ISL5314EVAL2 User`s Manual
Contents
1. a new value into one of the hexadecimal text boxes labeled center frequency register The format is 0x00 where Ox is a constant prefix The analog output of the DDS should now be 5MHz or whatever was programmed A step size input box is located under both the center and offset frequency input boxes The purpose of this box is for the user to be able to set a step size and then quickly evaluate a range of output frequencies by hitting the up and down arrows on their keyboard or by mouse clicking the arrows next to the step size boxes Changing the Board Configuration To drive the DDS with an external clock source remove the oscillator U1 or install jumper J2 which will disable the crystal Drive the external clock into J8 Install J3 so that the external signal source will be loaded with 50Q on the evaluation board Change the Clock Frequency text box on the front panel of the software to match the actual frequency used The board is normally configured for differential to single ended output with transformer coupling J11 For single ended loading using IOUTA J10 install a OQ resister at R48 and remove J5 and J15 next to the transformer as well as R45 and R46 Ensure that R19 and J40 are not populated and that R43 is populated with a resistor that does not violate the output voltage compliance range typically 50Q Performance Notes 1 Lab testing has shown that the transformer has little or no bene2. aximum DDS clock rate with a 3 3V digital supply is 1OOMSPS Schematics and Board Plots The board schematic and layout can be found on the Intersil website by doing a product search on ISL5314 and selecting the link to the ISL5314IN 2 intersil Application Note 9909 All Intersil products are manufactured assembled and tested utilizing ISO9000 quality systems Intersil Corporation s quality certifications can be viewed at www intersil com design quality Intersil products are sold by description only Intersil Corporation reserves the right to make changes in circuit design and or specifications at any time without notice Accordingly the reader is cautioned to verify that data sheets are current before placing orders Information furnished by Intersil is believed to be accurate and reliable However no responsibility is assumed by Intersil or its subsidiaries for its use nor for any infringements of patents or other rights of third parties which may result from its use No license is granted by implication or otherwise under any patent or patent rights of Intersil or its subsidiaries Sales Office Headquarters NORTH AMERICA Intersil Corporation 7585 Irvine Center Drive Suite 100 Irvine CA 92618 TEL 949 341 7000 FAX 949 341 7123 Intersil Corporation 2401 Palm Bay Rd Palm Bay FL 32905 TEL 321 724 7000 FAX 321 724 7946 EUROPE Intersil Europe Sarl Ave C F Ramuz 43 CH 1009 Pully Swit
3. fit to the harmonic performance of the analog output This is due to a mismatch in IOUTA and IOUTB For a more cost effective solution the user may decide to use the single ended configuration IOUTA or IOUTB which is simply to put a resistor between IOUTA and ground that forms a voltage with the current output of the DDS The maximum output current is 20mA A 50 load with full scale current will be a 1V signal The maximum output voltage of the DDS is 1 25V The output current is set with R41 RSET See data sheet for details 2 Using a 5V supply for both the digital and analog supplies of the DDS can improve the SFDR compared to using a 3 3V digital and 5V analog 3 For applications that can provide a 5V supply for both the digital and analog DVDD and AVDD supplies of the DDS the SFDR can be improved by connecting the COMP2 pin of the DDS to AVDD directly This is especially true for DDS CLK to analog output frequency ratios that are less than 4 100M clock 30MHz output for example For ratios greater than 4 this method has little effect This cannot be done unless DVDD AVDD 5V The evaluation board was not configured for this option but a simple wire jumper can be used to prove or disprove its effectiveness The user may wish to build this option into their system in the event that it improves the harmonic performance during evaluation 4 The maximum DDS clock rate is 125MSPS with a 5V digital supply The m
