ds3104-se Maxim Integrated Products, Inc., ds3104-se Datasheet - Page 19

• Manufacturer Part Number: ds3104-se
• Description: Line Card Timing Ic With Synchronous Ethernet Support
• Manufacturer: Maxim Integrated Products, Inc.

7.4
The DS3104-SE has eight input clocks, IC1 to IC6 and IC8 and IC9.
each clock, including signal format and available frequencies. The device tolerates a wide range of duty cycles on
input clocks, out to a minimum high time or minimum low time of 3ns or 30% of the clock period, whichever is
smaller.
7.4.1 Signal Format Configuration
Inputs with CMOS/TTL signal format accept both TTL and 3.3V CMOS levels. One key configuration bit that affects
the available frequencies is the SONSDH bit in MCR3. When SONSDH = 1 (SONET mode), the 1.544MHz
frequency is available. When SONSDH = 0 (SDH mode), the 2.048MHz frequency is available. During reset the
default value of this bit is latched from the SONSDH pin.
Input clocks IC1, IC2, IC5, and IC6 can be configured to accept LVDS, LVPECL, or CMOS/TTL signals by using
the proper set of external components. The recommended LVDS termination is shown in
recommended LVPECL termination is shown in
in
divider to bias the ICxNEG pin to approximately 1.4V and connect the single-ended signal to the ICxPOS pin. If a
differential input is not used it should be configured left floating (one input is internally pulled high and the other
internally pulled low). (See also MCR5:IC5SF and IC6SF.)
Table 7-1. Input Clock Capabilities
Note 1: Available frequencies for CMOS/TTL input clocks are: 2kHz, 4kHz, 8kHz, 1.544MHz (SONET mode), 2.048MHz (SDH mode),
6.312MHz, 6.48MHz, 19.44MHz, 25.0MHz, 25.92MHz, 38.88MHz, 51.84MHz, 62.5MHz, 77.76MHz, and any multiple of 2kHz up to 125MHz.
Note 2: Available frequencies for LVDS/LVPECL input clocks include all CMOS/TTL frequencies in Note 1 plus any multiple of 8kHz up to
155.52MHz and 156.25MHz.
________________________________________________________________________________________ DS3104-SE
INPUT CLOCK
Table
IC1
IC2
IC3
IC4
IC5
IC6
IC8
IC9
Input Clock Configuration
10-4. To configure these differential inputs to accept single-ended CMOS/TTL signals, use a voltage-
LVDS/LVPECL or CMOS/TTL
LVDS/LVPECL or CMOS/TTL
LVDS/LVPECL or CMOS/TTL
LVDS/LVPECL or CMOS/TTL
SIGNAL FORMATS
CMOS/TTL
CMOS/TTL
CMOS/TTL
CMOS/TTL
Figure
10-2. The electrical specifications for these inputs are listed
FREQUENCIES (MHz)
Up to 156.25
Up to 156.25
Up to 156.25
Up to 156.25
Up to 125
Up to 125
Up to 125
Up to 125
Table 7-1
(1)
(1)
(1)
(1)
(2)
(2)
(2)
(2)
provides summary information about
DEFAULT FREQUENCY
Figure 10-1
19.44MHz
19.44MHz
19.44MHz
19.44MHz
8kHz
8kHz
8kHz
8kHz
while the
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