874002数据手册集成电路（IC）的应用特定时钟/定时规格书PDF

描述 Description

The 874002 is a high performance Differential-to-LVDS Jitter Attenuator designed for use in PCI Express® systems. In some PCI Express® systems, such as those found in desktop PCs, the PCI Express® clocks are generated from a low bandwidth, high phase noise PLL frequency synthesizer. In these systems, a jitter attenuator may be required to attenuate high frequency random and deterministic jitter components from the PLL synthesizer and from the system board. The 874002 has 3 PLL bandwidth modes: 200kHz, 400kHz, and 800kHz. The 200kHz mode will provide maximum jitter attenuation, but with higher PLL tracking skew and spread spectrum modulation from the motherboard synthesizer may be attenuated. The 400kHz provides an intermediate bandwidth that can easily track triangular spread profiles, while providing good jitter attenuation. The 800kHz bandwidth provides the best tracking skew and will pass most spread profiles, but the jitter attenuation will not be as good as the lower bandwidth modes. Because some 2.5Gb serdes have x20 multipliers while others have than x25 multipliers, the 874002 can be set for 1:1 mode or 5/4 multiplication mode (i.e. 100MHz input/125MHz output) using the F_SEL pin. The 874002 uses IDT's 3rd Generation FemtoClockTM PLL technology to achieve the lowest possible phase noise. The device is packaged in a 20 Lead TSSOP package, making it ideal for use in space constrained applications such as PCI Express® add-in cards.

特性 Features

Two differential LVDS output pair
One differential clock input
CLK and nCLK supports the following input types: LVPECL, LVDS, LVHSTL, SSTL, HCSL
Output frequency range: 98MHz - 160MHz
Input frequency range: 98MHz - 128MHz
VCO range: 490MHz - 640MHz
Cycle-to-cycle jitter: 35ps (maximum)
3.3V operating supply
Three bandwidth modes allow the system designer to make jitter attenuation/tracking skew design trade-offs
0°C to 70°C ambient operating temperature
Available in lead-free (RoHS 6) package