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. 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. • 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 [email protected] or (408) 955-1690 Micrel, Inc. SM840051 Ordering Information(1) Part Number Package Type Operating Range Package Marking Lead Finish K-8 -40°C to +75°C 840051 NiPdAu K-8 -40°C to +75°C 840051 NiPdAu SM840051KA (2) SM840051KA TR Note: 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 Type Level Pin Function 1 VDDA P 2 OE I Pull-up Output Enable: 1 = Enable, 0 = Disable. 3 XTAL OUT O Crystal Output. 4 XTAL IN I Crystal Input. 5 FSEL I 6 GND P Ground. 7 Q0 O Single Ended LVCMOS Clock Out. 8 VDD P Core Power. Analog power. Pull down Frequency Select Pin. Configuring the SM840051 (Frequency Table) Xtal Frequency (MHz) FSEL Output Frequency (MHz) 20.141601 0 161.132812 20.141601 1 80.566406 19.53125 0 156.25 19.53125 1 78.125 19.44 0 155.52 19.44 1 77.76 Output Enable May 2010 OE Output 0 Disable 1 Enable 2 M9999-050710-C [email protected] or (408) 955-1690 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 Max Units VDD Core Supply Voltage 2.375 2.50 2.625 V VDDA Analog Supply Voltage 2.375 2.50 2.625 V IDD Core Supply Current IDDA Analog Supply Current No load 12 20 mA 48 55 mA Typ Max Units DC Electrical Characteristics VDD = 3.3V ±5%; TA = –40°C to +75°C, unless noted. Symbol Parameter Condition Min VDD Core Supply Voltage 3.135 3.30 3.465 V VDDA Analog Supply Voltage 3.135 3.30 3.465 V IDD Core Supply Current 15 25 mA IDDA Analog Supply Current 49 60 mA No load LVCMOS Electrical Characteristics VDD = 2.5V and 3.3V ±5%; TA = –40°C to +75°C, unless noted. Symbol Parameter VIH Input HIGH Voltage VIL Input LOW Voltage VOH Output HIGH Voltage Max Units VDD = 3.3V ±5% Condition Min 2 Typ VDD +0.3 V VDD = 2.5V ±5% 1.7 VDD + 0.3 V VDD = 3.3V ±5% -0.30 0.80 V VDD = 2.5V ±5% -0.30 0.70 V VDD = 3.3V ±5% 2.6 V VDD = 2.5V ±5% 1.8 V VOL Output LOW Voltage IIH Input HIGH Current Output Enable input IIL Input LOW Current Output Enable input IIH Input HIGH Current FSEL input IIL Input LOW Current FSEL input 0.5 V 5 µA -150 µA 150 -5 µA µA Notes: 1. Exceeding the absolute maximum rating may damage the device. 2. The device is not guaranteed to function outside its operating rating. May 2010 3 M9999-050710-C [email protected] or (408) 955-1690 Micrel, Inc. SM840051 AC Electrical Characteristics VDD = 2.5V and 3.3V ±5%; TA = –40°C to +75°C, unless noted. Symbol Parameter Condition FOUT Output frequency Min Typ 77.76 tJITTER RMS phase jitter @ 156.25MHz Integration Range: 1.875M to 20MHz t R / tF Output rise/fall time 20% to 80% ODC Output Duty Cycle Max Units 162.4 MHz 350 ps 52 % 58 100 48 50 fs Test Circuit 3.3V Carrier Frequency, 156.25MHz Offset from Carrier Measured Phase Noise Unit 100Hz -85 dBc/Hz 1kHz -122 dBc/Hz 10kHz -130 dBc/Hz 100kHz -127 dBc/Hz 1MHz -140 dBc/Hz 10MHz -165 dBc/Hz 40MHz -166 dBc/Hz Crystal Characteristics(1) Parameter Min Mode of Oscillation Frequency Typ Max Units Fundamental Parallel Resonant 20.3 MHz Equivalent Series Resistance (ESR) 19.44 50 Ω Shunt Capacitor 7 pF Drive Level 1 mW Note: 1. Devices are Green, RoHS-compliant and PFOS-compliant May 2010 4 M9999-050710-C [email protected] or (408) 955-1690 Micrel, Inc. SM840051 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 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. 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 [email protected] or (408) 955-1690 Micrel, Inc. SM840051 Switching Waveforms May 2010 6 M9999-050710-C [email protected] or (408) 955-1690 Micrel, Inc. SM840051 Power Supply Filtering 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 Loading 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.) Figure 2. Power Supply Filter Equivalent Series Resistance (ESR) Max. Cut Load Cap. Shunt Cap. Max. Drive Max. 50Ω AT 18pF 7pF 0.1mW Crystal Input Interface May 2010 7 M9999-050710-C [email protected] or (408) 955-1690 Micrel, Inc. SM840051 Total capacitance seen by crystal = CL = 1 1 (Ct1 + Cb1 + Cd1) May 2010 + 1 (Ct2 + Cb2 + Cd2) 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. 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. 8 M9999-050710-C [email protected] or (408) 955-1690 Micrel, Inc. SM840051 Board Layout May 2010 9 M9999-050710-C [email protected] or (408) 955-1690 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. May 2010 10 M9999-050710-C [email protected] or (408) 955-1690