SY89847U 1.5GHz Precision, LVDS 1:5 Fanout with 2:1 MUX and Fail Safe Input with Internal Termination General Description The SY89847U is a 2.5V, 1:5 LVDS fanout buffer with a 2:1 differential input multiplexer (MUX). A unique Fail-Safe Input (FSI) protection prevents metastable output conditions when the selected input clock fails to a DC voltage (voltage between the pins of the differential input drops significantly below 100mV). The differential input includes Micrel’s unique, 3-pin internal termination architecture that can interface 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 outputs are LVDS compatible with very fast rise/fall times guaranteed to be less than 210ps. The SY89847U operates from a 2.5V ±5% supply and is guaranteed over the full industrial temperature range of –40°C to +85°C. The SY89847U is part of Micrel’s high-speed, Precision ® Edge product line. All support documentation can be found on Micrel’s web site at: www.micrel.com. Functional Block Diagram Precision Edge ® Features • Selects between two sources, and provides 5 precision LVDS copies • Fail-Safe Input – Prevents outputs from oscillating when input is invalid • Guaranteed AC performance over temperature and supply voltage: – DC-to >1.5GHz throughput – <1000ps Propagation Delay (IN-to-Q) – <210ps Rise/Fall times • Ultra-low jitter design: – <1psRMS random jitter – <1psRMS cycle-to-cycle jitter – <10psPP total jitter (clock) – <0.7psRMS MUX crosstalk induced jitter • Unique, patented MUX input isolation design minimizes adjacent channel crosstalk • Unique, patented internal termination and VT pin accepts DC- and AC-coupled inputs (CML, PECL, LVDS) • Wide input voltage range VCC to GND • 2.5V ±5% supply voltage • -40°C to +85°C industrial temperature range • Available in 32-pin (5mm x 5mm) QFN package Applications • Fail-safe clock protection • Ultra-low jitter LVDS clock distribution • Rack-based Telecom/Datacom 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 June 2007 M9999-060107-B [email protected] or (408) 955-1690 Micrel, Inc. SY89847U Ordering Information(1) Part Number Package Type Operating Range SY89847UMG QFN-32 QFN-32 (2) SY89847UMGTR Package Marking Lead Finish Industrial SY89847U with Pb-Free bar-line Indicator NiPdAu Pb-Free Industrial SY89847U 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 32-Pin QFN June 2007 2 M9999-060107-B [email protected] or (408) 955-1690 Micrel, Inc. SY89847U Pin Description Pin Number Pin Name Pin Function VT0, VT1 Input Termination Center-Tap: Each side of a differential input pair terminates to the VT pin. The VT pin provides a center-tap for each input (IN, /IN) to a termination network for maximum interface flexibility. See “Input Interface Applications” subsection. 2, 3 6, 7 IN0, /IN0 IN1, /IN1 Differential Inputs: These input pairs are the differential signal inputs to the device. These inputs accept AC- or DC-coupled signals as small as 100mV. The input pairs internally terminate to a VT pin through 50 Ω. Each input has level shifting resistors of 3.72kΩ to VCC. This allows a wide input voltage range from VCC to GND. See Figure 3, Simplified Differential Input Stage for details. Note that these inputs will default to a valid (either HIGH or LOW) state if left open. See “Input Interface Applications” subsection. 10, 11, 30, 31 GND, Exposed Pad 1, 8 Ground. Exposed pad must be connected to a ground plane that is the same potential as the ground pins. 4 OE Single-Ended Input: This TTL/CMOS input disables and enables the Q0-Q4 outputs. It is internally connected to a 25kΩ pull-up resistor and will default to a logic HIGH state if left open. When disabled, Q goes LOW and /Q goes HIGH. OE being synchronous, outputs will be enabled/disabled following a rising and a falling edge of the input clock. VTH = VCC/2. 5 SEL Single-Ended Input: 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 logic HIGH state if left open. VTH = VCC/2. 9, 32 VREF-AC1 VREF-AC0 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. Due to limited drive capability, the VREF-AC pin is only intended to drive its respective VT pin. Maximum sink/source current is ±0.5mA. See “Input Interface Applications” subsection. 12, 13, 16, 19, 22, 25, 28, 29 VCC Positive Power Supply: Bypass with 0.1µF||0.01µF low ESR capacitors as close to the VCC pins as possible. 27, 26 24, 23 21, 20 18, 17 15, 14 Q0, /Q0 Q1, /Q1 Q2, /Q2 Q3, /Q3 Q4, /Q4 LVDS Differential Output Pairs: Differential copies of the selected input signal. The output swing is typically 325mV. Used and unused outputs must be terminated with 100Ω across the pair (Q, /Q). These differential LVDS outputs are a logic function of the IN0, IN1, and SEL inputs. See “Truth Table” below. Truth Table Inputs June 2007 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 M9999-060107-B [email protected] or (408) 955-1690 Micrel, Inc. SY89847U Absolute Maximum Ratings(1) Operating Ratings(2) Supply Voltage (VCC) .......................... –0.5V to +4.0V Input Voltage (VIN) ..................................