SM802128
ClockWorksΤΜ 10GbE Octal 156.25MHz,
312.5MHz, Ultra-Low Jitter, LVPECL
Frequency Synthesizer
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
January 2012 hbwhelp@micrel.com or (408) 955-1690
General Description
The SM802128 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.
The device operates from a 3.3V or 2.5V power supply
and synthesizes eight LVPECL output clocks at
156.25MHz or 312.5MHz. The SM802128 accepts a 25
MHz crystal or LVCMOS reference clock.
Data sheet and support documentation can be found on
Micrel’s web site at: www.micrel.com.
Features
• Generates eight LVPECL clocks at 156.25MHz or
312.5MHz
• 2.5V or 3.3V operating range
• Typical phase jitter @ 156.25MHz
(1.875MHz to 20MHz): 110fs with crystal reference
• Industrial temperature range (–40°C to +85°C)
• Green, RoHS, and PFOS compliant
• Available in 44-pin 7mm × 7mm QFN package
________________________________________________________________________________________________________
Block Diagram
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Ordering Information (1)
Part Number Marking Shipping Temperature Range Package
SM802128UMG 802128 Tray –40°C to +85°C 44-Pin QFN
SM802128UMGTR 802128 Tape and Reel –40°C to +85°C 44-Pin QFN
Note:
1. Devices are Green, RoHS, and PFOS compliant.
Pin Configuration
44-Pin QFN
(Top View)
Pin Description
Pin Number Pin Name Pin Type Pin Level Pin Function
25, 26
28, 29
32, 33
35, 36
/Q1, Q1
/Q2, Q2
/Q3, Q3
/Q4, Q4
O, (DIF) LVPECL Differential Clock Outputs from Bank 1 (156.25MHz or
312.5MHz).
41, 42
1, 2
4, 5
7, 8
/Q5, Q5
/Q6, Q6
/Q7, Q7
/Q8, Q8
O, (DIF) LVPECL Differential Clock Outputs from Bank 2 (156.25MHz or
312.5MHz).
31, 37, 38 VDDO1 PWR Power Supply for the Outputs on Bank 1.
43, 44, 16 VDDO2 PWR Power Supply for the Outputs on Bank 2.
24, 39 VSSO1 PWR Power Supply Ground for the Outputs on Bank 1.
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Pin Description (continue d)
Pin Number Pin Name Pin Type Pin Level Pin Function
3, 6, 40 VSSO2 PWR Power Supply Ground for the Outputs on Bank 2
11, 20, 27, 30,
34 TEST Factory Test Pins. Do not connect anything to these pins.
12, 13 VDD PWR Core Power Supply
21, 23
VSS
(Exposed
Pad)
PWR
Core Power Supply Ground. The exposed pad must be
connected to the VSS ground plane.
17 REF_IN I, (SE) LVCMOS Reference Clock Input
18 XTAL_IN I, (SE) Crystal Crystal Reference Input, no load caps needed (See Figure 5).
19 XTAL_OUT O, (SE) Crystal
Crystal Reference Output, no load caps needed (See Figure
5).
15 OE1 I, (SE) LVCMOS
Output Enable, Q1-Q4 disables to tri-state, 0 = Disabled, 1 =
Enabled, 45K Pull-Up.
22 OE2 I, (SE) LVCMOS
Output Enable, Q5-Q8 disables to tri-state, 0 = Disabled, 1 =
Enabled, 45K Pull-Up.
9 PLL_BYPASS I, (SE) LVCMOS
PLL Bypass, Selects Output Source
0 = Normal PLL Operation
1 = Output from Input Reference Clock or Crystal
45K Pull-Down
10 XTAL_SEL I, (SE) LVCMOS
Selects PLL Input Reference Source
0 = REF_IN, 1 = XTAL, 45K Pull-Up
14 FSEL I, (SE) LVCMOS
Frequency Select, 1 = 156.25MHz, 0 = 312.5MHz,
45K Pull-Up
Truth Tables
OE1/2
0 Tri-state
1 LVPECL
FSEL Output Frequency (MHz)
0 312.5
1 156.25
PLL_BYPASS/CSB XTAL_SEL
0 −
−
PLL
1 −
−
XTAL/REF_IN
− 0 REF_IN
−
− 1 XTAL
−
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Absolute Maximum Ratings (1)
Supply Voltage (VDD, VDDO1/2) ……....................+4.6V
Input Voltage (VIN)……….…….…-0.50V to VDD+0.5V
Lead Temperature (soldering, 20sec.)…………260°C
Case Temperature……………………………….115°C
Storage Temperature (Ts)…………...-65°C to +150°C
Operating Ratings (2)
Supply Voltage (VDD, VDDO1/2) ............... +2.375V to +3.465V
Ambient Temperature (TA) .......................... –40°C to +85°C
Junction Thermal Resistance(3)
QFN (θ JA)
Still-Air ............................................................... 24°C/W
QFN (ψ JB)
Junction-to-Board ................................................ 8°C/W
DC Electrical Characteristics (4)
VDD = VDDO1/2 = 3.3V ±5% or 2.5V ±5%
VDD = 3.3V ±5%, VDDO1/2 = 3.3V ±5% or 2.5V ±5%
TA = -40°C to +85°C.
