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.

特性 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