0, PLLREF[1:0] must be configured such that
the internal 24x clock references the Transmit line clock.
PROPRIETARY AND CONFIDENTIAL
93
PMC [ PMC-SIERRA, INC ]
