SY89473U Precision LVPECL 2:1 Multiplexer with 1:2 Fanout and Internal Termination General Description The SY89473U is a 2.5V/3.3V precision, high-speed 2:1 differential MUX capable of processing clocks up to ® Precision Edge 2.5GHz and data up to 2.5Gbps. The differential input includes Micrel’s unique, 3-pin Features input termination architecture that directly interfaces to • Selects between two input channels and provides two any differential signal (AC- or DC-coupled) as small as copies of the selected output 100mV (200mV ) without any level shifting or PP termination resistor networks in the signal path. The • Guaranteed AC performance over temperature and output is 800mV, 100K-compatible, LVPECL with fast supply voltage: rise/fall times guaranteed to be less than 190ps. -DC to 2.5Gbps data throughput The SY89473U operates from a 2.5V ±5% or 3.3V -DC to 2.5GHz f (clock) MAX ±10% supply and is guaranteed over the full industrial -<500ps In-to-Out t pd temperature range of –40°C to +85°C. The SY89473U is -<190ps t/t part of Micrel’s high-speed, Precision Edge® product -<20ps Ourtfp ut-to-output skew line. For multiple-clock switchover solutions, please refer • Unique patented input isolation design minimizes to the SY89840–SY89843U family. crosstalk All support documentation can be found on Micrel’s web • Ultra-low Jitter Design: site at: www.micrel.com. -<1ps random jitter RMS -<1ps cycle-to-cycle jitter RMS Functional Block Diagram -<10ps total jitter (clock) PP -<0.7ps crosstalk induced jitter RMS • Unique patent-pending input termination and VT pin accepts DC- and AC-coupled inputs (CML, PECL, LVDS) • 800mV (100K) LVPECL output swing • 2.5V ±5% or 3.3V ±10% supply voltage • -40°C to +85°C industrial temperature range • Available in 24-pin (4mm x 4mm) QFN package Applications • Clock switchover • Data distribution Markets • LAN/WAN • Enterprise servers • ATE • Test and measurement United States Patent No. RE44,134 Precision Edge is a registered trademark of Micrel, 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 2007 M9999-052207-B hbwhelp@micrel.com or (408) 955-1690

Micrel, Inc. SY89473U Ordering Information(1) Part Number Package Type Operating Package Marking Lead Range Finish NiPdAu SY89473UMG QFN-24 Industrial 473U with Pb-Free bar-line indicator Pb-Free NiPdAu SY89473UMGTR(2) QFN-24 Industrial 473U with Pb-Free bar-line indicator Pb-Free Notes: 1. Contact factory for die availability. Dice are guaranteed at T = 25°C, DC Electricals Only. A 2. Tape and Reel. Pin Configuration 24-Pin QFN May 2007 2 M9999-052207-B hbwhelp@micrel.com or (408) 955-1690

Micrel, Inc. SY89473U Pin Description Pin Number Pin Name Pin Function Differential Inputs: These input pairs are the differential signal inputs to the device. They accept AC or DC-coupled signals as small as 100mV (200mV ). Note that 5, 2, IN0, /IN0 PP these inputs will default to an indeterminate state if left open. Each pin of a pair 23, 20 IN1, /IN1 internally terminates to a VTpin through 50Ω. Please refer to the “Input Interface Applications” section for more details. Reference Voltage: These outputs bias to V -1.2V. They are used for AC- CC coupling inputs IN and /IN. Connect VREF-AC directly to the corresponding VT pin. VREF-AC0, Bypass with 0.01µF low ESR capacitor to VCC. Maximum sink/source current is 3, 21 VREF-AC1 ±1.5mA. Due to the limited drive capability, the VREF-AC pin is only intended to drive its respective VT pin. Please refer to the “Input Interface Applications” section for more details. Input Termination Center-Tap: Each side of the differential input pair terminates to a VTpin. The VT0 and VT1 pins provide a center-tap to a termination network for 4, 22 VT0 VT1 , maximum interface flexibility. Please refer to the “Input Interface Applications” section for more details. 1, 6, 9, 10, 13, Positive Power Supply: Connect to +2.5V or +3.3V power supply. Bypass with VCC 19, 24 0.1µF//0.01µF low ESR capacitors as close to VCC pins as possible. Differential Outputs: These differential LVPECL output pairs are a logic function of 7, 8 Q0, /Q0 the IN0, IN1, and SEL inputs. Please refer to the truth table below for details. 11, 12 Q1, /Q1 Unused output pairs can be left floating with no impact on jitter. This single-ended TTL/CMOS-compatible input selects the inputs to the multiplexer. Note that this input is internally connected to a 25kΩ pull-up resistor 15 SEL and will default to a logic HIGH state if left open. V = V /2. Please refer to the TH CC “Timing Diagram” section for more details. GND, Exposed Ground: Ground pins and exposed pad must be connected to the same ground 14, 17, 18 Pad plane. Truth Table INPUTS OUTPUTS IN0 /IN0 IN1 /IN1 SEL Q /Q 0 1 X X 0 0 1 1 0 X X 0 1 0 X X 0 1 1 0 1 X X 1 0 1 1 0 May 2007 3 M9999-052207-B hbwhelp@micrel.com or (408) 955-1690

