Si550
R
EVISION
D
V
O L TAG E
- C
ONTR OLLED
C
RYSTAL
O
S C I L L A T O R
(VCXO)
10 MH
Z TO
1.4 G H
Z
Features
Available with any frequency from
10 to 945 MHz and select
frequencies to 1.4 GHz
3rd generation DSPLL
®
with
superior jitter performance (0.5 ps)
3x better temperature stability than
SAW-based oscillators
Excellent PSRR performance
Internal fixed crystal frequency
ensures high reliability and low
aging
Available CMOS, LVPECL,
LVDS, and CML outputs
3.3, 2.5, and 1.8 V supply options
Industry-standard 5 x 7 mm
package and pinout
Pb-free/RoHS-compliant
Si5602
Ordering Information:
See page 9.
Applications
SONET/SDH
xDSL
10 GbE LAN/WAN
Low-jitter clock generation
Optical modules
Clock and data recovery
Pin Assignments:
See page 8.
(Top View)
V
C
1
6
V
DD
Description
The Si550 VCXO utilizes Silicon Laboratories’ advanced DSPLL
®
circuitry to
provide a low-jitter clock at high frequencies. The Si550 supports any
frequency from 10 to 945 MHz and select frequencies to 1417 MHz. Unlike
traditional VCXOs, where a different crystal is required for each output
frequency, the Si550 uses one fixed crystal to provide a wide range of output
frequencies. This IC-based approach allows the crystal resonator to provide
exceptional frequency stability and reliability. In addition, DSPLL clock
synthesis provides superior supply noise rejection, simplifying the task of
generating low-jitter clocks in noisy environments typically found in
communication systems. The Si550 IC-based VCXO is factory-configurable
for a wide variety of user specifications, including frequency, supply voltage,
output format, tuning slope, and temperature stability. Specific configurations
are factory programmed at time of shipment, thereby eliminating the long
lead times associated with custom oscillators.
OE
2
5
CLK–
GND
3
4
CLK+
Functional Block Diagram
V
DD
Fixed
Frequency
XO
Any-Frequency
10 MHz–1.4 GHz
DSPLL
®
Clock Synthesis
CLK+
CLK–
Vc
ADC
OE
GND
Rev. 1.0 1/12
Copyright © 2012 by Silicon Laboratories
Si550
Si550
1. Electrical Specifications
Table 1. Recommended Operating Conditions
Parameter
Supply Voltage
1
Symbol
V
DD
Test Condition
3.3 V option
2.5 V option
1.8 V option
Supply Current
I
DD
Output enabled
LVPECL
CML
LVDS
CMOS
tristate mode
Output Enable (OE)
2
Operating Temperature Range
T
A
V
IH
V
IL
Min
2.97
2.25
1.71
—
—
—
—
—
0.75 x V
DD
—
–40
Typ
3.3
2.5
1.8
120
108
99
90
60
—
—
—
Max
3.63
2.75
1.89
130
117
108
98
75
—
0.5
85
Units
V
V
V
mA
mA
V
V
°C
Notes:
1.
Selectable parameter specified by part number. See 3. "Ordering Information" on page 9 for further details.
2.
OE pin includes a 17 k resistor to V
DD
.
Table 2. V
C
Control Voltage Input
Parameter
Control Voltage Tuning Slope
1,2,3
Symbol
K
V
Test Condition
10 to 90% of V
DD
Min
—
—
—
—
—
—
–5
–10
9.3
500
@ f
O
—
0
Typ
33
45
90
135
180
356
±1
±5
10.0
—
V
DD
/2
Max
—
—
—
—
—
—
+5
+10
10.7
—
—
V
DD
Units
ppm/V
Control Voltage Linearity
4
L
VC
BW
Z
VC
V
CNOM
V
C
BSL
Incremental
%
%
kHz
k
V
V
Modulation Bandwidth
V
C
Input Impedance
Nominal Control Voltage
Control Voltage Tuning Range
Notes:
1.
Positive slope; selectable option by part number. See 3. "Ordering Information" on page 9.
2.
For best jitter and phase noise performance, always choose the smallest K
V
that meets the application’s minimum APR
requirements. See “AN266: VCXO Tuning Slope (K
V
), Stability, and Absolute Pull Range (APR)” for more information.
3.
K
V
variation is ±10% of typical values.
4.
BSL determined from deviation from best straight line fit with V
C
ranging from 10 to 90% of V
DD
. Incremental slope
determined with V
C
ranging from 10 to 90% of V
DD
.
2
Rev. 1.0
Si550
Table 3. CLK± Output Frequency Characteristics
Parameter
Nominal Frequency
1,2,3
Temperature Stability
1,4
Symbol
f
O
Test Condition
LVDS/CML/LVPECL
CMOS
T
A
= –40 to +85 ºC
Min
10
10
–20
–50
–100
±12
Frequency drift over first year.
Frequency drift over 15 year life.
Power up Time
5
t
OSC
Typ
—
—
—
—
—
—
—
—
—
Max
945
160
+20
+50
+100
±375
±3
±10
10
Units
MHz
MHz
ppm
ppm
ppm
ms
Absolute Pull Range
1,4
Aging
APR
—
—
—
Notes:
1.
See Section 3. "Ordering Information" on page 9 for further details.
2.
Specified at time of order by part number. Also available in frequencies from 970 to 1134 MHz and 1213 to 1417 MHz.
3.
Nominal output frequency set by V
CNOM
= V
DD
/2.
4.
Selectable parameter specified by part number.
5.
Time from power up or tristate mode to f
O
.
