General Description

The IDT8T49N244I is a dual PLL using FemtoClock? NG

technology. It integrates low phase noise Frequency Translation /

Synthesis and Jitter attenuation. It includes alarm and monitoring

functions suitable for networking and communications applications.

The device has two fully independent PLLs. Each PLL is able to

generate any output frequency in the 0.98MHz - 312.5MHz range

and most output frequencies in the 312.5MHz - 1,300MHz range

(see Table 3 for details). A wide range of input reference clocks may

be used as the source for the output frequencies.

Each PLL of IDT8T49N244I has three operating modes to support a

very broad spectrum of applications:

1) Frequency Synthesizer

? Synthesizes output frequencies from an external reference

clock REFCLK.

? Fractional feedback division is used, so there are no

requirements for any specific input reference clock frequency to

produce the desired output frequency with a high degree of

accuracy.

2) High-Bandwidth Frequency Translator

? Applications: PCI Express, Computing, General Purpose

? Translates any input clock in the 16MHz - 710MHz frequency

range into any supported output frequency.

? This mode has a high PLL loop bandwidth in order to track input

reference changes, such as Spread-Spectrum Clock

modulation.

3) Low-Bandwidth Frequency Translator

? Applications: Networking & Communications.

? Translates any input clock in the 8kHz -710MHz frequency

range into any supported output frequency.

? This mode supports PLL loop bandwidths in the 10Hz - 580Hz

range and makes use of an external REFCLK to provide

significant jitter attenuation.

特性 Features

? Fourth generation FemtoClock? NG technology

? Two fully independent PLLs

? Universal Frequency TranslatorTM/Frequency Synthesizer and

Jitter attenuator

? Outputs are programmable as LVPECL or LVDS

? Programmable output frequency: 0.98MHz up to 1,300MHz

? Two differential inputs per PLL support the following input types:

LVPECL, LVDS, LVHSTL, HCSL

? Input frequency range: 8kHz - 710MHz (Low-Bandwidth mode)

? Input frequency range: 16MHz - 710MHz (High-Bandwidth mode)

? REFCLK frequency range: 16MHz - 40MHz

? Input clock monitor on each PLL will smoothly switch between

redundant input references

? Factory-set register configuration for power-up default state

? Power-up default configuration

? Configuration customized via One-Time Programmable ROM

? Settings may be overwritten after power-up via I2C

? I

2C Serial interface for register programming

? RMS phase jitter at 161.1328125MHz, using a 40MHz REFCLK

(12kHz - 20MHz): 486fs (typical), Low Bandwidth Mode (FracN)

? RMS phase jitter at 400MHz, using a 40MHz REFCLK

(12kHz - 20MHz): 326fs (typical), Synthesizer Mode (Integer FB)

? Supply modes:

VCC / VCCA / VCCO

3.3V / 3.3V / 3.3V

3.3V / 3.3V / 2.5V (LVPECL only)

2.5V / 2.5V / 2.5V

? -40°C to 85°C ambient operating temperature

? 10mm X 10mm CABGA package

? Lead-free (RoHS 6) packaging