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How to power the AD5933 evaluation board?

I recently bought  EVAL-AD5933EBZ. 

I have a question to ask before using the device: 

Will, connecting the eval-board to computer PC ,going to power the onboard components like AD5933 , MCU and others ? or I have to design separate power supply.

Please reply

  • Please refer to your board user guide UG-364. On the first page it says: "The user has the option to power the entire circuitry from the USB port of a computer." Most likely the board has arrived configured to be powered from the USB port. You can double-check by making sure the jumpers on the board are set as described in Table 1. of the guide: LK5 should be in place and LK6 in position A, also refer to Figure 33. Linear Regulator on the EVAL-AD5933EB Evaluation Board.

  • Thanks, 

    Coming to calibration of the evaluation board,

    I don't find any option to adjust the feedback resistor (RFB) in the front panel of the evaluation board software. While reading the user guide UG-364, I found this " note RFB = 200 kΩ. Is it already programmed value. Cant we change this value ? How to change RFB in the evaluation board? Please reply. 

  • You do not need to change RFB in the software: it is factored in the gain calculation based on the data produced by the chip in response to calibration resistor.
    You certainly can and should change the RFB value by installing the through-hole resistor between the two female sockets on the board where it is marked "RFB," see the picture, near the bottom of the upper right quadrant. Perhaps this resistor is already installed on the board and it's value is probably 200k.

  • Hi,

    I bought AD5933 chip separately. I tested with multimeter , it showed pins 12, 13 and 14 are internally shorted. Is it so ? Please help.

  • Only somebody from ADI can answer this question as the official documentation is silent regarding this matter. If you look at the schematic on p. 23 of the UG-364 pin 12 is connected to a separate ground, which would imply that pin 12 is connected to a separate internal circuit, but without documentation it is all still just guessing and speculation.

  • can you help this customer with their question please?

  • Hello!. I started using the UG-364(ad5933 eval board).. I am able to get 1kHz to 100kHz frequency sweep. Can the eval-board give the sweep for lower frequencies that is less than 1K..

    And second question is how to generate single repeat frequency using eval board software. I dont see any option in software GUI. Please help how to do this.

  • The AD5933 can synthesize frequencies much lower than 1 KHz: programming Start Frequency Code = 1 into the chip would result in about 0.03 Hz output frequency at MCLK = 16 MHz. Unfortunately the chip cannot accurately measure at low frequencies due to certain systematic errors introduced by the AD5933-specific implementation of the "DFT." Those errors start showing below about 10 KHz and, roughly speaking, keep growing as the frequency is reduced. The most straightforward way around is supplying lower external MCLK frequency to the chip.

    The easiest way to generate repeats of the same frequency is by typing "0" into the frequency increment field of the demo software, then the board will generate the number of repeats equal to the number of frequency points in the sweep.

  • Thanks.

    For the first question, 

    Is there external MCLK oscillator on Evaluation board. Can I reduce the frequency by typing in  low freq value, instead of 16.7 MHz in the GUI software associated with eval. Board. 

    Or do I need to add a seperate oscillator to board. 

  • The board should have a quartz oscillator that supplies the external 16 MHz MCLK to the chip. 16.776 MHz is the internal RC oscillator built into the chip. You can select between the two in the demo software under "System Clock" "External" "Internal" radio buttons, see p.7 in the Manual.

    Or do I need to add a seperate oscillator to board.

    In the same manual see p. 23, Fig, 37: you can disconnect LK3, keep LK4 connected and connect the cable from some suitable general-purpose lab generator digital output or hand-made external oscillator to the CLK1 connector and control the external MCLK frequency.