–0.5V to VCC LVPECL Output Current (IOUT) Continuous ................................................. 50mA Surge ........................................................ 100mA Current (VT) Source or sink on VT pin ........................ ±100mA Input Current Source or sink current on (IN, /IN) ........... ±50mA Current (VREF) (4) Source or sink current on VREF-AC ......... ±0.5mA Maximum operating Junction Temperature ..... 125°C Lead Temperature (soldering, 20sec.) ............. 260°C Storage Temperature (Ts) ............... –65°C to +150°C Supply Voltage (VCC).................. +2.375V to +2.625V Ambient Temperature (TA) ................ –40°C to +85°C (3) Package Thermal Resistance QFN (θ JA) Still-Air ..................................................... 50°C/W QFN (ψ JB) Junction-to-Board .................................... 31°C/W DC Electrical Characteristics(5) TA = –40°C to +85°C, unless otherwise stated. Symbol Parameter VCC Power Supply ICC Power Supply Current RIN Input Resistance (IN-to-VT) RDIFF_IN Condition Min Typ Max Units 2.375 2.5 2.625 V 90 130 mA 45 50 55 Ω Differential Input Resistance (IN-to-/IN) 90 100 110 Ω VIH Input High Voltage (IN, /IN) 0.1 VCC V VIL Input Low Voltage (IN, /IN) 0 VIH–0.1 V VIN Input Voltage Swing (IN, /IN) See Figure 2a. Note 6 0.1 1.0 V VDIFF_IN Differential Input Voltage Swing |IN-/IN| See Figure 2b. 0.2 VIN_FSI Input Voltage Threshold that Triggers FSI VREF-AC Output Reference Voltage VT_IN Voltage from Input to VT No load, max VCC IVREF-AC = + 0.5mA V VCC–1.3 30 100 mV VCC–1.2 VCC–1.1 V 1.28 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 rating 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. Due to the limited drive capability, use for input of the same package only. 5. The circuit is designed to meet the DC specifications shown in the above table after thermal equilibrium has been established. 6. VIN (max) is specified when VT is floating. June 2007 4 M9999-060107-B [email protected] or (408) 955-1690 Micrel, Inc. SY89847U LVDS Outputs DC Electrical Characteristics(7) VCC = +2.5V ±5%, RL = 100Ω across the outputs; TA = –40°C to +85°C, unless otherwise stated. Symbol Parameter Condition Min Typ VOUT Output Voltage Swing (Q, /Q) See Figure 2a 250 325 mV VDIFF_OUT Differential Output Voltage Swing |Q – /Q| See Figure 2b 500 650 mV 1.20 VOCM Output Common Mode Voltage (Q, /Q) See Figure 5b 1.125 ∆VOCM Change in Common Mode Voltage (Q, /Q) See Figure 5b –50 Max Units 1.275 V +50 mV Max Units LVTTL/CMOS DC Electrical Characteristics(7) 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 Note: 7. The circuit is designed to meet the DC specifications shown in the above table after thermal equilibrium has been established. June 2007 5 M9999-060107-B [email protected] or (408) 955-1690 Micrel, Inc. SY89847U AC Electrical Characteristics(8) VCC = 2.5V ±5%, RL = 100Ω across the outputs, Input tr/tf < 300ps; TA = –40°C to + 85°C, unless otherwise stated. Symbol Parameter Condition Min Typ fMAX Maximum Operating Frequency VOUT > 200mV, VIN > 200mV 1.5 2.0 GHz VOUT > 200mV, VIN > 100mV 1.0 1.5 GHz tpd Differential Propagation Delay Max Units Tpd varies with input tr/tf IN-to-Q 100mV < VIN < 200mV, Note 9 600 820 1100 ps IN-to-Q 200mV < VIN < 800mV, Note 9 500 720 1000 ps SEL-to-Q VTH = VCC/2 400 600 800 ps tS OE Set-up Time OE-to-IN Note 10 300 ps tH OE Hold Time IN-to-OE Note 10 800 ps tpd Tempco Differential Propagation Delay Temperature Coefficient tSKEW Output-to-Output Skew Note 11 5 20 ps Input-to-Input Skew Note 12 5 15 ps Part-to-Part Skew Note 13 300 ps Random Jitter Note 14 1 psRMS Cycle-to-Cycle Jitter Note 15 1 psRMS Total Jitter tJITTER tr, tf o 256 fs/ C Clock Note 16 10 psPP Crosstalk-Induced Jitter Note 17 0.7 psRMS Output Rise/Fall Time (20% to 80%) At full output swing. 210 ps Duty Cycle VIN >200mV 47 53 % 100mV < VIN < 200mV 45 55 70 120 Notes: 8. High-frequency AC-parameters are guaranteed by design and characterization. 9. Propagation delay is measured with input tr, tf ≤ 300ps (20% to 80%). The propagation delay is a function of the rise and fall times at IN. See “Typical Operating Characteristics” for details. 10. Set-up and hold times apply to synchronous applications that intend to enable/disable before the next clock cycle. For asynchronous applications, set-up and hold do not apply. 11. Output-to-Output skew is measured between two different outputs under identical transitions. 12. Input-to-Input skew is the time difference between the two inputs to one output, under identical input transitions. 13. 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. 14. Random Jitter is measured with a K28.7 character pattern, measured at <fMAX. 15. 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. 