844S012 Datasheet, PDF (1/24 Pages) Integrated Device Technology – Crystal-to-LVDS/LVCMOS Frequency Synthesizer

Crystal-to-LVDS/LVCMOS
Frequency Synthesizer
844S012
DATA SHEET
General Description
The 844S012 is an optimized PCIe, sRIO and Gigabit Ethernet
Frequency Synthesizer. The 844S012 uses a 25MHz parallel
resonant crystal to generate 33.33MHz - 200MHz clock signals,
replacing solutions requiring multiple oscillator and fanout buffer
solution. The device supports ±0.25% center-spread, and -0.6%
down-spread clocking with two spread select pins (SSC[1:0]). The
VCO operates at frequency of 2GHz. The device has three output
banks: Bank A with two LVDS outputs, 100MHz – 250MHz; Bank B
with seven 33.33MHz – 200MHz LVCMOS/ LVTTL outputs; and Bank
C with one 33.33MHz – 200MHz LVCMOS/LVTTL output.
All Banks A, B and C have their own dedicated frequency select pins
and can be independently set for the frequencies mentioned above.
The low jitter characteristic of the 844S012 makes it an ideal clock
source for PCIe, sRIO and Gigabit Ethernet applications. Designed
for networking and industrial applications, the 844S012 can also
drive the high-speed clock inputs of communication processors,
DSPs, switches and bridges.
Features
• Two differential LVDS outputs (Bank A), configurable for PCIe
(100MHz or 250MHz) and sRIO (100MHz or 125MHz) clock
signals
• Eight LVCMOS/LVTTL outputs (Bank B/C), 18 typical output
impedance
• Two REF_OUT LVCMOS/LVTTL clock outputs 23 typical output
impedance
• Selectable crystal oscillator interface, 25MHz, 18pF parallel
resonant crystal or one LVCMOS/LVTTL single-ended reference
clock input
• Supports the following output frequencies:
LVDS Bank A: 100MHz, 125MHz, 200MHz and 250MHz
LVCMOS/LVTTL Bank B/C: 33.33MHz, 50MHz, 66.67MHz,
100MHz, 125MHz, 133.33MHz, 166.67MHz and 200MHz
• VCO: 2GHz
• Spread spectrum clock: ±0.25% center-spread, and
-0.6% down-spread
• PLL bypass and output enable
• RMS period jitter: 17ps (maximum), QB outputs
• Full 3.3V supply voltage
• -40°C to 85°C ambient operating temperature
• Available in a lead-free (RoHS 6) compliant package
• Replacement part: 844S012BKI-01LF/T
844S012 REVISION B 08/25/15
Pin Assignment
V_DD
REF_OUT0
REF_OUT1
GND
GND
REF_IN
VDD
REF_SEL
XTAL_IN
XTAL_OUT
BYPASS
REF_OE
nMR
V_DD
56 55 54 53 52 51 50 49 48 47 46 45 44 43
1
42
2
41
3
40
4
844S012
39
5
56-Lead VFQFN
38
6
7
8mm x 8mm x 0.925mm
37
36
8
package body
35
9
K Package
34
10
Top View
33
11
32
12
31
13
30
14
29
15 16 17 18 19 20 21 22 23 24 25 26 27 28
V_DDOC
QC
GND
QBC_OE
VDDA
V_DDA
GND
GND
GND
QA0
nQA0
QA1
nQA1
VDD
1
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