General Description
The 8T49N028 is a low RMS phase jitter Clock Synthesizer with
selectable internal crystal oscillator or external clock references and
eight outputs, configurable as either LVDS, LVPECL or High
Impedance.
After power up, two frequency select pins determine one of up to four
different sets of factory preprogrammed crystal or input frequency
and output frequency configurations. From a single input reference,
as many as three different output frequencies may be selected for
the output banks: two of these frequencies can be generated by the
internal crystal oscillator, and/or external clock pre-divider, and/or A
output divider, and/or B output divider. The third output frequency is
from the B output divider. Device pre-programming can be
overwritten through the provided I2C interface.
Examples of valid frequency configuration setups illustrate this
device's flexibility, and are shown in Table 3A. The specific internal
register settings for each of the four frequency sets are specified by
an IDT order code. Custom codes can be provided by contacting
IDT.

Features
• Fourth Generation FemtoClock NG PLL technology
• Eight selectable LVPECL or LVDS outputs (bank selectable, two
output channels per bank)
• CLK, nCLK input pair can accept the following differential input
levels: LVPECL, LVDS, HCSL
• FemtoClock NG VCO Range: 1.92GHz - 2.5GHz
• Bank A and B output frequencies are mux selectable from internal
crystal oscillator, reference clock input, output divider A or output
divider B
• Clock from OUTPUT DIVIDER A, RMS phase jitter at 156.25MHz
(12KHz - 20MHz): 225fs (typical)
• Clock from OUTPUT DIVIDER B, RMS phase jitter at 156.25MHz
(12KHz - 20MHz): 219fs (typical)
• Clock from OUTPUT DIVIDER B, RMS phase jitter at 156.25MHz
(10kHz - 1MHz): 165fs (typical) Full 2.5V or 3.3V power supply
• Full 2.5V or 3.3V power supply
• I
2C programming interface
• PCI Express (2.5 Gb/S), Gen 2 (5 Gb/s) and Gen 3 (8 Gb/s) jitter
compliant
• -40°C to 85°C ambient operating temperature
• Lead-free (RoHS 6) packaging