SM802121 [MICREL]
ClockWorks10GbE (156.25MHz), Ultra-Low Jitter, LVPECL Frequency Synthesizer; ClockWorks10GbE （ 156.25MHz ） ，超低抖动LVPECL频率合成器
| 型号： | SM802121 |
| 厂家： | 
MICREL SEMICONDUCTOR |
| 描述： | ClockWorks10GbE (156.25MHz), Ultra-Low Jitter, LVPECL Frequency Synthesizer |
| 文件： | 总10页 (文件大小：301K) |
| 中文： | 中文翻译 | 下载： | 下载PDF数据表文档文件 |
SM802121
ClockWorks 10GbE
(156.25MHz), Ultra-Low Jitter, LVPECL
Frequency Synthesizer
General Description
Features
The SM802121 is a member of the ClockWorks family of
devices from Micrel and provides an extremely low-noise
timing solution for 10GbE Ethernet clock signals. It is
based upon a unique patented RotaryWave® architecture
that provides very-low phase noise.
Generates one LVPECL clock outputs at 156.25MHz
2.5V or 3.3V operating range
Typical phase jitter @ 156.25MHz
(1.875MHz to 20MHz): 110fs
Industrial temperature range
Green, RoHS-, and PFOS- compliant
Available in 24-pin 4mm 4mm QFN package
The device operates from a 2.5V or 3.3V power supply
and synthesizes an LVPECL output clock at 156.25MHz.
The SM802121 accepts a 25MHz crystal or LVCMOS
reference clock.
Data sheets and support documentation can be found on
Micrel’s web site at: www.micrel.com.
Applications
10 Gigabit Ethernet
Block Diagram
ClockWorks is a trademark of Micrel, Inc
RotaryWave is a registered trademark of Multigig, Inc.
Micrel Inc. • 2180 Fortune Drive • San Jose, CA 95131 • USA • tel +1 (408) 944-0800 • fax + 1 (408) 474-1000 • http://www.micrel.com
M9999-011212-A
January 2012
hbwhelp@micrel.com or (408) 955-1690
Micrel, Inc.
SM802121
Ordering Information(1)
Part Number
Marking
802121
802121
Shipping
Tube
Temperature Range
40C to +85C
Package
SM802121UMG
SM802121UMGTR
24-Pin QFN
24-Pin QFN
Tape and Reel
40C to +85C
Note:
1. Devices are Green, RoHS-, and PFOS- compliant.
Pin Configuration
24-Pin QFN
(Top View)
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SM802121
Pin Description
Pin Number
16, 17
Pin Name
Pin Type
O, (DIF)
PWR
Pin Level
Pin Function
/Q, Q
VDDO
VSSO
LVPECL
Differential Clock Output 156.25MHz.
Power Supply for Output.
Power Supply Ground for Output.
1, 18
2, 22
PWR
Selects PLL Input Reference Source (0 = REF_IN, 1 =
XTAL, 45KΩ pull-up).
6
XTAL_SEL
I, (SE)
LVCMOS
3, 4, 20, 21,
23, 24
NC
No Connect. Do not connect anything to these pins.
5, 7, 12, 15, 19
8
TEST
Factory Test Pins. Do not connect anything to these pins.
Core Power Supply.
VDD
VSS
PWR
PWR
Core Power Supply Ground. The exposed pad must be
connected to the VSS ground plane.
13, 14
(Exposed Pad)
9
REF_IN
XIN
I, (SE)
I, (SE)
O, (SE)
LVCMOS
crystal
Reference Clock Input.
10
11
Crystal Reference Input. No load caps needed. (See Fig. 5)
Crystal Reference Output. No load caps needed. (See Fig. 5)
XOUT
crystal
Application Information
Input Reference
When operating with a crystal input reference, do not
apply a switching signal to REF_IN.
Crystal load capacitance is built inside the die so no
external capacitance is needed. See the Selecting a
quartz crystal for the Clockworks Flex I Family of
Precision Synthesizers application note for further
details.
Contact Micrel’s HBW applications group if you need
assistance on selecting a suitable crystal for your
application at hbwhelp@micrel.com
Crystal Layout
Keep the layers under the crystal as open as possible
and do not place switching signals or noisy supplies
under the crystal.
Truth Table
XTAL_SEL
INPUT
REF_IN
XTAL
0
1
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SM802121
Absolute Maximum Ratings(1)
Operating Ratings(2)
Supply Voltage (VDD, VDDO) .........................................+4.6V
Input Voltage (VIN)...............................0.50V to VDD + 0.5V
Lead Temperature (soldering, 20s)............................ 260°C
Case Temperature ..................................................... 115°C
Storage Temperature (Ts) ......................... 65C to 150°C
Supply Voltage (VDD, VDDO).................. +2.375V to +3.465V
Ambient Temperature (TA).......................... 40°C to +85°C
Junction Thermal Resistance(3)
QFN (JA)
Still-Air.........................................................50°C/W
QFN (JB)
Junction-to-Board ....................................... 30°C/W
DC Electrical Characteristics(4)
VDD = VDDO = 3.3V 5% or 2.5V 5%
VDD = 3.3V 5%, VDDO= 3.3V 5% or 2.5V 5%
TA = 40C to 85C.
Symbol
Parameter
Condition
Min.
2.375
3.135
Typ.
2.5
Max.
2.625
3.465
Units
VDD, VDDO
VDD, VDDO
2.5V Operating Voltage
3.3V Operating Voltage
V
V
3.3
IDD
Supply Current VDD + VDDO
Supply Current VDD + VDDO
XTAL_SEL = 0; REF_IN source, outputs open
XTAL_SEL = 1; CRYSTAL source, outputs open
78
88
100
114
mA
mA
IDD
LVPECL DC Electrical Characteristics(4)
VDD = VDDO= 3.3V 5% or 2.5V 5%
VDD = 3.3V 5%, VDDO = 3.3V 5% or 2.5V 5%
TA = 40C to 85C. RL = 50ꢀ to VDDO 2V
Symbol
VOH
Parameter
Condition
Min.
