SY89474U Precision LVDS 2:1 Multiplexer with 1:2 Fanout and Internal Termination General Description The SY89474U is a 2.5V precision, high-speed 2:1 differential MUX capable of processing clocks up to 2.5GHz and data up to 2.5Gbps. The differential input includes Micrel’s unique, 3-pin input termination architecture that directly interfaces to any differential signal (AC- or DC-coupled) as small as 100mV (200mVPP) without any level shifting or termination resistor networks in the signal path. The output is 325mV LVDS with fast rise/fall times guaranteed to be less than 150ps. The SY89474U operates from a 2.5V ±5% supply and is guaranteed over the full industrial temperature range of -40°C to +85°C. The SY89474U is part of Micrel’s highspeed, Precision Edge® product line. For multiple clock switchover solutions, please refer to the SY89840U– SY89845U family. All support documentation can be found on Micrel’s web site at: www.micrel.com. Functional Block Diagram ® Precision Edge Features • Selects between two input channels and provides two copies of the selected input • Guaranteed AC performance over temperature and supply voltage: − DC to 2.5Gbps data throughput − DC to 2.5GHz fMAX (clock) − <470ps In-to-Out tpd − <150ps tr/tf − <20ps output-to-output skew • Unique, patent-pending input isolation design minimizes crosstalk • Ultra-low jitter design: − <1psRMS random jitter − <10psPP deterministic jitter − <1psRMS cycle-to-cycle jitter − <10psPP total jitter (clock) − <0.7psRMS crosstalk induced jitter • Unique patent-pending input termination and VT pin accepts DC- and AC-coupled inputs (CML, PECL, LVDS) • 325mV LVDS output swing • 2.5V ±5% 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 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 August 2005 M9999-081105 [email protected] or (408) 955-1690 Micrel, Inc. SY89474U Ordering Information (1) Part Number Package Type Operating Range Package Marking Lead Finish SY89474UMG QFN-24 Industrial 474U with Pb-Free bar-line indicator NiPdAu Pb-Free SY89474UMGTR (2) QFN-24 Industrial 474U with Pb-Free bar-line indicator NiPdAu Pb-Free Notes: 1. Contact factory for die availability. Dice are guaranteed at TA = 25°C, DC Electricals Only. 2. Tape and Reel. Pin Configuration 24-Pin QFN August 2005 2 M9999-081105 [email protected] or (408) 955-1690 Micrel, Inc. SY89474U Pin Description Pin Number Pin Name 5, 2, IN0, /IN0 23, 20 IN1, /IN1 3, 21 VREF-AC0, VREF-AC1 4, 22 VT0, VT1 1, 6, 9, 10, 13, 19, 24 VCC 7, 8 11, 12 Q0, /Q0 Q1, /Q1 15 SEL 14, 17, 18 GND, Exposed Pad 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 (200mVpp). Note that these inputs will default to an undetermined state if left open. Each pin of a pair internally terminates to a VT pin through 50Ω. Please refer to the “Input Interface Applications” section for more details. Reference Voltage: These outputs bias to VCC -1.2V. They are used for ACcoupling inputs IN and /IN. Connect VREF-AC directly to the corresponding VT pin. Bypass with 0.01µF low ESR capacitor to VCC. Maximum sink/source current is ±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 VT pin. The VT0 and VT1 pins provide a center-tap to a termination network for maximum interface flexibility. Please refer to the “Input Interface Applications” section for more details. Positive Power Supply: Connect to +2.5V ±5% power supply. Bypass with 0.1µF//0.01µF low ESR capacitors as close to VCC pins as possible. Differential Outputs: These differential LVDS output pairs are a logic function of the IN0, IN1, and SEL inputs. Please refer to the truth table below for details. Unused output pairs should be terminated with 100Ω across the outputs. 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 and will default to a logic HIGH state if left open. VTH = VCC/2. Please refer to the “Timing Diagram” section for more details. Ground: Ground pins and exposed pad must be connected to the same ground plane. Truth Table INPUTS August 2005 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 3 M9999-081105 [email protected] or (408) 955-1690 Micrel, Inc. SY89474U Absolute Maximum Ratings(1) Operating Ratings(2) Supply Voltage (VCC)........................... +2.375V to +2.625V Ambient Temperature (TA) ......................... –40°C to +85°C Package Thermal Resistance(3) QFN (θJA) Still-Air .............................................................50°C/W QFN (ΨJB) Junction-to-Board.............................................30°C/W Supply Voltage (VCC) ........................................... -0.5V to +4.0V Input Voltage (VIN) ...................................................-0.5V to VCC Termination Current IN, /IN.......................................................................±50mA VT ...........................................................................±100mA VREF-AC Current Source/sink Current on VREF-AC ..................................±2mA Lead Temperature (soldering, 20 sec.) .......................... +260°C Storage Temperature (TS) ..................................