SM840051
10 Gigabit Ethernet Ultra-Low Jitter Clock
Synthesizer
General Description
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.
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.
The SM840051 provides ultra-low jitter, and consumes low
power.
Datasheets and support documentation can be found on
Micrel’s web site at: www.micrel.com.
Features
•
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
•
Crystal Frequencies: 20.141601MHz,19.53125MHz, and
19.44MHz
•
Industrial temperature range: –40°C to +75°C
•
Available in 8-pin TSSOP package
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
May 2010
M9999-050710-C
hbwhelp@micrel.com
or (408) 955-1690
Micrel, Inc.
SM840051
Ordering Information
(1)
Part Number
SM840051KA
SM840051KA TR
(2)
Note:
1. Devices are Green, RoHS-compliant and PFOS-compliant.
2. Tape and Reel.
Package
Type
K-8
K-8
Operating Range
-40°C to +75°C
-40°C to +75°C
Package Marking
840051
840051
Lead
Finish
NiPdAu
NiPdAu
Pin Configuration
8-Pin TSSOP (K-8)
Pin Description
Pin Number
1
2
3
4
5
6
7
8
Pin Name
VDDA
OE
XTAL OUT
XTAL IN
FSEL
GND
Q0
VDD
Type
P
I
O
I
I
P
O
P
Pull down
Pull-up
Level
Pin Function
Analog power.
Output Enable: 1 = Enable, 0 = Disable.
Crystal Output.
Crystal Input.
Frequency Select Pin.
Ground.
Single Ended LVCMOS Clock Out.
Core Power.
Configuring the SM840051 (Frequency Table)
Xtal Frequency (MHz)
20.141601
20.141601
19.53125
19.53125
19.44
19.44
FSEL
0
1
0
1
0
1
Output Frequency (MHz)
161.132812
80.566406
156.25
78.125
155.52
77.76
Output Enable
OE
0
1
Output
Disable
Enable
May 2010
2
M9999-050710-C
hbwhelp@micrel.com
or (408) 955-1690
Micrel, Inc.
SM840051
Absolute Maximum Ratings
(1)
Supply Voltage (V
DD
)...................................................+4.6V
Input Voltage (V
IN
) ................................ –0.50V to V
DD
+0.5V
Output Voltage (V
OUT
) .......................... –0.50V to V
DD
+0.5V
Lead Temperature (soldering, 20sec.)....................... 260°C
Storage Temperature (T
s
) .........................–65°C to +150°C
Operating Ratings
(2)
Supply Voltage (V
IN
)............................. +2.375V to +3.465V
Ambient Temperature (T
A
) .......................... –40°C to +75°C
Junction Thermal Resistance
TSSOP (θ
JA
).....................................................150°C/W
DC Electrical Characteristics
V
DD
= 2.5V ±5%; T
A
= –40°C to +75°C, unless noted.
Symbol
V
DD
V
DDA
I
DD
I
DDA
Parameter
Core Supply Voltage
Analog Supply Voltage
Core Supply Current
Analog Supply Current
No load
Condition
Min
2.375
2.375
Typ
2.50
2.50
12
48
Max
2.625
2.625
20
55
Units
V
V
mA
mA
DC Electrical Characteristics
V
DD
= 3.3V ±5%; T
A
= –40°C to +75°C, unless noted.
Symbol
V
DD
V
DDA
I
DD
I
DDA
Parameter
Core Supply Voltage
Analog Supply Voltage
Core Supply Current
Analog Supply Current
No load
Condition
Min
3.135
3.135
Typ
3.30
3.30
15
49
Max
3.465
3.465
25
60
Units
V
V
mA
mA
LVCMOS Electrical Characteristics
V
DD
= 2.5V and 3.3V ±5%; T
A
= –40°C to +75°C, unless noted.
Symbol
V
IH
V
IL
V
OH
V
OL
I
IH
I
IL
I
IH
I
IL
Notes:
1. Exceeding the absolute maximum rating may damage the device.
2. The device is not guaranteed to function outside its operating rating.
Parameter
Input HIGH Voltage
Input LOW Voltage
Output HIGH Voltage
Output LOW Voltage
Input HIGH Current
Input LOW Current
Input HIGH Current
Input LOW Current
Condition
V
DD
= 3.3V ±5%
V
DD
= 2.5V ±5%
V
DD
= 3.3V ±5%
V
DD
= 2.5V ±5%
V
DD
= 3.3V ±5%
V
DD
= 2.5V ±5%
Output Enable input
Output Enable input
FSEL input
FSEL input
Min
2
1.7
-0.30
-0.30
2.6
1.8
Typ
Max
V
DD
+0.3
V
DD
+ 0.3
0.80
0.70
Units
V
V
V
V
V
V
0.5
5
-150
150
-5
V
µA
µA
µA
µA
May 2010
3
M9999-050710-C
hbwhelp@micrel.com
or (408) 955-1690
Micrel, Inc.
SM840051
AC Electrical Characteristics
V
DD
= 2.5V and 3.3V ±5%; T
A
= –40°C to +75°C, unless noted.
Symbol
F
OUT
t
JITTER
t
R
/ t
F
ODC
Parameter
Output frequency
RMS phase jitter @ 156.25MHz
Output rise/fall time
Output Duty Cycle
Integration Range: 1.875M to 20MHz
20% to 80%
100
48
50
Condition
Min
77.76
58
350
52
Typ
Max
162.4
Units
MHz
fs
ps
%
Test Circuit
3.3V Carrier Frequency, 156.25MHz
Offset from Carrier
100Hz
1kHz
10kHz
100kHz
1MHz
10MHz
40MHz
Measured Phase Noise
-85
-122
-130
-127
-140
-165
-166
Unit
dBc/Hz
dBc/Hz
dBc/Hz
dBc/Hz
dBc/Hz
dBc/Hz
dBc/Hz
Crystal Characteristics
(1)
Parameter
Mode of Oscillation
Frequency
Equivalent Series Resistance (ESR)
Shunt Capacitor
Drive Level
Note:
1. Devices are Green, RoHS-compliant and PFOS-compliant
Min
19.44
Typ
Max
20.3
50
7
1
Units
MHz
Ω
pF
mW
Fundamental Parallel Resonant
May 2010
4
M9999-050710-C
hbwhelp@micrel.com
or (408) 955-1690
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)
May 2010
5
M9999-050710-C
hbwhelp@micrel.com
or (408) 955-1690
京公网安备 11010802033920号
Copyright © 2005-2026 EEWORLD.com.cn, Inc. All rights reserved
电子工程世界
