SM840051KA [MICREL]
10 Gigabit Ethernet Ultra-Low Jitter Clock Synthesizer; 万兆以太网超低抖动时钟合成器
| 型号： | SM840051KA |
| 厂家： | 
MICREL SEMICONDUCTOR |
| 描述： | 10 Gigabit Ethernet Ultra-Low Jitter Clock Synthesizer |
| 文件： | 总10页 (文件大小：292K) |
| 中文： | 中文翻译 | 下载： | 下载PDF数据表文档文件 |
SM840051
10 Gigabit Ethernet Ultra-Low Jitter Clock
Synthesizer
General Description
Features
The SM840051 clock synthesizer was designed for
Ethernet standards. The SM840051 is optimized for 77.76,
78.125, 80.56, 155.52, 156.25, and 161.13MHz, using a
crystal at 1/8th the output frequency. The SM840051
includes a unique power reduction methodology, along
with a patented RotaryWave™ architecture, that provides
a stable clock with very low noise for optimized
performance. This yields an overall improved Bit Error
Rate (BER) and improved waveform integrity.
• Generates a single LVCMOS/LVTTL output
• Output Frequencies: 77.76, 78.125, 80.56, 155.52,
156.25, and 161.13MHz
• RMS Phase Jitter at 156.25MHz( 1.875MHz-20MHz):
58fs (typical)
• Integrated loop filter components
• Operates with either a 3.3V or 2.5V supply
• Power consumption is <77mA @ 3.3 V
• Fundamental parallel resonant crystal
Power supplies of either 3.3V or 2.5V are supported, with
superior jitter and phase noise performance. An FSEL pin
supports 4x or 8x multiplication of the crystal frequency.
• Crystal Frequencies: 20.141601MHz,19.53125MHz, and
19.44MHz
The SM840051 provides ultra-low jitter, and consumes low
power.
• Industrial temperature range: –40°C to +75°C
• Available in 8-pin TSSOP package
Datasheets and support documentation can be found on
Micrel’s web site at: www.micrel.com.
Applications
• 10 Gigabit Ethernet
• SONET/SDH
____________________________________________________________________________
Block Diagram
RotaryWave is a 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
M9999-050710-C
hbwhelp@micrel.com or (408) 955-1690
May 2010
Micrel, Inc.
SM840051
Ordering Information(1)
Part Number
Package
Type
Operating Range
Package Marking
Lead
Finish
SM840051KA
SM840051KA TR(2)
Note:
K-8
K-8
-40°C to +75°C
-40°C to +75°C
840051
840051
NiPdAu
NiPdAu
1. Devices are Green, RoHS-compliant and PFOS-compliant.
2. Tape and Reel.
Pin Configuration
8-Pin TSSOP (K-8)
Pin Description
Pin Number
Pin Name
VDDA
OE
Type
Level
Pin Function
1
2
3
4
5
6
7
8
P
I
Analog power.
Pull-up
Output Enable: 1 = Enable, 0 = Disable.
Crystal Output.
XTAL OUT
XTAL IN
FSEL
O
I
Crystal Input.
I
Pull down
Frequency Select Pin.
Ground.
GND
P
O
P
Q0
Single Ended LVCMOS Clock Out.
Core Power.
VDD
Configuring the SM840051 (Frequency Table)
Xtal Frequency (MHz)
20.141601
20.141601
19.53125
FSEL
Output Frequency (MHz)
161.132812
80.566406
156.25
0
1
0
1
0
1
19.53125
78.125
19.44
155.52
19.44
77.76
Output Enable
OE
0
Output
Disable
Enable
1
M9999-050710-C
hbwhelp@micrel.com or (408) 955-1690
May 2010
2
Micrel, Inc.
SM840051
Absolute Maximum Ratings(1)
Operating Ratings(2)
Supply Voltage (VDD)...................................................+4.6V
Input Voltage (VIN)................................ –0.50V to VDD+0.5V
Output Voltage (VOUT) .......................... –0.50V to VDD+0.5V
Lead Temperature (soldering, 20sec.)....................... 260°C
Storage Temperature (Ts) .........................–65°C to +150°C
Supply Voltage (VIN)............................. +2.375V to +3.465V
Ambient Temperature (TA) ..........................–40°C to +75°C
Junction Thermal Resistance
TSSOP (θJA).....................................................150°C/W
DC Electrical Characteristics
VDD = 2.5V ±5%; TA = –40°C to +75°C, unless noted.