Table 4. CLK± Output Levels and Symmetry
Parameter
LVPECL Output Option
1
Symbol
V
O
V
OD
V
SE
Test Condition
mid-level
swing (diff)
swing (single-ended)
mid-level
swing (diff)
Min
V
DD
– 1.42
1.1
0.55
1.125
0.5
Typ
—
Max
V
DD
– 1.25
1.9
0.95
1.275
0.9
Units
V
V
PP
V
PP
V
V
PP
—
—
1.20
0.7
LVDS Output Option
2
V
O
V
OD
V
O
2.5/3.3 V option mid-level
1.8 V option mid-level
2.5/3.3 V option swing (diff)
1.8 V option swing (diff)
I
OH
= 32 mA
I
OL
= 32 mA
—
—
1.10
0.35
0.8 x V
DD
V
DD
– 1.30
V
DD
– 0.36
1.50
0.425
—
—
—
1
—
—
—
1.90
0.50
V
DD
V
V
V
PP
V
PP
CML Output Option
2
V
OD
CMOS Output Option
3
Rise/Fall time (20/80%)
Symmetry (duty cycle)
V
OH
V
OL
t
R,
t
F
V
V
—
—
—
45
0.4
350
—
55
LVPECL/LVDS/CML
CMOS with C
L
= 15 pF
LVPECL:
LVDS:
CMOS:
V
DD
– 1.3 V (diff)
1.25 V (diff)
V
DD
/2
ps
ns
%
SYM
Notes:
1.
50
to V
DD
– 2.0 V.
2.
R
term
= 100
(differential).
3.
C
L
= 15 pF
Rev. 1.0
3
Si550
Table 5. CLK± Output Phase Jitter
Parameter
Phase Jitter (RMS)
1,2,3
for F
OUT
> 500 MHz
Symbol
Test Condition
Kv = 33 ppm/V
12 kHz to 20 MHz (OC-48)
50 kHz to 80 MHz (OC-192)
Kv = 45 ppm/V
12 kHz to 20 MHz (OC-48)
50 kHz to 80 MHz (OC-192)
Kv = 90 ppm/V
12 kHz to 20 MHz (OC-48)
50 kHz to 80 MHz (OC-192)
Kv = 135 ppm/V
12 kHz to 20 MHz (OC-48)
50 kHz to 80 MHz (OC-192)
Kv = 180 ppm/V
12 kHz to 20 MHz (OC-48)
50 kHz to 80 MHz (OC-192)
Kv = 356 ppm/V
12 kHz to 20 MHz (OC-48)
50 kHz to 80 MHz (OC-192)
Min
—
—
—
—
—
—
—
—
—
—
—
—
Typ
0.26
0.26
0.27
0.26
0.32
0.26
0.40
0.27
0.49
0.28
0.87
0.33
Max
—
—
—
—
—
—
—
—
—
—
—
—
Units
ps
J
ps
ps
ps
ps
ps
Notes:
1.
Refer to AN255, AN256, and AN266 for further information.
2.
For best jitter and phase noise performance, always choose the smallest K
V
that meets the application’s minimum APR
requirements. See “AN266: VCXO Tuning Slope (K
V
), Stability, and Absolute Pull Range (APR)” for more information.
3.
See “AN255: Replacing 622 MHz VCSO devices with the Si550 VCXO” for comparison highlighting power supply
rejection (PSR) advantage of Si55x versus SAW-based solutions.
4.
Max jitter for LVPECL output with V
C
=1.65V, V
DD
=3.3V, 155.52 MHz.
5.
Max offset frequencies: 80 MHz for F
OUT
> 250 MHz, 20 MHz for 50 MHz < F
OUT
<250 MHz,
2 MHz for 10 MHz < F
OUT
<50 MHz.
4
Rev. 1.0
Si550
Table 5. CLK± Output Phase Jitter (Continued)
Parameter
Phase Jitter (RMS)
1,2,3,4,5
for F
OUT
of 125 to 500 MHz
Symbol
Test Condition
Kv = 33 ppm/V
12 kHz to 20 MHz (OC-48)
50 kHz to 80 MHz (OC-192)
Kv = 45 ppm/V
12 kHz to 20 MHz (OC-48)
50 kHz to 80 MHz (OC-192)
Kv = 90 ppm/V
12 kHz to 20 MHz (OC-48)
50 kHz to 80 MHz (OC-192)
Kv = 135 ppm/V
12 kHz to 20 MHz (OC-48)
50 kHz to 80 MHz (OC-192)
Kv = 180 ppm/V
12 kHz to 20 MHz (OC-48)
50 kHz to 80 MHz (OC-192)
Kv = 356 ppm/V
12 kHz to 20 MHz (OC-48)
50 kHz to 80 MHz (OC-192)
Min
—
—
—
—
—
—
—
—
—
—
—
—
Typ
0.37
0.33
0.37
0.33
0.43
0.34
0.50
0.34
0.59
0.35
1.00
0.39
Max
—
—
0.4
—
—
—
—
—
—
—
—
—
Units
ps
J
ps
ps
ps
ps
ps
Notes:
1.
Refer to AN255, AN256, and AN266 for further information.
2.
For best jitter and phase noise performance, always choose the smallest K
V
that meets the application’s minimum APR
requirements. See “AN266: VCXO Tuning Slope (K
V
), Stability, and Absolute Pull Range (APR)” for more information.
3.
See “AN255: Replacing 622 MHz VCSO devices with the Si550 VCXO” for comparison highlighting power supply
rejection (PSR) advantage of Si55x versus SAW-based solutions.
4.
Max jitter for LVPECL output with V
C
=1.65V, V
DD
=3.3V, 155.52 MHz.
5.
Max offset frequencies: 80 MHz for F
OUT
> 250 MHz, 20 MHz for 50 MHz < F
OUT
<250 MHz,
2 MHz for 10 MHz < F
OUT
<50 MHz.
Rev. 1.0
5
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