National Semiconductor ADC121S625B User Manual

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National Semiconductor ADC121S625B User Manual Manual pdf 4 page image

4 http://www.national.comFigure 1 Component and Test Point Locations3.0 Quick StartThe ADC121S625B evaluation board may beused in the Stand-Alone mode to capture datawith a logic analyzer or third party equipment, or itmay be used in the Computer Mode with aWaveVision4 Data Capture (WV4) Board. In bothcases, the data may be analyzed with theWaveVision4 software.3.1 Stand Alone ModeRefer to Figure 1 for locations of test points andmajor components.1. Install an appropriate crystal oscillator intosocket Y2 and short pins 1 & 2 of JP5 (SeeTable 1). Alternatively, connect a signalgenerator with TTL logic levels to BNCconnector J6 and short pins 2 & 3 of JP5. Ineither case, short pins 4 & 10 of J4 to providethe clock signal to the ADC121S625. If usingan external source, remove the oscillator fromY2. If using an oscillator at Y2, remove thesignal source from J6. The presence of asecond clock source could add noise to theconversion process.2. Connect a clean analog (non-switching) +5Vpower source to Power Connector J5.3. Short pins 1 & 2 of JP3 and turn on the powersupply.4. Dynamic differential signal sources centeredaround ground should be connected acrosspins 1 & 3 of J2. Pin 2 of J2 is ground. If thesource has a 50Ω output impedance, install a51 ohm resistor at R4. Otherwise, the signallevel will be twice as large as expected. Toaccurately evaluate the performance of theADC121S625, the source must be better than90dB THD.5. Short pins 1 & 2 and pins 3 & 4 of JP2 toprovide the bias voltage of VREF for the inputto the ADC when driving the ADC from J2.6. Differential DC sources or dynamic differentialsignal sources centered at a DC bias pointshould be connected across pins 1 & 3 of J3.Pin 2 of J3 is ground.7. Remove the shorts across pins 1 & 2 and pins3 & 4 of JP2 when driving the ADC input fromJ3.8. Select the 2.5V shunt voltage reference asVREF by shorting pins 2 & 3 of JP1 or selectVA as VREF by shorting pins 1 & 2 of JP1. If itis desirable to provide an external referencevoltage, the jumper must be removed fromJP1 and pin 2 may be driven directly.9. The digital inputs and outputs are available forprobing at J4.3.2 Computer ModeRefer to Figure 1 for locations of test points andmajor components.1. Run the WaveVision4 program. Version 4.2or higher is required to interface the WV4board with the ADC121S625B evaluationboard. While the program is loading, continuebelow.2. Install an appropriate crystal oscillator intosocket Y2 and short pins 1 & 2 of JP5 (SeeTable 1). Alternatively, connect a signalgenerator with TTL logic levels to BNCconnector J6 and short pins 2 & 3 of JP5.3. Connect a USB cable between theWaveVision4 Data Capture Board and the PCrunning the WaveVision4 program.4. Connect a ribbon cable (order numberWV4ADCIFCABLE) between J4 of theADC121S625B evaluation board and J3 of theWV4 board.5. Connect a clean analog (non-switching) +5Vpower source to Power Connector J5.6. Short pins 1 & 2 of JP3 and turn on the powersupply. See Section 4.5 for detailed PowerSupply Information7. Connect a separate analog +5V power sourceto power connector J1 on the WV4 board andturn on the power.8. Connect a jumper cable between TP10(+3.3V) of the WV4 board and TP5 (3P3V) ofthe ADC121S625B board.9. Perform steps 4 & 5 or 6 & 7 of section 3.1 todrive the analog inputs.10. Perform step 8 of section 3.1 to select thereference voltage.11. Refer to section 5.0 on Software Operationand Settings.