Micrel, Inc. SY89473U Absolute Maximum Ratings(1) Operating Ratings(2) Supply Voltage (V )..................................+2.375V to +2.625V Supply Voltage (V )....................................-0.5V to +4.0V CC CC ....................................................................+3.0V to +3.6V Input Voltage (V )...........................................-0.5V to V IN CC Ambient Temperature (T ).................................–40°C to +85°C LVPECL Output Current (I ) A OUT Package Thermal Resistance(3) Continuous...........................................................±50mA QFN (θ ) Surge..................................................................±100mA JA Still-Air....................................................................50°C/W Input Current QFN (Ψ ) Source/sink Current on IN, /IN..............................±50mA JB Junction-to-Board...................................................30°C/W Source/sink Current on V ..................................±100mA T V Current REF-AC Source/sink Current on V ...............................±2mA REF-AC Lead Temperature (soldering, 20 sec.)...................+260°C Storage Temperature (T )...........................-65°C to 150°C S DC Electrical Characteristics(4) T = –40°C to +85°C; unless otherwise stated. A Symbol Parameter Condition Min Typ Max Units V Power Supply 2.375 2.5 2.625 V CC 3.0 3.3 3.6 V I Power Supply Current No load, max V . 45 65 mA CC CC R Input Resistance 45 50 55 Ω IN (IN-to-V ) T R Differential Input Resistance 90 100 110 Ω DIFF_IN (IN-to-/IN) V Input High Voltage 1.2 V V IH CC (IN, /IN) V Input Low Voltage 0 V -0.1 V IL IH (IN, /IN) V Input Voltage Swing See Figure 1a. Note 5 0.1 V V IN CC (IN, /IN) V Differential Input Voltage Swing See Figure 1b. 0.2 V DIFF_IN |IN-/IN| V IN-to-V 1. 28 V T_IN T (IN, /IN) V Output Reference Voltage V -1.3 V -1.2 V -1.1 V REF-AC CC CC CC Notes: 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 ratings conditions for extended periods may affect device reliability. 2. The data sheet limits are not guaranteed if the device is operated beyond the operating ratings. 3. Package thermal resistance assumes exposed pad is soldered (or equivalent) to the devices most negative potential on the PCB. θ and Ψ JA JB values are determined for a 4-layer board in still air unless otherwise stated. 4. The circuit is designed to meet the DC specifications shown in the above table after thermal equilibrium has been established. 5. V (max) is specified when V is floating. IN T May 2007 4 M9999-052207-B hbwhelp@micrel.com or (408) 955-1690

Micrel, Inc. SY89473U LVPECL Outputs DC Electrical Characteristics(6) V = 2.5V ±5% or 3.3V ±10%; T = -40°C to + 85°C; R = 50Ω to V -2V, unless otherwise stated. CC A L CC Symbol Parameter Condition Min Typ Max Units V Output HIGH Voltage V –1.145 V -0.895 V OH CC CC Q, /Q V Output LOW Voltage V –1.945 V -1.695 V OL CC CC Q, /Q V Output Voltage Swing See Figure 1a. 550 800 mV OUT Q, /Q V Differential Output Voltage Swing See Figure 1b. 1100 1600 mV DIFF-OUT Q, /Q LVTTL/CMOS DC Electrical Characteristics(6) V = 2.5V ±5% or 3.3V ±10%; T = -40°C to + 85°C, unless otherwise stated. CC A Symbol Parameter Condition Min Typ Max Units V Input HIGH Voltage 2.0 V IH V Input LOW Voltage 0.8 V IL I Input HIGH Current -125 30 µA IH I Input LOW Current -300 µA IL Note: 6. The circuit is designed to meet the DC specifications shown in the above table after thermal equilibrium has been established. May 2007 5 M9999-052207-B hbwhelp@micrel.com or (408) 955-1690

