SM802117
ClockWorks™ GbE (125MHz)
Ultra-Low Jitter, LVPECL
Frequency Synthesizer
General Description
The SM802117 is a member of the ClockWorks™ family of
devices from Micrel and provides an extremely low-noise
timing solution for GbE 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 LVPECL output clocks at 125MHz. There
are two differential clock outputs each with it’s own OE pin
allowing them to be disabled independently. The
SM802117 accepts a 25 MHz crystal or LVCMOS
reference clock.
Data sheets and support documentation can be found on
Micrel’s web site at:
www.micrel.com
.
HU
UH
Features
•
Generates one or two LVPECL clock outputs at 125MHz
•
2.5V or 3.3V operating range
•
Typical phase jitter @ 125MHz
(1.875MHz to 20MHz): 115fs
•
Industrial temperature range (–40°C to +85°C)
•
Green, RoHS, and PFOS compliant
•
Available in 24-pin 4mm
×
4mm QFN package
Applications
•
Gigabit Ethernet - PHY
___________________________________________________________________________________________________________
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
October 2011
M9999-101311-B
hbwhelp@micrel.com
or (408) 955-1690
Micrel, Inc.
SM802117
Ordering Information
Part Number
SM802117UMG
SM802117UMGTR
Note:
1. Devices are Green, RoHS, and PFOS compliant.
Marking
802117
802117
Shipping
Tube
Tape and Reel
Temperature Range
–40°C to +85°C
–40°C to +85°C
Package
24-Pin QFN
24-Pin QFN
Pin Configuration
24-Pin QFN
(Top View)
Pin Description
Pin Number
19, 20
22, 23
24
2
Pin Name
/Q1, Q1
/Q2, Q2
VDDO2
VSSO2
Pin Type
O, (DIF)
O, (DIF)
PWR
PWR
Pin Level
LVPECL
LVPECL
Pin Function
Differential Clock Output from Bank 1
125MHz
Differential Clock Output from Bank 2
125MHz
Power Supply for Output Bank 2
Power Supply Ground for Output Bank 2
PLL Bypass, Selects Output Source
3
PLL_BYPASS
I, (SE)
LVCMOS
0 = Normal PLL Operation
1 = Output from Input Reference Clock or Crystal
45KΩ pull-down
4
XTAL_SEL
I, (SE)
LVCMOS
Selects PLL Input Reference Source
0 = REF_IN, 1 = XTAL, 45KΩ pull-up
October 2011
2
M9999-101311-B
hbwhelp@micrel.com
or (408) 955-1690
Micrel, Inc.
SM802117
Pin Description (Continued)
Pin Number
5, 6 11, 16,18
1
13, 14, 15
17
21
8
9
10
7
12
Pin Name
TEST
VDD
VSS
VDDO1
VSSO1
REF_IN
XTAL_IN
XTAL_OUT
OE1
OE2
PWR
PWR
PWR
PWR
I, (SE)
I, (SE)
O, (SE)
I, (SE)
I, (SE)
LVCMOS
crystal
crystal
LVCMOS
LVCMOS
Pin Type
Pin Level
Pin Function
Factory Test pins, Do not connect anything to these pins.
Core Power Supply
Core Power Supply Ground
Power Supply for Output Bank 1
Power Supply Ground for Output Bank 1
Reference Clock Input
Crystal Reference Input, no load caps needed.
See Fig. 5.
Crystal Reference Output, no load caps needed.
See Fig. 5.
Output Enable, Q1 disables to tri-state,
0 = Disabled, 1 = Enabled, 45KΩ pull-up
Output Enable, Q2 disables to tri-state,
0 = Disabled, 1 = Enabled, 45KΩ pull-up
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
.
HU
UH
Truth Table
PLL_BYPASS
0
1
−
−
XTAL_SEL
−
−
0
1
INPUT
−
−
REF_IN
XTAL
OUTPUT
PLL
XTAL/REF_IN
−
−
October 2011
3
M9999-101311-B
hbwhelp@micrel.com
or (408) 955-1690
Micrel, Inc.