Symbol
Parameter
Condition
Min
Typ
2.50
2.50
12
Max
2.625
2.625
20
Units
V
VDD
VDDA
IDD
Core Supply Voltage
Analog Supply Voltage
Core Supply Current
Analog Supply Current
2.375
2.375
V
No load
mA
mA
IDDA
48
55
DC Electrical Characteristics
VDD = 3.3V ±5%; TA = –40°C to +75°C, unless noted.
Symbol
VDD
Parameter
Condition
Min
Typ
3.30
3.30
15
Max
3.465
3.465
25
Units
V
Core Supply Voltage
Analog Supply Voltage
Core Supply Current
Analog Supply Current
3.135
3.135
VDDA
IDD
V
No load
mA
mA
IDDA
49
60
LVCMOS Electrical Characteristics
VDD = 2.5V and 3.3V ±5%; TA = –40°C to +75°C, unless noted.
Symbol
Parameter
Condition
Min
2
Typ
Max
VDD +0.3
VDD + 0.3
0.80
Units
V
VDD = 3.3V ±5%
VIH
Input HIGH Voltage
V
DD = 2.5V ±5%
VDD = 3.3V ±5%
DD = 2.5V ±5%
VDD = 3.3V ±5%
DD = 2.5V ±5%
1.7
V
-0.30
-0.30
2.6
V
VIL
Input LOW Voltage
V
0.70
V
V
VOH
Output HIGH Voltage
V
1.8
V
VOL
IIH
Output LOW Voltage
Input HIGH Current
Input LOW Current
Input HIGH Current
Input LOW Current
0.5
5
V
Output Enable input
Output Enable input
FSEL input
µA
µA
µA
µA
IIL
-150
-5
IIH
150
IIL
FSEL input
Notes:
1. Exceeding the absolute maximum rating may damage the device.
2. The device is not guaranteed to function outside its operating rating.
M9999-050710-C
hbwhelp@micrel.com or (408) 955-1690
May 2010
3
Micrel, Inc.
SM840051
AC Electrical Characteristics
VDD = 2.5V and 3.3V ±5%; TA = –40°C to +75°C, unless noted.
Symbol
FOUT
Parameter
Condition
Min
Typ
58
Max
Units
MHz
fs
Output frequency
77.76
162.4
tJITTER
tR / tF
RMS phase jitter @ 156.25MHz Integration Range: 1.875M to 20MHz
Output rise/fall time
Output Duty Cycle
20% to 80%
100
48
350
52
ps
ODC
50
%
Test Circuit
3.3V Carrier Frequency, 156.25MHz
Offset from Carrier
100Hz
Measured Phase Noise
Unit
-85
dBc/Hz
dBc/Hz
dBc/Hz
dBc/Hz
dBc/Hz
dBc/Hz
dBc/Hz
1kHz
-122
-130
-127
-140
-165
-166
10kHz
100kHz
1MHz
10MHz
40MHz
Crystal Characteristics(1)
Parameter
Min
Typ
Max
Units
Mode of Oscillation
Frequency
Fundamental Parallel Resonant
19.44
20.3
50
7
MHz
Ω
Equivalent Series Resistance (ESR)
Shunt Capacitor
Drive Level
pF
1
mW
Note:
1. Devices are Green, RoHS-compliant and PFOS-compliant
M9999-050710-C
hbwhelp@micrel.com or (408) 955-1690
May 2010
4
Micrel, Inc.
SM840051
providing high resolution and easy integer divide ratios.
Output Divider ratios are fixed at either ÷20 or ÷40
controlled via the FSEL pin, and the feedback divider also
fixed at ÷160. Duty Cycle is inherently improved and
guarantees tight control and stability on this critical
specification. This provides improved specifications for
Duty Cycle, Jitter, Phase Noise, Power Consumption, and
noise sensitivity. Additionally, the SM840051 will operate
at either 3.3V or 2.5V supplies.