Symbol Parameter Condition Min. Typ. Max. Units
VDD, VDDO1/2 2.5V Operating Voltage VDDO1=VDDO2 2.375 2.5 2.625 V
VDD, VDDO1/2 3.3V Operating Voltage VDDO1=VDDO2 3.135 3.3 3.465 V
IDD
Supply current VDD + VDDO
Outputs open
156.25MHz 220 275
mA
312.5MHz 275 345
LVPECL DC Electrical Char acteristics (4)
VDD = VDDO1/2 = 3.3V ±5% or 2.5V ±5%
VDD = 3.3V ±5%, VDDO1/2 = 3.3V ±5% or 2.5V ±5%
TA = −40°C to +85°C. RL = 50 to VDDO-2V
Symbol Parameter Condition Min. Typ. Max. Units
VOH Output High Voltage VDDO – 1.145 VDDO – 0.97 VDDO – 0.845 V
VOL Output Low Voltage VDDO – 1.945 VDDO – 1.77 VDDO – 1.645 V
VSWING Output Voltage Swing 0.6 0.8 1.0 V
LVCMOS (PLL_BYPA SS, X T AL_SEL, OE1, OE2, FSEL) DC Electrical Characteristics (4)
VDD = 3.3V ±5%, or 2.5V ±5%, TA = −40°C to +85°C.
Symbol Parameter Condition Min. Typ. Max. Units
VIH Input High Voltage 2 VDD + 0.3 V
VIL Input Low Voltage −0.3 0.8 V
IIH Input High Current VDD = VIN = 3.465V 150
μA
IIL Input Low Current VDD = 3.465V, VIN = 0V −150
μA
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REF_IN DC Electrical Characteristics(4)
VDD = 3.3V ±5%, or 2.5V ±5%, TA = -40°C to +85°C.
Symbol Parameter Condition Min. Typ. Max. Units
VIH Input High Voltage 1.1 VDD + 0.3 V
VIL Input Low Voltage −0.3 0.6 V
IIN Input Current
XTAL_SEL = VIL, VIN = 0V to VDD −5 5
μA
XTAL_SEL = VIH, VIN = VDD 20 µA
Crystal Characteristics
Paramete
r
Condition Min. Typ. Max. Units
Mode of Oscillation 10pF Load Fundamental, Parallel Resonant
Frequency 25 MHz
Equivalent Series Resistance (ESR) 50
Shunt Capacitor, C0 1 5 pF
Correlation Drive Level 10 100 uW
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AC Electrical Characteristics(4, 5)
VDD = VDDO1/2 = 3.3V ±5% or 2.5V ±5%
VDD = 3.3V ±5%, VDDO1/2 = 3.3V ±5% or 2.5V ±5%
TA = −40°C to +85°C. RL = 50 to VDDO − 2V
Symbol Parameter Condition Min Typ Max Units
FOUT1 Output Frequency 1 FSEL = 1 156.25 MHz
FOUT2 Output Frequency 2 FSEL = 0 312.5 MHz
FREF Reference Input Frequency 25 MHz
TR/TF
ODC
LVPECL Output Rise/Fall Time
Output Duty Cycle
20% – 80% 80 175 350 ps
48 50 52 %
TSKEW Output-to-Output Skew Q1 – Q8
(6
)
45 ps
TLOCK PLL Lock Time 20 ms
Tjit(∅) RMS Phase Jitter(7)
156.25MHz
Integration Range (1.875MHz – 20MHz)
Integration Range (12kHz – 20MHz)
312.5MHz
Integration Range (1.875MHz – 20MHz)
Integration Range (12kHz – 20MHz)
110
250
110
250
fs
Spurious Noise Components 6.25MHz using 156.25MHz
12.5MHz using 312.5MHz -80
-85 dBc
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 after thermal equilibrium has been established.
5. All phase−noise measurements were taken with an Agilent 5052B phase−noise system.
6. Defined as skew between outputs at the same supply voltage and with equal load conditions and same frequency; measured at the output
differential crossing points.
7. 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 frequency.
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Application Information
Input Reference
When operating with a crystal input reference, do not
apply a switching signal to REF_IN.
Crystal Layout
Keep the layers under the crystal as open as possible
and do not place switching signals or noisy supplies
under the crystal.
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.
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Phase Noise Plots
Phase Noise Plot: 156.25MHz, 1.875MHz − 20MHz 108fs
Phase Noise Plot: 156.25MHz, 12kHz − 20MHz 244fs
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Phase Noise Plots (Continued)
Phase Noise Plot: 312.5MHz, 1.875MHz − 20MHz 113fs
Phase Noise Plot: 312.5MHz, 12kHz − 20MHz 248fs
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Figure 1. Duty Cycle Timing Figure 2. All Outputs Rise/Fall Time
Figure 3. RMS Phase/Noise/Jitter
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Figure 4. LVPECL Output Load Figure 5. Crystal Input Interface
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Package Information
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
indemnify Micrel for any damages resulting from such use or sale.
© 2012 Micrel, Incorporated.
