CN8380 Datasheet, PDF (56/91 Pages) Conexant Systems, Inc – integrated quad line interface unit unit for both 1.544 Mbps (T1) and 2.048 Mbps (E1) applications

3.0 Registers
3.2 Global Control and Status Registers
CN8380
Quad T1/E1 Line Interface
CMUX[2:0]
CLAD Multiplexer Select—Selects the CLAD reference clock source input to the CLAD
phase detector if FREE = 0 [CLAD_CR; addr 02]. The source can be the receive recovered
clock output (RCKO) from any of the four channels or the CLAD input pin.
000 = CLADI pin
001 = RCKO[1] from channel #1
010 = RCKO[2] from channel #2
011 = RCKO[3] from channel #3
100 = RCKO[4] from channel #4
02—CLAD Configuration (CLAD_CR)
7
FREE
6
RSCALE[2]
5
RSCALE[1]
4
RSCALE[0]
3
LFGAIN[3]
2
LFGAIN[2]
1
LFGAIN[1]
R/W
0
LFGAIN[0]
FREE
RSCALE[2:0]
LFGAIN[3:0]
Free-Run CLAD—Disables the CLAD phase detector in the CLAD, which forces the
numerically controlled oscillator (NCO) to free-run based on the 10 MHz REFCKI input clock
accuracy.
0 = normal (closed loop) CLAD operation
1 = free run (open loop) NCO operation
CLAD Reference Scale Factor—Divides CLAD reference signal by 2 ^[RSCALE] to form
CLADR input to the phase detector. Applicable only if FREE is 0. Allows the system to supply
CLADI frequency, up to a maximum of 128 times the desired CLADR reference frequency.
RSCALE Scale Factor CLADR Reference
000
1
CLADR = CLADI
001
2
CLADR = CLADI/2
010
4
CLADR = CLADI/4
011
8
CLADR = CLADI/8
100
16
CLADR = CLADI/16
101
32
CLADR = CLADI/32
110
64
CLADR = CLADI/64
111
128
CLADR = CLADI/128
Loop Filter Gain— Selects the NCO loop filter's proportional phase error gain. Lower gain
values reduce phase response time, and higher gain values increase phase response time. Note
that loop instability or acquisition failures may result from incorrectly programmed LFGAIN
values.
LFGAIN Proportional Gain
0000
|
1111
1/2⁰
|
1/2¹⁵
3-4
Conexant
N8380DSA
Advance Information
4/21/99