Functional Description
The SM840051 synthesizer provides a high performance
solution to frequency generation. Low cost crystals of
20.141601MHz, 19.53125MHz, and 19.44MHz are used to
provide low jitter output clocks of 161.132MHz, 156.25MHz
, and 155.52MHz, respectively. A single LVCMOS output,
capable of driving a 50 ohm load, is provided, which may
be tri-stated by the OE input.
The design of the SM840051 consumes very low power in
the PLL due to a patented technology in the VCO and the
associated dividers. The VCO range is ~3.2GHz to 3.5GHz
RMS Phase Noise/Jitter
Phase Noise Plot: 156.25MHz @ 3.3V
RMS Phase Jitter (Random)
1.875MHz to 20MHz = 58 fs (typical)
Noise Power
dBc/Hz
(Random)
1.875MHz to
20MHz
Offset Frequency ( Hz)
M9999-050710-C
hbwhelp@micrel.com or (408) 955-1690
May 2010
5
Micrel, Inc.
SM840051
Switching Waveforms
M9999-050710-C
hbwhelp@micrel.com or (408) 955-1690
May 2010
6
Micrel, Inc.
SM840051
Power Supply Filtering
Crystal Loading
The SM840051 provides separate power supply pins to
isolate any high switching noise from outputs to internal
core blocks. VDD and VDDA should be individually
connected to the power plane through vias. Bypass
capacitors should be used for each pin. Figure 2,
illustrates how the power supply filter for 3.3V and 2.5V is
configured.
Crystal Recommendations
This device requires
a
parallel resonance crystal.
Substituting a series resonance crystal will cause this
device to operate at the wrong frequency and violate the
ppm specifications.
To achieve low ppm error, the total capacitance the crystal
will see must be considered to calculate the appropriate
capacitive loading (CL).
Load Capacitance at each side: Trim Capacitance = Ct =
(2*CL-(Cb + Cd))
CL: Crystal load capacitance. Defined by manufacturer
Ct: External trim capacitors. (Trimmed CL Load
capacitance to get the right ppm)
Cb: Board capacitance (vias, traces, etc.)
Cd: Internal capacitance of the device (lead frame, bond
wires, pin, etc.)
Equivalent Series
Resistance (ESR)
Max.
Cut
Load
Cap.
Shunt
Cap.
Max.
Drive
Max.
Figure 2. Power Supply Filter
50Ω
AT
18pF
7pF
0.1mW
Crystal Input Interface
M9999-050710-C
hbwhelp@micrel.com or (408) 955-1690
May 2010
7
Micrel, Inc.
SM840051
Total capacitance seen by crystal = CL =
1
Example:
CL = 18pF, Cb = 2pF, Cd = 4pF
Trim Cap = Ct = 2 (18pF) - (2pF +4pF) = 30pF
The SM840051 has been characterized with 19.44MHz,
18pF parallel resonant crystal. The trim capacitors Ct1 and
Ct2 were optimized to minimize the ppm error.
1
+
1
(Ct1 + Cb1 + Cd1)
(Ct2 + Cb2 + Cd2)
To minimize the board capacitance, a short trace from pin
to crystal footprint without vias is desirable. It is preferable
to have ground shielding or distance between the crystal
traces and noisy signals on the board.
M9999-050710-C
hbwhelp@micrel.com or (408) 955-1690
May 2010
8
Micrel, Inc.
SM840051
Board Layout
M9999-050710-C
hbwhelp@micrel.com or (408) 955-1690
May 2010
9
Micrel, Inc.
SM840051
Package Information
8-Pin TSSOP (K-8)
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
The information furnished by Micrel in this data sheet is believed to be accurate and reliable. However, no responsibility is assumed by Micrel for its
use. Micrel reserves the right to change circuitry and specifications at any time without notification to the customer.
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.
© 2010 Micrel, Incorporated.
M9999-050710-C
hbwhelp@micrel.com or (408) 955-1690
May 2010
10
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