Si 5 7 0 / S i 5 7 1
10 MH
Z TO
1.4 G H
Z
I
2
C P
ROGRAMMABLE
XO/VCXO
Features
Any programmable output
frequencies from 10 to 945 MHz and
select frequencies to 1.4 GHz
I
2
C serial interface
3rd generation DSPLL
®
with superior
jitter performance
3x better frequency stability than
SAW-based oscillators
Internal fixed crystal frequency
ensures high reliability and low
aging
Available LVPECL, CMOS,
LVDS, and CML outputs
Industry-standard 5x7 mm
package
Pb-free/RoHS-compliant
1.8, 2.5, or 3.3 V supply
Si5602
Applications
Ordering Information:
SONET/SDH
xDSL
10 GbE LAN/WAN
ATE
High performance
instrumentation
Low-jitter clock generation
Optical modules
Clock and data recovery
See page 32.
Pin Assignments:
See page 31.
(Top View)
SDA
7
NC
1
6
V
DD
Description
The Si570 XO/Si571 VCXO utilizes Silicon Laboratories’ advanced DSPLL
®
circuitry to provide a low-jitter clock at any frequency. The Si570/Si571 are user-
programmable to any output frequency from 10 to 945 MHz and select frequencies
to 1400 MHz with <1 ppb resolution. The device is programmed via an I
2
C serial
interface. Unlike traditional XO/VCXOs where a different crystal is required for
each output frequency, the Si57x uses one fixed-frequency crystal and a DSPLL
clock synthesis IC to provide any-frequency operation. 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.
OE
2
5
CLK–
GND
3
8
SCL
4
CLK+
Functional Block Diagram
V
DD
CLK-
CLK+
Si570
SDA
7
OE
Fixed
Frequency
XO
10-1400 MHz
DSPLL Clock
Synthesis
V
C
1
6
V
DD
SDA
SCL
OE
2
5
CLK–
Si571 only
ADC
GND
3
8
SCL
4
CLK+
GND
V
C
Si571
Si570/Si571
Rev. 1.5 4/14
Copyright © 2014 by Silicon Laboratories
Si570/Si571
T
ABLE O F
C
ONTENTS
Section
Page
1. Detailed Block Diagrams . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4
2. Electrical Specifications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .5
3. Functional Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
3.1. Programming a New Output Frequency . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
3.2. Si570 Programming Procedure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
3.3. Si570 Troubleshooting FAQ . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21
3.4. I2C Interface . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22
4. Serial Port Registers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23
5. Si570 (XO) Pin Descriptions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30
6. Si571 (VCXO) Pin Descriptions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31
7. Ordering Information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32
8. Si57x Mark Specification . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .33
9. Outline Diagram and Suggested Pad Layout . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34
10. 8-Pin PCB Land Pattern . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35
Document Change List . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .36
Contact Information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .37
Rev. 1.5
3
Si570/Si571
1. Detailed Block Diagrams
V
DD
GND
f
XTAL
+
RFREQ
M
DCO
f
osc
÷HS_DIV
÷N1
CLKOUT+
CLKOUT–
Frequency
Control
OE
SDA
SCL
Control
Interface
NVM
RAM
Figure 1. Si570 Detailed Block Diagram
V
DD
GND
f
XTAL
V
C
ADC
VCADC
+
RFREQ
M
DCO
f
osc
÷HS_DIV
÷N1
CLKOUT+
CLKOUT–
Frequency
Control
OE
SDA
SCL
Control
Interface
NVM
RAM
Figure 2. Si571 Detailed Block Diagram
4
Rev. 1.5
Si570/Si571
2. Electrical Specifications
Table 1. Recommended Operating Conditions
Parameter
Symbol
Test Condition
Min
Typ
Max
Unit
3.3 V option
Supply Voltage
1
V
DD
2.5 V option
1.8 V option
Output enabled
LVPECL
CML
LVDS
CMOS
TriState mode
Output Enable (OE)
2
,
Serial Data (SDA),
Serial Clock (SCL)
Operating Temperature Range
T
A
V
IH
V
IL
2.97
2.25
1.71
—
—
—
—
—
0.75 x V
DD
—
–40
3.3
2.5
1.8
120
108
99
90
60
—
—
—
3.63
2.75
1.89
130
117
108
98
75
—
0.5
85
V
ºC
V
Supply Current
I
DD
mA
Notes:
1.
Selectable parameter specified by part number. See Section "7. Ordering Information" on page 32 for further details.
2.
OE pin includes a 17 k pullup resistor to V
DD
. See “7.Ordering Information”.
Table 2. V
C
Control Voltage Input (Si571)
Parameter
Symbol
Test Condition
Min
Typ
Max
Unit
Control Voltage Tuning Slope
1,2,3
K
V
V
C
10 to 90% of V
DD
—
33
45
90
135
180
356
±1
±5
10.0
—
V
DD
/2
—
ppm/V
Control Voltage Linearity
4
Modulation Bandwidth
V
C
Input Impedance
Nominal Control Voltage
5
Control Voltage Tuning Range
L
VC
BW
Z
VC
V
CNOM
V
C
BSL
Incremental
–5
–10
9.3
500
+5
+10
10.7
—
—
V
DD
%
kHz
k
V
V
@ f
O
—
0
Notes:
1.
Positive slope; selectable option by part number. See "7. Ordering Information" on page 32.
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 is
determined with V
C
ranging from 10 to 90% of V
DD
.
5.
Nominal output frequency set by V
CNOM
= 1/2 x V
DD
.
Rev. 1.5
5
Switching Power Supply Study Group
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