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SM840004-11
62.5/125MHz Gigabit Ethernet, 4 Output, Ultra-Low Jitter Clock Synthesizer
General Description
Features
The SM840004-11 clock synthesizer was designed for * Generates 4 optimized LVCMOS clock outputs Gigabit Ethernet applications. The device design is * RMS phase jitter @ 125MHz: ~55 fs (typ) optimized for 62.5MHz and 125MHz using a standard * Integrated loop filter components 25MHz fundamental parallel resonant crystal, with * Operates with either a 3.3V or 2.5V supply unparalleled stability and accuracy over the full operating * Power consumption 65mA (typ @ 2.5V) range, and provides an easy fit for Jitter and Phase Noise standards for these high performance interfaces. * Selectable output frequency: 125MHz or 62.5MHz The SM840004-11 design includes a unique power * Input frequency of 25MHz reduction methodology, along with a patented * Fundamental parallel resonant crystal interface RotaryWaveTM architecture, that provides a stable clock * Pin compatible with the ICS/IDT840004-11 with very low noise for optimized performance. This yields * Industrial temperature range: -40C to +85C an overall improved Bit Error Rate (BER) and improved waveform integrity. * Green, RoHS-compliant and PFOS-compliant Datasheets and support documentation can be found on Micrel's web site at: www.micrel.com. ___________________________________________________________________________________________________________
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
July 2010
M9999-070110-A hbwhelp@micrel.com or (408) 955-1690
Micrel, Inc.
SM840004-11
Ordering Information(1)
Part Number SM840004-11KA SM840004-11KA TR
Note: 1. Devices are Green, RoHS-compliant and PFOS-compliant.
Package Type K-20 K-20
Operating Range Industrial Industrial
Package Marking 840004-11 840004-11
Pin Configuration
20-Pin TSSOP (K-20)
Pin Description
Pin Number 1 2,3,4,6,7,9,20 5 8 10 11 12 13,19 14 15 16 17 18 Pin Name F_SEL NC OE VDDA VDD XTAL_OUT XTAL_IN GND Q3 Q2 VDDO Q1 Q0 I P P O I P O O P O O Type I Level Pull-up NC Pull-up Pin Function Frequency Select Pin. No Connect. Do Not Use. Output Enable: (1=Active, 0=High-Z) Analog Power. Core Power. Crystal Out. Crystal In. Ground. Single Ended LVCMOS Clock Out-3. Single Ended LVCMOS Clock Out-2. Output Power Supply. Single Ended LVCMOS Clock Out-1. Single Ended LVCMOS Clock Out-0.
Configuration Table
F_SEL 0 1 M/N Ratio 2.5 5 M Divider 130 130 N Divider 52 26 Output Frequency (MHz) 62.5 125
July 2010
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Micrel, Inc.
SM840004-11
Absolute Maximum Ratings(1)
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.)....................... 260C Storage Temperature (Ts) .........................-65C to +150C
Operating Ratings(2)
Supply Voltage (VIN)............................. +2.375V to +3.465V Ambient Temperature (TA) .......................... -40C to +85C Junction Thermal Resistance TSSOP (JA).....................................................113C/W
DC Electrical Characteristics
VDD = 2.5V 5%; TA = -40C to +85C, unless noted.
Symbol VDD VDDA VDDO IDD IDDA IDD0 Parameter Core Supply Voltage Analog Supply Voltage Output Supply Voltage Power Supply Current Analog Supply Current Output Supply Current No Load Condition Min 2.375 2.375 2.375 Typ 2.50 2.50 2.50 0.1 50 15 Max 2.625 2.625 2.625 1 60 23 Units V V V mA mA mA
DC Electrical Characteristics
VDD = 3.3V 5%; TA = -40C to +85C, unless noted.
Symbol VDD VDDA VDDO IDD IDDA IDDO Parameter Core Supply Voltage Analog Supply Voltage Output Supply Voltage Power Supply Current Analog Supply Current Output Supply Current No Load Condition Min 3.135 3.135 3.135 Typ 3.30 3.30 3.30 0.1 50 25 Max 3.465 3.465 3.465 1 60 32 Units V V V mA mA mA
LVCMOS DC Electrical Characteristics
TA = -40C to +85C, unless noted.
