Dear friends,
We are trying to design a 125kHz bipolar square waveform generator to communicate with a old digital computer. Its a form of BPSK type digital signaling.
We shall connect the AD5426 thru a SPI bus to the uC, and will be using ADR01 for the 10V reference. For dc isolation, we used a transformer coupling as specified in AN-912. Using the spreadsheet provided, we got the following values,
- Transformer ratio - 1CT:1
- DAC output resistor / termination - 75ohms, 75 ohms (we assumed no reconstruction filter will be required for our application)
- Output load - 75ohms
- Full scale DAC current output - 20mA
- Voltage across the load - 0.354 Vrms (1.000 Vpk-pk)
- Output to be amplified on the isolated side
I am a bit confused how the full scale current output is being calculated for a balanced current output DAC. How do I achieve the 20mA output ??
What will be the maximum current output the DAC AD5426 can deliver ?? How is it being calculated.
For your reference, I have attached a snapshot of the oscilloscope readings of the captured data from the system, you can see the 180 degree phase shift.

Please feel free to share any answer, opinion or criticism. I am here to learn.
With my best regards,
Tapajit Mondal