FemtoClocks Crystal-to-3.3V LVPECL 843256I Frequency Synthesizer With Integrated Fanout Buffer DATASHEET GENERAL DESCRIPTION FEATURES The 843256I is a Crystal-to-3.3V LVPECL Clock Synthesizer/Fanout Six 3.3V differential LVPECL output pairs Buffer designed for Fibre Channel and Gigabit Ethernet applications. Output frequency range: 62.5MHz to 625MHz The output frequency can be set using the frequency select pins and Crystal input frequency range: 15.625MHz to 25.5MHz a 25MHz crystal for Ethernet frequencies, or a 19.44MHz crystal for SONET. The low phase noise characteristics of the 843256I make RMS phase jitter at 156.25MHz, using a 25MHz crystal it an ideal clock for these demanding applications. (1.875MHz to 20MHz): 0.41ps (typical) 3.3V Operating supply modes: Core/Output 3.3V/3.3V 3.3V/2.5V -40C to 85C ambient operating temperature Available in lead-free (RoHS 6) package SELECT FUNCTION TABLE Inputs Function FB SEL N SEL1 N SEL0 M Divide N Divide M/N 00 025 1 25 0 0 1 25 2 12.5 0 1 0 25 4 6.25 01 125 5 5 10 032 1 32 10 132 2 16 11 032 4 8 11 132 8 4 PIN ASSIGNMENT BLOCK DIAGRAM 24-Lead TSSOP, E-Pad 4.40mm x 7.8mm x 0.92mm body package G Package Top View 843256I REVISION A 5/29/15 1 2015 Integrated Device Technology, Inc.843256I DATA SHEET TABLE 1. PIN DESCRIPTIONS Number Name Type Description 1, 2 V Power Output supply pins. CCO 3, 4 nQ2, Q2 Output Differential output pair. LVPECL interface levels. 5, 6 nQ1, Q1 Output Differential output pair. LVPECL interface levels. 7, 8 nQ0, Q0 Output Differential output pair. LVPECL interface levels. Selects between the PLL and crystal inputs as the input to the dividers. 9 PLL BYPASS Input Pullup When LOW, selects PLL. When HIGH, selects XTAL IN, XTAL OUT. LVCMOS / LVTTL interface levels. 10 V Power Analog supply pin. CCA 11 V Power Core supply pin. CC 12 FB SEL Input Pulldown Feedback frequency select pin. LVCMOS/LVTTL interface levels. 13, XTAL IN, XTAL Crystal oscillator interface. XTAL IN is the input. Input 14 OUT XTAL OUT is the output. 15, N SEL0 Input Pullup Output frequency select pin. LVCMOS/LVTTL interface levels. 18 N SEL1 16, 17 V Negative supply pin. EE 19, 20 nQ5, Q5 Output Differential output pair. LVPECL interface levels. 21, 22 nQ4, Q4 Output Differential output pair. LVPECL interface levels. 23, 24 nQ3, Q3 Output Differential output pair. LVPECL interface levels. NOTE: Pullup and Pulldown refer 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 Pulldown Resistor 51 k PULLDOWN R Input Pullup Resistor 51 k PULLUP FEMTOCLOCKS CRYSTAL-TO-3.3V LVPECL FREQUENCY 2 REVISION A 5/29/15 SYNTHESIZER WITH/INTEGRATED FANOUT BUFFER