General Description

The 845264 is a 3.3V, 2.5V CML clock generator designed for

Ethernet applications. The device synthesizes four clock frequencies

on two separately selectable output banks. Each bank has either a

62.5MHz, 125MHz, 156.25MHz or 312.5MHz clock signal with

excellent phase jitter performance. Each clock frequency is

distributed to two low-skew differential CML output banks with a total

of four outputs. The device is suitable for driving the reference clocks

of Ethernet PHYs. The device supports 3.3V and 2.5V voltage

supply and is packaged in a small, lead-free (RoHS 6) 32-lead

VFQFN package. The extended temperature range supports

telecommunication, wireless infrastructure and networking end

equipment requirements.

Features

• Clock generation of: 62.5MHz, 125MHz, 156.25MHz and

312.5MHz

• Two banks of two differential CML clock outputs

• Crystal interface designed for 25MHz, 12pF parallel resonant

crystal

• RMS phase jitter @ 125MHz, using a 25MHz crystal

(1.875MHz – 20MHz): 0.486ps (typical)

Offset Single-side Band Phase Noise

100Hz ............................-97 dBc/Hz

1kHz...............................-118 dBc/Hz

10kHz.............................-125 dBc/Hz

100kHz...........................-123 dBc/Hz

• LVCMOS interface levels for the control inputs

• Full 3.3V and 2.5V supply voltage

• Lead-free (RoHS 6) 32 VFQFN packaging

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