16. Total Jitter definition: with an ideal clock input of frequency <fMAX, no more than one output edge in 1012 output edges will deviate by more than the specified peak-to-peak jitter value. 17. Crosstalk is measured at the output while applying two similar differential clock frequencies that are asynchronous with respect to each other at the inputs. June 2007 6 M9999-060107-B [email protected] or (408) 955-1690 Micrel, Inc. SY89847U Functional Description Input Clock Failure Case If the input clock fails to a floating, static, or extremely low signal swing such that the voltage swing across the input pair is significantly less than 100mV, FSI function will eliminate a metastable condition and latch the outputs to the last valid state. No ringing and no undetermined state will occur at the output under these conditions. The output recovers to normal operation once the input signal returns to a valid state with a typical swing greater than 30mV. Note that the FSI function will not prevent duty cycle distortion in case of a slowly deteriorating (but still toggling) input signal. Due to the FSI function, the propagation delay will depend on rise and fall time of the input signal and on its amplitude. Refer to “Typical Operating Characteristics” for detailed information. . Clock Select (SEL) SEL is an asynchronous TTL/CMOS compatible input that selects one of the two input signals. Internal 25kΩ pull-up resistor defaults the input to logic HIGH if left open. Input switching threshold is VCC/2. Refer to Figure 1a. Output Enable (OE) OE is a synchronous TTL/CMOS compatible input that enables/disables the outputs based on the input to this pin. The enable function is synchronous so that the clock outputs will be enabled or disabled following a rising and a falling edge of the input clock. Refer to Figure 1b. Internal 25kΩ pull-up resistor defaults the input to logic HIGH if left open. Input switching threshold is VCC/2. Fail-Safe Input (FSI) The input includes a special fail-safe circuit to sense the amplitude of the input signal and to latch the outputs when there is no input signal present, or when the amplitude of the input signal drops sufficiently below 100mVPK (200mVPP), typically 30mVPK. Refer to Figure 1d. June 2007 7 M9999-060107-B [email protected] or (408) 955-1690 Micrel, Inc. SY89847U Timing Diagrams Figure 1a. SEL-to-Q Delay Figure 1b. Enable Output Timing Diagram Figure 1c. Propagation Delay June 2007 8 M9999-060107-B [email protected] or (408) 955-1690 Micrel, Inc. SY89847U Figure 1d. Fail-Safe Feature Figure 1e. Setup and Hold Time June 2007 9 M9999-060107-B [email protected] or (408) 955-1690 Micrel, Inc. SY89847U Typical Operating Characteristics VCC = 2.5V, GND = 0V, tr / tf ≤ 300ps, VIN = 100mV, RL = 100Ω across the outputs, TA = 25°C, unless otherwise stated. June 2007 10 M9999-060107-B [email protected] or (408) 955-1690 Micrel, Inc. SY89847U Functional Characteristics VCC = 2.5V, GND = 0V, VIN = 250mV, RL = 100Ω across the outputs, TA = 25°C, unless otherwise stated. June 2007 11 M9999-060107-B [email protected] or (408) 955-1690 Micrel, Inc. SY89847U Single-Ended and Differential Swings Figure 2a. Single-Ended Voltage Swing Figure 2b. Differential Voltage Swing Input Stage Figure 3. Simplified Differential Input Stage June 2007 12 M9999-060107-B [email protected] or (408) 955-1690 Micrel, Inc. SY89847U Input Interface Applications Option: may connect VT to VCC Figure 4a. LVPECL Interface (DC-Coupled) Figure 4b. LVPECL Interface (AC-Coupled) Figure 4d. CML Interface (AC-Coupled) Figure 4e. LVDS Interface (DC-Coupled) June 2007 13 Figure 4c. CML Interface (DC-Coupled) M9999-060107-B [email protected] or (408) 955-1690 Micrel, Inc. SY89847U LVDS Output Interface Applications LVDS specifies a small swing of 325mV typical, on a nominal 1.2V common mode above ground. The common mode voltage has tight limits to permit large variations in the ground between and 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 5b. LVDS Common Mode Measurement Figure 5a. LVDS Differential Measurement Related Product and Support Documentation Part Number Function Data Sheet Link SY89846U 1.5GHz Precision, LVPECL 1 :5 Fanout with 2 :1 MUX and Fail Safe Input with Internal Termination www.micrel.com/product-info/products/sy89846u.shtml. HBW Solutions New Products and Applications www.micrel.com/product-info/products/solutions.shtml June 2007 14 M9999-060107-B [email protected] or (408) 955-1690 Micrel, Inc. SY89847U Package Information 32-Pin (5mm x 5mm) QFN Packages Notes: 1. Package meets Level 2 Moisture Sensitivity Classification. 2. All parts are dry-packed before shipment. 3. Exposed pad must be soldered to a ground for proper thermal management. 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. © 2007 Micrel, Inc. June 2007 15 M9999-060107-B [email protected] or (408) 955-1690