Low Power, 3GHz, 1:2 LVPECL Fanout Buffer/Translator w/ Internal Termination SY89851U Evaluation Board General Description Features The SY89851U evaluation board is designed for convenient setup and quick evaluation of the device. The boards are optimized to interface directly to a 50Ω oscilloscope. • SY89851U The default evaluation board I/O configuration is ACcoupled. For applications that requires DC-coupled mode, instructions for modifying the board are included. • Evaluation board re-configurable for DC-coupled output Data sheets and support documentation can be found on Micrel’s web site at www.micrel.com. • Single +2.5V or +3.3V power supply • AC-coupled input and output configuration for easy evaluation • Fully assembled and tested Related Documentation • SY89851U, Low Power, 3GHz, 1:2 LVPECL Fanout Buffer/Translator with Internal Termination Data Sheet ____________________________________________________________________________________ Evaluation Board August 2004 M9999-082404 [email protected] or (408) 955-1690 Micrel SY89851U Evaluation Board DC-Coupled Evaluation Board Evaluation Board Description The SY89851U evaluation board can be configured in DC-coupled mode by removing capacitors C8-C11 and replacing the components with 0Ω resistors. AC-Coupled Evaluation Board The SY89851U is packaged in a 16-pin MLFTM. The SY89851U evaluation board is designed to operate with a single 2.5V±5% or 3.3V±10% power supply and is configured in AC-coupled mode. Interfacing to 50Ω Lab Equipment Interfacing the board to 50Ω lab equipment in DCcoupled mode involves using split supplies. The high-speed input channels are brought out to SMA connectors through matched length AC-coupled differential strip-line traces. The DC-operating point is set at VCC–1.3V by the VREF-AC output pin, which is connected to the VT input of the device. The outputs are brought out to SMA connectors through matched length AC-coupled differential strip-line traces, which allow the board to interface directly with 50Ω lab equipment. Although the evaluation board’s default mode is AC-coupled the evaluation board can be reconfigured in DC-coupled mode by modifying the board. 2.5V Split Supply Configuration: • VCC = 1.2V • GND = 0V • VEE = –1.3V 3.3V Split Supply Configuration: • VCC = 1.2V • GND = 0V • VEE = –2.1V AC-Coupled Input Interfacing to LVPECL Systems It is recommended that the input be left in AC-coupled input mode for ease of use. In this mode, signals will automatically bias to the correct DC-operating point, which is VCC-1.3V since VREF-AC is connected to the VT input. Therefore, the inputs can be driven by a differential signal as small as 100mV (200mVpp) without any level shifting or termination resistor network in the signal path. Interfacing a DC-coupled output to a LVPECL system requires a single power supply source. Single Power Supply Setup: • VCC = 2.5/3.3V • GND = 0V • VEE = 0V Unused outputs • Single-ended to scope Unused compliment output should be terminated into 50Ω to ground. • Unused output pairs Unused pairs can be left floating with no impact on jitter. August 2004 2 M9999-082404 [email protected] or (408) 955-1690 Micrel SY89851U Evaluation Board Evaluation Board SY89851U AC-Coupled LVPECL Evaluation Board Supply Voltage 2.5V/3.3V 2.5V 3.3V I/O VCC GND VEE C8-C11 (1) 2.5/3.3V 0 0 0.1µF (2) 1.2V 0 –1.3V 0Ω (2) 1.2V 0 –2.1V 0Ω AC-Coupled Input/AC-Coupled Output AC-Coupled Input/DC-Coupled Output AC-Coupled Input/DC-Coupled Output Table 1. SY89851U Evaluation Board Setup Note: 1. Default setting. 2. Remove capacitors at C8-C11 and replace with 0Ω 0402 resistors. August 2004 3 M9999-082404 [email protected] or (408) 955-1690 Micrel SY89851U Evaluation Board AC-Coupled Evaluation Board Setup Setting up the Evaluation Board 3. Turn off or disable the outputs of the signal source. The following steps describe the procedure for setting up the evaluation board: 4. Using equal length 50Ω impedance coaxial cables, connect the signal source to the inputs on the evaluation board. 1. Set VCC to 2.5 or to 3.3V, and GND and VEE to 0V, and turn off the supply. 5. Using equal length 50Ω impedance coaxial cables, connect the outputs of the evaluation board to an oscilloscope or other lab equipment with internal 50Ω termination. 2. Using a differential signal source set the amplitude to 400mV (single-ended) or 800mV (differential). Set the offset to a positive value, the value of the offset is not critical, since the AC-coupled inputs will automatically bias to the VT voltage. August 2004 6. Enable the signal source and monitor the outputs. 4 M9999-082404 [email protected] or (408) 955-1690 Micrel SY89851U Evaluation Board Bill of Materials Item Part Number Manufacturer (1) Description Qty. C1, C3, C5-C11 VJ0402Y104KXXAT Vishay 0.1µF, 25V, 10% Ceramic Capacitor, Size 0402, X7R Dielectric 9 C2, C4 293D685X0010 Vishay(1) 6.8µF, 20V, Tantalum Electrolytic Capacitor, Size C 2 J1 111-0703-001 Johnson Components(2) Black Banana Jack 1 J2 111-0702-001 Johnson Components(2) Red Banana Jack J3 111-0701-001 Johnson Components(2) White Banana Jack 1 SW CT2182LPST-ND 2-Position Dip 1 SMA1-SMA6 142-0701-851 Jack Assembly End Launch SMA 6 U1 SY89851U Low Power, 3GHz, 1:2 LVPECL Fanout Buffer/Translator with Internal Termination 1 Digi-Key (3) Johnson Components(2) Micrel(4) Notes: 1. Vishay: www.vishay.com 2. Johnson Components: www.johnsoncomponents.com 3. Digi-Key: www.digikey.com 4. Micrel: www.micrel.com August 2004 5 M9999-082404 [email protected] or (408) 955-1690 Micrel SY89851U Evaluation Board Evaluation Board Layout PC Board Layout Layer SY89851U The evaluation boards are constructed with Rogers 4003 material and are coplanar in design and fabricated to minimize noise, achieve high bandwidth and minimize crosstalk. L1 GND and Signal L2 GND L3 VCC and VEE L4 GND Table 2. Layer Stack August 2004 6 M9999-082404 [email protected] or (408) 955-1690 Micrel SY89851U Evaluation Board Micrel Cross Reference Application Hints and Notes To find an equivalent Micrel part, go to Micrel’s website at: http://www.micrel.com and following the steps below: For application notes on high speed termination on PECL and LVPECL products, clock synthesizer products, SONET jitter measurement, and other High Bandwidth product go to Micrel’s website at http://www.micrel.com/. Once in Micrel’s website, follow the steps below: 1. Click on Dynamic Cross Reference 2. Enter competitor’s part number in the Dynamic Cross Reference field 1. Click on “Product Info”. 2. In the Applications Information Box, choose “Application Hints and Application Notes.” 3. To download a PDF version of this information, click on the Cross Reference PDF tab HBW Support Hotline: 408-955-1690 Email Support: [email protected] MICREL, INC. 1849 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. © 2004 Micrel, Incorporated. August 2004 7 M9999-082404 [email protected] or (408) 955-1690