FemtoClock Crystal-to-LVDS 844021-01 Clock Generator DATA SHEET GENERAL DESCRIPTION FEATURES The 844021-01 is an Ethernet Clock Generator. The 844021-01 One Differential LVDS output uses an 18pF parallel resonant crystal over the range of 24.5MHz Crystal oscillator interface, 18pF parallel resonant crystal 34MHz. For Ethernet applications, a 25MHz crystal is used. The (24.5MHz 34MHz) 844021-01 has excellent <1ps phase jitter performance, over the Output frequency range: 122.5MHz 170MHz 1.875MHz 20MHz integration range. The 844021-01 is packaged in a small 8-pin TSSOP, making it ideal for use in systems with VCO range: 490MHz 680MHz limited board space. RMS phase jitter 125MHz, using a 25MHz crystal (1.875MHz 20MHz): 0.32ps (typical) 3.3V 3.3V or 2.5V operating supply 0C to 70C ambient operating temperature Available in lead-free (RoHS 6) package COMMON CONFIGURATION TABLE - Gb ETHERNET Inputs Output Frequency Multiplication (MHz) Crystal Frequency (MHz) M N Value M/N 25 20 4 5 125 26.666 20 4 5 133.33 33.33 20 4 5 166.66 BLOCK DIAGRAM PIN ASSIGNMENT Pullup OE VDDA 1 8 VDD GND 2 7 Q XTAL OUT 3 6 nQ XTAL IN Q XTAL IN 4 5 OE VCO Phase OSC N = 4 (fixed) 490MHz - 680MHz nQ Detector XTAL OUT 844021-01 8-Lead TSSOP 4.40mm x 3.0mm x 0.925mm M = 20 (fixed) package body G Package Top View 844021-01 REVISION A 10/26/15 1 2015 Integrated Device Technology, Inc.844021-01 DATA SHEET TABLE 1. PIN DESCRIPTIONS Number Name Type Description 1V Power Analog supply pin. DDA 2 GND Power Power supply ground. 3, XTAL OUT, Crystal oscillator interface. XTAL IN is the input, Input 4 XTAL IN XTAL OUT is the output. Output enable pin. When HIGH, Q/nQ output is active. 5 OE Input Pullup When LOW, the Q/nQ output is in a high impedance state. LVCMOS/LVT- TL interface levels. 6, 7 nQ, Q Output Differential clock outputs. LVDS interface levels. 8V Power Core supply pin. DD NOTE: Pullup refers to internal input resistors. See Table 2, Pin Characteristics, for typical values. TABLE 2. PIN CHARACTERISTICS Symbol Parameter Test Conditions Minimum Typical Maximum Units C Input Capacitance 4 pF IN R Input Pullup Resistor 51 k PULLUP FEMTOCLOCKS CRYSTAL-TO-LVDS 2 REVISION A 10/26/15 CLOCK GENERATOR