4. intersil Application Note Description The ISL5314EVAL2 provides a means of evaluating the Intersil ISL5314 125MSPS Direct Digital Synthesizer DDS The board is controlled with software that allows for any clock frequency and output frequency within the abilities of the ISL5314 to be evaluated The interface between the PC and the evaluation board is via the parallel port of an IBM compatible PC The analog output of the DDS can be analyzed on external measuring equipment typically either a spectrum analyzer or an oscilloscope The clock source for the DDS can either be a user changeable crystal or an external signal generator provided through an SMA connector The board is shipped with a 125MSPS crystal The complementary analog outputs of the DDS are processed through a 1 1 transformer The board can be reconfigured to bypass the transformer and only a single ended output used Because there is an on chip comparator the means to process the analog sinewave from the DDS output into the comparator inputs is provided for square wave generation The comparator s output is provided via an SMA connector Consult the data sheet of the ISL5314 for details of the DDS s capabilities Features e GUI software control via parallel port Clock On board crystal socket or externally applied e 1 1 RF transformer for analog output Ordering Information PART NUMBER PACKAGE ISL5314EVAL2 Evaluation Board Evaluation Board B
5. lock Diagram PARALLEL aie PORT TEST CONNECTOR HEADER CYPRESS CPLD 1 EXT CLK IN SMA ISL5314EVAL2 User s Manual September 2001 AN9909 2 Getting Started The ISL5314EVAL2 is relatively easy to operate The required equipment is as follows ISL5314EVAL2 evaluation board Printer extension cable DB25 male to female Clock source either crystal or signal generator Latest version of the software 5V 500mA power supply 1 RF cable with an SMA connector Spectrum analyzer or oscilloscope NOOR OND Software Download Regardless of the version of the software that is shipped with the board it is recommended that the user obtain the latest version Go to www intersil com and do a product datasheet search on the ISL5314 Select the link to the ISL5314IN In the related documents section select the link to the DDS software The link will download an installation program Run the installation Follow the instructions on the screen After the program is installed it will automatically run the software If the computer has a non NT based operating system the software should work immediately provided the parallel port address on the Board panel of the software is correct default is 378 If the operating system is NT based it is likely that the user will need to close the DDS software find the directory in which it was installed default is c ISL5314EVAL2 and run the port95nt exe program once Afte
6. r restarting the computer run the ISL5314x exe software located in the directory selected during installation Once the port95nt exe program is run on a computer it should not have to be executed a second time LP FILTER r COMP IN ISL5314 O COMPOUT SMA 1 CAUTION These devices are sensitive to electrostatic discharge follow proper IC Handling Procedures 1 888 INTERSIL or 321 724 7143 Intersil and Design is a trademark of Intersil Americas Inc Copyright Intersil Americas Inc 2001 All Rights Reserved Application Note 9909 Setup Instructions Verify the following board jumper settings J2 OPEN crystal enabled J3 OPEN 50Q Load for external clock disabled J7 OPEN CPLD programming disabled J37 SHORT internal DAC reference enabled The board is shipped with a 125MHz crystal clock source included To confirm that the board is working properly it is recommended that the user leave the crystal in place and the jumper settings as previously listed After confirmation that the board is working properly the user can change the clock source To begin connect the included printer cable between the IBM compatible PC and J6 of the evaluation board Connect a coaxial cable between J11 IOUT and either a spectrum analyzer or an oscilloscope The input impedance of the measurement equipment should be 509 Connect the power cable to the power jack J14 and to a 5V power supply Turn on the power suppl
7. y Proceed to the Software Instructions Software Instructions If the directions in Software Download have not been completed go back and complete before proceeding With the board powered up and connected to the PC via the parallel port launch the DDS software The DDS software has three control tabs On the Board tab of the software the Parallel Control Bus must be checked before the software will communicate with the eval board Use the DDS Options tab to configure the part for different operating modes The tabs contain default settings the first time the software is executed It remembers most previous settings every subsequent time it is executed The first time the program is executed the clock and center frequencies will be zero On the front panel the user should type 125M into the clock frequency text box and hit the ENTER key Mouse click on the Soft Reset button This should default the center frequency register to 1 4 of the clock frequency Verify on the measurement equipment that there is a sinewave at 31 25MHz coming from J11 on the evaluation board Once this has been verified the user should change the center frequency to something else maximum output frequency is Ye the DDS clock rate To change the center frequency type a different frequency i e 5M into the center frequency register and hit the ENTER key Or change the center frequency register in hexadecimal format by typing
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