844008I-46 Datasheet, PDF (1/16 Pages) Integrated Device Technology – FemtoClock Crystal-to-LVDS Clock Generator

FemtoClock^® Crystal-to-LVDS
Clock Generator
844008I-46
DATA SHEET
GENERAL DESCRIPTION
The 844008I-46 is a 10Gb Ethernet Clock Generator and a member
of the HiPerClocks™ family of high performance devices from
IDT. The 844008I-46 can synthesize 156.25MHz or 100MHz with
a 25MHz crystal. It has a total of 8 LVDS outputs. The 844008I-46
has excellent phase jitter performance and is packaged in a 32
Lead VFQFN package, making it ideal for use in systems with
limited board space.
FEATURES
• Eight differential LVDS outputs
• Crystal oscillator interface designed for 18pF parallel resonant
crystals
• Supports the following output frequencies:
156.25MHz or 100MHz
• VCO frequency: 625MHz or 600MHz
• RMS phase jitter @ 156.25MHz, using a 25MHz crystal
(1.875MHz - 20MHz): 0.45ps (typical)
• Full 2.5V supply mode
• -40°C to 85°C ambient operating temperature
• Available in lead-free (RoHS 6) packages
• For functional replacement part use 8T49N285
FREQUENCY SELECT FUNCTION TABLE
Input
XTAL Frequency
(MHz)
25
25
FREQ_SEL
0
1
FB Divider
÷25
÷24
Output Divider
÷4
÷6
VCO (MHz)
625
600
Output Frequency (MHz)
156.25 (default)
100
BLOCK DIAGRAM
OE ^Pullup
25MHz
XTAL_IN
OSC
Phase
VCO
÷4
XTAL_OUT
Detector 625MHz or
or
600MHz
÷6
FREQ_SEL ^Pulldown
FB = ÷25 or ÷24
PIN ASSIGNMENT
8 _Q0:Q7
8 _nQ0:nQ7
32 31 30 29 28 27 26 25
Q0 ₁
24 ^nc
nQ0 ₂
23 ^OE
GND ₃ ICS844008I-46 ₂₂ ^GND
Q1
nQ1
4
5mm
32-Lead VFQFN
x 5mm x 0.925mm
pac²k¹-
5
age body
20
nQ7
Q7
VDDO ₆
K Package
19 ^VDDO
Q2 ₇
Top View
18 ^nQ6
nQ2 ₈
17 ^Q6
9 10 11 12 13 14 15 16
844008I-46 REVISION A 11/6/15
1
©2015 Integrated Device Technology, Inc.