General Description

The 8741004 is a high performance Differential-to-LVDS/0.7V

Differential 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 8741004 has 3 PLL

bandwidth modes: 200kHz, 600kHz and 2MHz. 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 600kHz provides an

intermediate bandwidth that can easily track triangular spread

profiles, while providing good jitter attenuation. The 2MHz 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 x25 multipliers, the 8741004 can be set for 1:1 mode or

5/4 multiplication mode (i.e. 100MHz input/125MHz output) using the

F_SEL pins.

The 8741004 uses IDT’s 3rd Generation FemtoClock™

PLL technology to achieve the lowest possible phase noise.

The device is packaged in a 24 Lead TSSOP package, making it

ideal for use in space constrained applications such as PCI Express

add-in cards.

Features

• Two LVDS and two 0.7V differential output pairs

Bank A has two LVDS output pairs and

Bank B has two 0.7V differential output pairs

• One differential clock input pair

• CLK, CLK pair can accept the following differential

input levels: 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)

• Full 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