General Description

The IDT8T49N203I is a highly flexible FemtoClock® NG general

purpose, low phase noise Universal Frequency Translator /

Synthesizer with alarm and monitoring functions suitable for

networking and communications applications. It 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 and a range of

low-cost fundamental mode crystal frequencies may be used as the

source for the output frequency.

The IDT8T49N203I has three operating modes to support a very

broad spectrum of applications:

1) Frequency Synthesizer

• Synthesizes output frequencies from a 16MHz - 40MHz

fundamental mode crystal.

• Fractional feedback division is used, so there are no

requirements for any specific crystal 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, so it will not attenuate much jitter on the input

reference.

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 crystal to provide

significant jitter attenuation.

Features

• Fourth generation FemtoClock® NG technology

• Universal Frequency Translator (UFT) / Frequency Synthesizer

• Two outputs, individually programmable as LVPECL or LVDS

• Both outputs may be set to use 2.5V or 3.3V output levels

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

• Zero ppm frequency translation

• Two differential inputs support the following input types:

LVPECL, LVDS, LVHSTL, HCSL

• Input frequency range: 8kHz - 710MHz

• Crystal input frequency range: 16MHz - 40MHz

• Two factory-set register configurations for power-up default state

• Power-up default configuration pin or register selectable

• Configurations customized via One-Time Programmable ROM

• Settings may be overwritten after power-up via I2C

• I2C Serial interface for register programming

• RMS phase jitter at 155.52MHz, using a 40MHz crystal LVDS

Output (12kHz - 20MHz): 439fs (typical), Low Bandwidth Mode

(FracN)

• RMS phase jitter at 400MHz, using a 40MHz crystal

(12kHz - 40MHz):285fs (typical), Synthesizer Mode (Integer FB)

• Output supply voltage 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

• Available in lead-free (RoHS 6) package