VDDO 1.145
VDDO 1.945
0.6
Typ.
Max.
Units
Output High Voltage
Output Low Voltage
Output Voltage Swing
V
V
V
VDDO 0.97 VDDO 0.845
VDDO 1.77 VDDO 1.645
VOL
VSWING
0.8
1.0
Notes:
1. Permanent device damage may occur if absolute maximum ratings are exceeded. This is a stress rating only and functional operation is not implied
at conditions other than those detailed in the operational sections of this data sheet. Exposure to absolute maximum rating conditions for extended
periods may affect device reliability.
2. The data sheet limits are not guaranteed if the device is operated beyond the operating ratings.
3. Package thermal resistance assumes exposed pad is soldered (or equivalent) to the devices most negative potential on the PCB.
4. The circuit is designed to meet the AC and DC specifications shown in the above table(s) after thermal equilibrium has been established.
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Micrel, Inc.
SM802121
LVCMOS (XTAL_SEL) DC Electrical Characteristics(4)
VDD = 3.3V 5%, or 2.5V 5%, TA = 40C to 85C.
Symbol
VIH
Parameter
Condition
Min.
2
Typ.
Max.
VDD + 0.3
0.8
Units
V
Input High Voltage
Input Low Voltage
VIL
V
0.3
IIH
IIL
Input High Current
Input Low Current
VDD = VIN = 3.465V
5
A
A
VDD = 3.465V, VIN = 0V
150
REF_IN DC Electrical Characteristics(4)
VDD = 3.3V 5%, or 2.5V 5%, TA = 40C to 85C.
Symbol
VIH
Parameter
Condition
Min.
1.1
Typ.
20
Max.
VDD + 0.3
0.6
Units
V
Input High Voltage
Input Low Voltage
VIL
V
0.3
5
XTAL_SEL = VIL, VIN = 0V to VDD
XTAL_SEL = VIH, VIN = VDD
5
A
µA
IIN
Input Current
Crystal Characteristics
Parameter
Condition
Min.
Typ.
Max.
Units
Mode of Oscillation
Frequency
10pF Load
Fundamental, Parallel Resonant
25
MHz
ꢀ
Equivalent Series Resistance (ESR)
Shunt Capacitor (C0)
Correlation Drive Level
50
1
5
pF
10
100
uW
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Micrel, Inc.
SM802121
AC Electrical Characteristics(4, 5)
VDD = VDDO = 3.3V 5% or 2.5V 5%
VDD = 3.3V 5%, VDDO= 3.3V 5% or 2.5V 5%
TA = 40C to 85C. RL = 50ꢀ to VDDO 2V
Symbol
FOUT
Parameter
Output Frequency
Condition
Min.
Typ.
156.25
25
Max.
Units
MHz
MHz
ps
FREF
Reference Input Frequency
LVPECL Output Rise/Fall Time
Output Duty Cycle
TR/TF
ODC
80
48
175
350
52
20% 80%
50
%
TLOCK
PLL Lock Time
20
ms
156.25MHz
110
250
RMS Phase Jitter(6)
Integration Range (1.875MHz 20MHz)
Integration Range (12kHz 20MHz)
6.25MHz
fs
Tjit()
Spurious Noise Components
dBc
75
Notes:
5. All phase-noise measurements were taken with an Agilent 5052B phase-noise system.
6. Measured using a 25MHz crystal as the input reference source. If using an external reference input, use a low phase noise source. With an
external reference, the phase noise will follow the input source phase noise up to about 1MHz offset.
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Micrel, Inc.
SM802121
Phase Noise Plots (XTAL Source)
Phase Noise Plot: 156.25MHz, 1.875MHz 20MHz 101fS
Phase Noise Plot: 156.25MHz, 12kHz 20MHz 243fS
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SM802121
Figure 1. Duty Cycle Timing
Figure 2. All Outputs Rise/Fall Time
Figure 3. RMS Phase/Noise Jitter
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SM802121
Figure 4. LVPECL Output Load and Test Circuit
Figure 5. Crystal Input Interface
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Micrel, Inc.
SM802121
Package Information
24-Pin Package Type
MICREL, INC. 2180 FORTUNE DRIVE SAN JOSE, CA 95131 USA
TEL +1 (408) 944-0800 FAX +1 (408) 474-1000 WEB http://www.micrel.com
Micrel makes no representations or warranties with respect to the accuracy or completeness of the information furnished in this data sheet. This
information is not intended as a warranty and Micrel does not assume responsibility for its use. Micrel reserves the right to change circuitry,
specifications and descriptions at any time without notice. No license, whether express, implied, arising by estoppel or otherwise, to any intellectual
property rights is granted by this document. Except as provided in Micrel’s terms and conditions of sale for such products, Micrel assumes no liability
whatsoever, and Micrel disclaims any express or implied warranty relating to the sale and/or use of Micrel products including liability or warranties
relating to fitness for a particular purpose, merchantability, or infringement of any patent, copyright or other intellectual property right.
Micrel Products are not designed or authorized for use as components in life support appliances, devices or systems where malfunction of a product
can reasonably be expected to result in personal injury. Life support devices or systems are devices or systems that (a) are intended for surgical implant
into the body or (b) support or sustain life, and whose failure to perform can be reasonably expected to result in a significant injury to the user. A
Purchaser’s use or sale of Micrel Products for use in life support appliances, devices or systems is a Purchaser’s own risk and Purchaser agrees to fully
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© 2012 Micrel, Incorporated.
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