-65°C to 150°C DC Electrical Characteristics(4) TA = –40°C to +85°C; unless otherwise stated. Symbol Parameter VCC Power Supply Condition Min Typ Max Units 2.375 2.5 2.625 V ICC Power Supply Current 80 110 mA RIN Input Resistance (IN-to-VT) No load, max VCC. 45 50 55 Ω RDIFF_IN Differential Input Resistance (IN-to-/IN) 90 100 110 Ω VIH Input High Voltage (IN, /IN) 1.2 VCC V VIL Input Low Voltage (IN, /IN) 0 VIH-0.1 V VIN Input Voltage Swing (IN, /IN) See Figure 1a. Note 5. 0.1 VCC V VDIFF_IN Differential Input Voltage Swing |IN-/IN| See Figure 1b. 0.2 VT_IN IN-to-VT (IN, /IN) VREF-AC Output Reference Voltage VCC-1.3 V VCC-1.2 1. 28 V VCC-1.1 V 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. θJA and ΨJB 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. VIN (max) is specified when VT is floating. August 2005 4 M9999-081105 [email protected] or (408) 955-1690 Micrel, Inc. SY89474U LVDS Outputs DC Electrical Characteristics(6) VCC = 2.5V ±5%; TA = -40°C to + 85°C; RL = 100Ω across output pair; unless otherwise stated Symbol Parameter Condition Min Typ Max Units VOUT Output Voltage Swing Q, /Q See Figure 1a 250 325 mV VDIFF_OUT Differential Output Voltage Swing Q, /Q See Figure 1b 500 650 mV VOCM Output Common Mode Voltage ΔVOCM Change in VOS between complementary output states 1.125 1.275 V -50 +50 mV Max Units LVTTL/CMOS DC Electrical Characteristics(6) VCC = 2.5V ±5%; TA = -40°C to + 85°C; unless otherwise stated Symbol Parameter Condition Min VIH Input HIGH Voltage VIL Input LOW Voltage IIH Input HIGH Current -125 IIL Input LOW Current -300 Typ 2.0 V 0.8 V 30 µA µA Notes: 6. The circuit is designed to meet the DC specifications shown in the above table after thermal equilibrium has been established. August 2005 5 M9999-081105 [email protected] or (408) 955-1690 Micrel, Inc. SY89474U AC Electrical Characteristics(7) VCC = 2.5V ±5%; TA = -40°C to + 85°C; RL = 100Ω across output pair; unless otherwise stated Symbol Parameter Condition fMAX Maximum Operating Frequency VOUT ≥ 200mV Min Typ Max Units NRZ Data 2.5 3.2 Gbps Clock 2.5 4 GHz 220 320 470 ps 200 350 550 ps tpd Differential Propagation Delay In-to-Q tpd Tempco Differential Propagation Delay Temperature Coefficient tSKEW Output-to-Output Skew Note 8 20 ps Part-to-Part Skew Note 9 200 ps Random Jitter Note 10 1 psRMS Deterministic Jitter Note 11 10 psPP SEL-to-Q tJitter Data Clock tr, tf VTH = VCC/2 fs/oC 158 5 Cycle-to-cycle Jitter Note 12 1 psRMS Total Jitter Note 13 10 psPP Crosstalk-Induced Jitter Note 14 0.7 psRMS Output Rise/Fall Time (20% to 80%) At full output swing. 150 ps 30 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 ≤ fMAX. 23 11. Deterministic Jitter is measured with both K28.5 and 2 -1 PRBS pattern, measured at ≤ fMAX. 12. Cycle-to-cycle jitter definition: The variation of periods between adjacent cycles, Tn – Tn-1 where T is the time between rising edges of the output signal. 12 13. Total Jitter definition: With an ideal clock input of frequency <fMAX, no more than one output edge in 10 output edges will deviate by more than the specified peak-to-peak jitter value. 14. Crosstalk is measured at the output while applying two similar differential clock frequencies that are asynchronous with respect to each other at the inputs. August 2005 6 M9999-081105 [email protected] or (408) 955-1690 Micrel, Inc. SY89474U Typical Operating Characteristics VCC = 2.5V ±5%; VIN > 400mV; TA = 25°C, RL = 100Ω across output pair; unless otherwise stated. Functional Characteristics VCC = 2.5V ±5%; VIN > 400mV; TA = 25°C, RL = 100Ω across output pair; unless otherwise stated. August 2005 7 M9999-081105 [email protected] or (408) 955-1690 Micrel, Inc. SY89474U Single-Ended and Differential Swings Figure 1a. Single-Ended Voltage Swing Figure 1b. Differential Voltage Swing Timing Diagrams Input and Output Stages Figure 2. Simplified Differential Input Stage August 2005 8 M9999-081105 [email protected] or (408) 955-1690 Micrel, Inc. SY89474U Input Interface Applications Option: may connect VT to VCC. Figure 3a. LVPECL Interface (DC-Coupled) Figure 3b. LVPECL Interface (AC-Coupled) Figure 3d. CML Interface (AC-Coupled) Figure 3e. LVDS Interface (DC-Coupled) August 2005 9 Figure 3c. CML Interface (DC-Coupled) M9999-081105 [email protected] or (408) 955-1690 Micrel, Inc. SY89474U LVDS Output Interface Applications LVDS specifies a small swing of 325mV typical, on a nominal 1.20V common mode above ground. The common mode voltage has tight limits to permit large variations in ground between an LVDS driver and receiver. Also, change in common mode voltage, as a function of data input, is kept to a minimum, to keep EMI low. Figure 4a. LVDS Differential Measurement Figure 4b. LVDS Mode Measurement Related Product and Support Information Part Number Function Data Sheet Link SY89473U Precision LVPECL 2:1 Multiplexer with 1:2 Fanout and Internal Termination www.micrel.com/product-info/products/sy89473u.shtml HBW Solutions New Products and Applications www.micrel.com/product-info/products/solutions.shtml August 2005 10 M9999-081105 [email protected] or (408) 955-1690 Micrel, Inc. SY89474U Package Information 24-Pin (4mm x 4mm) 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. August 2005 11 M9999-081105 [email protected] or (408) 955-1690