CN8380 Datasheet, PDF (48/91 Pages) Conexant Systems, Inc – integrated quad line interface unit unit for both 1.544 Mbps (T1) and 2.048 Mbps (E1) applications

2.0 Circuit Description
2.7 Clock Rate Adapter
2.7.1 Inputs
2.7.2 Outputs
CN8380
Quad T1/E1 Line Interface
In Hardware Mode, the CLAD input timing reference is normally taken from a
line rate (1,544 kHz—T1 or 2,048 kHz—E1) clock on the CLADI pin. The line
rate is determined globally for all channels by settings on the PTS(2:0) pins. The
CLAD can be set in free-run mode by removing the clock from CLADI (pull high
or low). If clock edges are not present on CLADI, an internal clock monitor
automatically switches the timing reference to use the 10 MHz, REFCKI
reference. When clock edges are sensed on CLADI, the reference is switched
back to CLADI.
In Host Mode, the CLAD input timing reference can be selected from six
sources. The source can be the received recovered clock (or jitter attenuated
clock) output (RCKO[n]) from any of the four channels, the CLADI input pin, or
the 10 MHz, REFCKI input (free-run mode). The CLAD reference is configured
by writing to the CMUX[2:0] bits in the Global Control Register [GCR; addr 01].
Free-run mode is selected by writing 1 to the FREE bit in the CLAD
Configuration Register [CLAD_CR; addr 02].
Four CLAD output pins are provided: CLADO, CLK32, CLK1544, and
CLK2048. In Hardware Mode, the CLADO output provides only a fixed 8 kHz
clock. In Host Mode, the CLADO frequency is programmable. Table 2-10 lists
the CLAD outputs and frequencies. For pin definitions, refer to Table 1-1
.
Table 2-10. CLAD Outputs and Frequencies
CLAD Output
Frequency
CLADO
CLK32
CLK1544
CLK2048
Host Mode—Programmable to various frequencies in the range of
8 kHz to 32,768 kHz.
Hardware Mode—Fixed 8 kHz.
Fixed 32,768 kHz
Fixed 1,544 kHz
Fixed 2,048 kHz
2.7.3 Configuration Options
CLAD modes are selected using the CLAD Configuration Register [CLAD_CR;
addr 02]; the CLAD Frequency Select [CSEL; addr 03]; and the CLAD Phase
Detector Scale Factor [CPHASE; addr 04]. The CLAD reference can be any of 41
possible frequencies, as listed in Table 2-11.
2-26
Conexant
N8380DSA
Advance Information