844441 Datasheet, PDF (1/15 Pages) Integrated Device Technology – FemtoClock SAS/ SATA Clock Generator

FemtoClock® SAS/ SATA Clock Generator
844441
Datasheet
General Description
The 844441 is a low jitter, high performance clock generator and a
member of the FemtoClock^® family of silicon timing products. The
844441 is designed for use in applications using the SAS and SATA
interconnect. The 844441 uses an external, 25MHz, parallel
resonant crystal to generate four selectable output frequencies:
75MHz, 100MHz, 150MHz, and 300MHz. This silicon based
approach provides excellent frequency stability and reliability. The
844441 features down and center spread spectrum (SSC) clocking
techniques.
Applications
• SAS/SATA Host Bus Adapters
• SATA Port Multipliers
• SAS I/O Controllers
• TapeDrive and HDD Array Controllers
• SAS Edge and Fanout Expanders
• HDDs and TapeDrives
• Disk Storage Enterprise
Features
• Designed for use in SAS, SAS-2, and SATA systems
• Center (±0.17%) Spread Spectrum Clocking (SSC)
• Down (-0.23% or -0.5%) SSC
• Better frequency stability than SAW oscillators
• One differential 2.5V LVDS output
• Crystal oscillator interface designed for 25MHz
(C_L = 12pF) frequency
• External fundamental crystal frequency ensures high reliability
and low aging
• Selectable output frequencies: 75MHz, 100MHz, 150MHz,
300MHz
• Output frequency is tunable with external capacitors
• RMS phase jitter @ 100MHz, using a 25MHz crystal
(12kHz – 20MHz): 1.1936ps (typical)
• 2.5V operating supply
• -40°C to 85°C ambient operating temperature
• Lead-free (RoHS 6) packaging
Block Diagrams
XTAL_IN
25MHz
XTAL
XTAL_OUT
OSC
SSC_SEL(1:0) ^{Pulldown:Pulldown}
FemtoClock™
PLL
SSC Output
Control Logic
00 = SSC Off
01 = 0.5% Down-spread
Q
10 = 0.23% Down-spread
nQ
11 = 0.5% Center-spread
8-Lead SOIC
nPLL_SEL ^Pulldown
XTAL_IN
25MHz
XTAL
OSC
FemtoClock™
PLL
0
00 = 75MHz
XTAL_OUT
01 = 100MHz
Q
1
10 = 150MHz (default)
nQ
11 = 300MHz
F_SEL(1:0) ^{Pullup:Pulldown}
SSC_SEL(1:0) ^{Pulldown:Pulldown}
Clock Output
Control Logic
16-Lead TSSOP
Pin Assignment
XTAL_OUT 1
XTAL_IN 2
SSC_SEL0 ³
SSC_SEL1 ⁴
8 GND
7 nQ
6Q
5 _VDD
844441
8-Lead SOIC, 3.90mm x 4.90mm Package
GND 1
XTAL_OUT 2
XTAL_IN 3
SSC_SEL0 4
nc ₅
nc 6
nc 7
SSC_SEL1 8
16 F_SEL1
15 ^GND
14 nPLL_SEL
13 nQ
12 Q
11 V_DD
10 F_SEL0
9 V_DD
844441
16-Lead TSSOP, 4.4mm x 5.0mm Package
©2016 Integrated Device Technology, Inc.
1
Revison E, November 2, 2016