DS26502 Maxim Integrated Products, DS26502 Datasheet - Page 80

• Manufacturer Part Number: DS26502
• Description: T1/E1/J1/64KCC BITS Element
• Manufacturer: Maxim Integrated Products

DS26502 T1/E1/J1/64KCC BITS Element
32.768MHz (E1) or 24.704MHz (T1) clock by either 15 or 17 instead of the normal 16 to keep the buffer
from overflowing. When the device divides by either 15 or 17, it also sets the Jitter Attenuator Limit Trip
(JALT) bit in Status Register 1 (SR1.4).
13.6 CMI (Code Mark Inversion) Option
The DS26502 provides a CMI interface for connection to optical transports. This interface is a unipolar
1T2B type of signal. Ones are encoded as either a logical one or zero level for the full duration of the
clock period. Zeros are encoded as a zero-to-one transition at the middle of the clock period.
Figure 13-3. CMI Coding
CLOCK
1
1
0
1
0
0
1
DATA
CMI
Transmit and receive CMI is enabled via LIC4.7. When this register bit is set, the TTIP pin will output
CMI-coded data at normal levels. This signal can be used to directly drive an optical interface. When
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CMI is enabled, the user can also use HDB3/B8ZS coding. When this register bit is set, the RTIP pin will
become a unipolar CMI input. The CMI signal will be processed to extract and align the clock with data.
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