SM802117
Absolute Maximum Ratings
(1)
Supply Voltage (V
DD
, V
DDO1/2
) ......................................+4.6V
Input Voltage (V
IN
). ............................. –0.50V to V
DD
+ 0.5V
Lead Temperature (soldering, 20sec.)....................... 260°C
Case Temperature ..................................................... 115°C
Storage Temperature (T
s
) .........................–65°C to +150°C
Operating Ratings
(2)
Supply Voltage (V
DD
, V
DDO1/2
)............... +2.375V to +3.465V
Ambient Temperature (T
A
) .......................... –40°C to +85°C
Junction Thermal Resistance
(3)
QFN (θ
JA
)
Still-Air.........................................................50°C/W
QFN (ψ
JB
)
Junction-to-Board .......................................30°C/W
DC Electrical Characteristics
(4)
V
DD
= V
DDO1/2
= 3.3V
±5%
or 2.5V
±5%
V
DD
= 3.3V
±5%,
V
DDO1/2
= 2.5V
±5%
T
A
=
−40°C
to
+85°C.
Symbol
V
DD
, V
DDO1/2
V
DD
, V
DDO1/2
I
DD
REF_IN
I
DD
XTAL
Parameter
2.5V Operating Voltage
3.3V Operating Voltage
Supply current V
DD
+ V
DDO
XTAL_SEL = 0
Outputs open
Supply current V
DD
+ V
DDO
XTAL_SEL = 1
Outputs open
125MHz - 1 output
125MHz - 2 outputs
125MHz - 1 output
125MHz - 2 outputs
Condition
Min.
2.375
3.135
Typ.
2.5
3.3
97
114
87
104
Max.
2.625
3.465
125
148
113
135
Units
V
V
mA
mA
mA
mA
LVPECL OUTPUT DC Electrical Characteristics
(4)
V
DD
= V
DDO1/2
= 3.3V
±5%
or 2.5V
±5%
V
DD
= 3.3V
±5%,
V
DDO1/2
= 2.5V
±5%
T
A
=
−40°C
to
+85°C.
R
L
= 50Ω to V
DDO
−
2V
Symbol
V
OH
V
OL
V
SWING
Note:
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.
The data sheet limits are not guaranteed if the device is operated beyond the operating ratings.
Package thermal resistance assumes exposed pad is soldered (or equivalent) to the devices most negative potential on the PCB.
The circuit is designed to meet the AC and DC specifications shown in the above table(s) after thermal equilibrium has been established.
Parameter
Output High Voltage
Output Low Voltage
Output Voltage Swing
Condition
Min.
V
DDO
– 1.145
V
DDO
– 1.945
0.6
Typ.
V
DDO
– 0.97
V
DDO
– 1.77
0.8
Max.
V
DDO
– 0.845
V
DDO
– 1.645
1.0
Units
V
V
V
2.
3.
4.
October 2011
4
M9999-101311-B
hbwhelp@micrel.com
or (408) 955-1690
Micrel, Inc.
SM802117
LVCMOS (PLL_BYPASS, XTAL_SEL, OE1/2) DC Electrical Characteristics
(4)
V
DD
= 3.3V
±5%,
or 2.5V
±5%,
T
A
=
−40°C
to
+85°C.
Symbol
V
IH
V
IN
I
IH
I
IL
Parameter
Input High Voltage
Input Low Voltage
Input High Current
Input Low Current
V
DD
= V
IN
= 3.465V
V
DD
= 3.465V, V
IN
= 0V
−150
Condition
Min.
2
−0.3
Typ.
Max.
V
DD
+ 0.3
0.8
150
Units
V
V
μA
μA
REF_IN DC Electrical Characteristics
(4)
V
DD
= 3.3V
±5%,
or 2.5V
±5%,
T
A
=
−40°C
to
+85°C.
Symbol
V
IH
V
IL
I
IN
Parameter
Input High Voltage
Input Low Voltage
Input Current
XTAL_SEL = V
IL
, V
IN
= 0V to V
DD
XTAL_SEL = V
IH
, V
IN
= V
DD
Condition
Min.
1.1
−0.3
−5
20
Typ.
Max.
V
DD
+ 0.3
0.6
5
Units
V
V
μA
µA
Crystal Characteristics
Parameter
Mode of Oscillation
Frequency
Equivalent Series Resistance (ESR)
Shunt Capacitor, C0
Correlation Drive Level
Condition
10 to 12pF Load
Min.
Typ.
Max.
Units
MHz
Ω
pF
uW
Fundamental, Parallel Resonant
25
50
1
5
10
100
October 2011
5
M9999-101311-B
hbwhelp@micrel.com
or (408) 955-1690
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