Micrel, Inc. SY89473U AC Electrical Characteristics(7) V = 2.5V ±5% or 3.3V ±10%; T = -40°C to + 85°C, R = 50Ω to V -2V, unless otherwise stated. CC A L CC Symbol Parameter Condition Min Typ Max Units f Maximum Operating Frequency NRZ Data 2.5 3.2 Gbps MAX V ≥ 400mV Clock 2.5 3.0 GHz OUT t Differential Propagation Delay pd In-to-Q 250 320 500 ps SEL-to-Q V = V /2 250 360 600 ps TH CC T Differential Propagation Delay pd 158 fs/oC Tempco Temperature Coefficient t Output-to-Output Skew Note 8 5 20 ps SKEW Part-to-Part Skew Note 9 200 ps t Clock Jitter Random Jitter Note 10 1 ps RMS Cycle-to-Cycle Jitter Note 11 1 ps RMS Total Jitter (TJ) Note 12 10 ps PP Crosstalk-Induced Jitter Note 13 0.7 ps RMS t t Output Rise/Fall Time (20% to 80%) At full output swing. 70 130 190 ps r, f Notes: 7. High-frequency AC-parameters are guaranteed by design and characterization. 8. Output-to-output skew is measured between two different outputs under identical transitions. 9. Part-to-part skew is defined for two parts with identical power supply voltages at the same temperature and with no skew of the edges at the respective inputs. 10. Random Jitter is measured with a K28.7 pattern, measured at <f . MAX 11. Cycle-to-cycle jitter definition: The variation of periods between adjacent cycles, T – T where T is the time between rising edges of the n n-1 output signal. 12. Total Jitter definition: With an ideal clock input of frequency <f , no more than one output edge in 1012 output edges will deviate by MAX more than the specified peak-to-peak jitter value. 13. Crosstalk is measured at the output while applying two similar differential clock frequencies that are asynchronous with respect to each other at the inputs. May 2007 6 M9999-052207-B hbwhelp@micrel.com or (408) 955-1690

Micrel, Inc. SY89473U Typical Operating Characteristics V = 3.3V; V > 400mV; T = 25°C, R = 50Ω to V -2V, unless otherwise stated. CC IN A L CC Functional Characteristics V = 3.3V; V > 400mV; T = 25°C, R = 50Ω to V -2V, unless otherwise stated. CC IN A L CC May 2007 7 M9999-052207-B hbwhelp@micrel.com or (408) 955-1690

Micrel, Inc. SY89473U Single-Ended and Differential Swings Figure 1a. Single-Ended Voltage Swing Figure 1b. Differential Voltage Swing Timing Diagrams Input and Output Stages Figure 2a. Simplified Differential Input Stage Figure 2b. Simplified LVPECL Output Stage May 2007 8 M9999-052207-B hbwhelp@micrel.com or (408) 955-1690

Micrel, Inc. SY89473U Input Interface Applications Option: may connect V to V T CC Figure 3a. LVPECL Interface Figure 3b. LVPECL Interface Figure 3c. CML Interface (DC-Coupled) (AC-Coupled) (DC-Coupled) Figure 3d. CML Interface Figure 3e. LVDS Interface (AC-Coupled) (DC-Coupled) May 2007 9 M9999-052207-B hbwhelp@micrel.com or (408) 955-1690

Micrel, Inc. SY89473U LVPECL Output Interface Applications LVPECL has a high input impedance, a very low output impedance (open emitter), and a small signal swing which results in low EMI. LVPECL is ideal for driving 50Ω- and-100Ω-controlled impedance transmission lines. There are several techniques for terminating the LVPECL output including: Parallel Termination-Thevenin Equivalent, Parallel Termination (3-resistor), and AC-coupled Termination. Unused output pairs may be left floating. However, single-ended outputs must be terminated, or balanced. Note: 1. Power-saving alternative to Thevenin termination. 2. Place termination resistors as close to destination inputs as possible. 3. Rb resistor sets the DC bias voltage, equal to V . T 4. For 2.5V systems, Rb = 19Ω. Figure 4b. Parallel Termination (3-Resistor) Note: 1. For +2.5V systems, R1 = 250Ω, R2 = 62.5Ω. Figure 4a. Parallel Termination-Thevenin Equivalent Related Product and Support Information Part Number Function Data Sheet Link SY89474U Precision LVDS 2:1 Multiplexer with www.micrel.com/product-info/products/sy89474u.shtml 1:2 Fanout and Internal Termination SY89475U Precision CML 2:1 Multiplexer with www.micrel.com/product-info/products/sy89475u.shtml 1:2 Fanout and Internal Termination HBW New Products and Applications www.micrel.com/product-info/products/solutions.shtml Solutions May 2007 10 M9999-052207-B hbwhelp@micrel.com or (408) 955-1690

Micrel, Inc. SY89473U Package Information 24-Pin QFN 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. © 2005 Micrel, Incorporated. May 2007 11 M9999-052207-B hbwhelp@micrel.com or (408) 955-1690