Symbol VIH VIL VOH VOL IIH IIL IIH IIL
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 VDD = 3.3V 5% VDD = 2.5V 5% VDD = 3.3V 5% VDD = 2.5V 5% VDD = 3.3V 5% VDD = 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 VDD +0.3 VDD + 0.3 0.80 0.70
Units V V V V V V
0.5 5 -150 150 -5
V A A A A
July 2010
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M9999-070110-A hbwhelp@micrel.com or (408) 955-1690
Micrel, Inc.
SM840004-11
AC Electrical Characteristics
VDD = 2.5V and 3.3V 5%; TA = -40C to +85C, unless noted.
Symbol FOUT tSKEW tJITTER t R / tF ODC Parameter Output Frequency Output to Output Skew RMS Phase Jitter(random) Output Rise/Fall Time Output Duty Cycle 125MHz @ 1.875MHz-20MHz 62.5MHz @ 1.875MHz-20MHz 20% to 80% 62.5MHz & 125MHz 48 55 356 300 50 52 Condition F_SEL = 1 F_SEL = 0 Min Typ 125 62.5 12 Max Units MHz ps fs fs ps %
Test Circuit
3.3V Output Load AC Test Circuit
3.3V Carrier Frequency, 62.5MHz
Offset from Carrier 100Hz 1kHz 10kHz 100kHz 1MHz 1.825MHz 10MHz 20MHz Measured Phase Noise -103 -124 -137 -135 -145 -151 -169 -169 Unit dBc/Hz dBc/Hz dBc/Hz dBc/Hz dBc/Hz dBc/Hz dBc/Hz dBc/Hz
3.3V Carrier Frequency, 125MHz
Offset from Carrier 100Hz 1kHz 10kHz 100kHz 1MHz 1.825 10MHz 20MHz Measured Phase Noise -103 -125 -134 -132 -143 -152 -166 -167 Unit dBc/Hz dBc/Hz dBc/Hz dBc/Hz dBc/Hz dBc/Hz dBc/Hz dBc/Hz
July 2010
4
M9999-070110-A hbwhelp@micrel.com or (408) 955-1690
Micrel, Inc.
SM840004-11
Crystal Characteristics
Parameter Mode of Oscillation Frequency Equivalent Series Resistance (ESR) Shunt Capacitor Drive Level Min Typ 25 50 7 1 Max Units MHz pF mW Fundamental Parallel Resonant
Functional Description
The SM840004-11 provides a high performance and high accuracy solution for a precision clock source at either 62.5MHz or 125MHz derived from a low cost 25MHz Xtal. Four synchronous low skew 12mA capable LVCMOS outputs are provided with tri state controlled via an external pin (OE). The design of the SM840004-11 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 providing high resolution and easy integer divide ratios. Output divider ratios are fixed at either /26 or /52 via the F_SEL pin, and the feedback divider is fixed at /130. Duty Cycle is inherently improved and provides 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 SM840004-11 will operate at either 3.3V or 2.5V supplies.
July 2010
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M9999-070110-A hbwhelp@micrel.com or (408) 955-1690
Micrel, Inc.
SM840004-11
RMS Phase Noise/Jitter
Phase Noise Plot 125MHz @ 3.3V
July 2010
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M9999-070110-A hbwhelp@micrel.com or (408) 955-1690
Micrel, Inc.
SM840004-11
Switching Waveforms
Output Rise/Fall Time
Output-Output Skew
July 2010
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M9999-070110-A hbwhelp@micrel.com or (408) 955-1690
Micrel, Inc. Power Supply Filtering The SM840004-11 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 Loading
SM840004-11
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. 50 Cut Load Cap. 18pF Shunt Cap. Max. 7pF Drive Max. 0.1mW
Figure 2. Power Supply Filter
AT
Crystal Input Interface
July 2010
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M9999-070110-A hbwhelp@micrel.com or (408) 955-1690
Micrel, Inc. Total capacitance seen by crystal = CL = 1 1 (Ct1 + Cb1 + Cd1) + 1 (Ct2 + Cb2 + Cd2)
SM840004-11 Example: CL = 18pF, Cb = 2pF, Cd = 4pF Trim Cap = Ct = 2 (18pF) - (2pF +4pF) = 30pF The SM840004-11has been characterized with 19.44MHz, 18pF parallel resonant crystal. The trim capacitors Ct1 and Ct2 were optimized to minimize the ppm error. 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.
July 2010
9
M9999-070110-A hbwhelp@micrel.com or (408) 955-1690
Micrel, Inc.
SM840004-11
Package Information
20-Pin TSSOP (K-20)
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. (c) 2010 Micrel, Incorporated.
July 2010
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