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DAC7760: Analog output in industrial applications

Jingtai
Genius 4575 points
Part Number: DAC7760
Other Parts Discussed in Thread: DAC8760

Out application is to output both 0-10V and +/-10V signals, not at the same time, now we have the Launchxl-F28377S already on which the buffered DAC is unipolar output, is it possible to connect some amplifiers to become bipolar output? Otherwise the on chip DAC will be given up and a bipolar output DAC, such as DAC7760, will be required. 

In Spau525 there is a solution to realize bipolar analog output from a unipolar output DAC but it only gets +/-10V rather than both +/-10V and 0-10V as a selection.   

  • 0
    TI__Mastermind 46290 points
    Jingtai,

    I am guessing SPAU525 is intended to refer to SLAU525. This would be my best recommended circuits with some switches introduced in order to have the programmable element of selecting the output range. If you would rather see such functionality in a fully integrated product, the DAC8760 family remains the best choice in my opinion.
  • 0 in reply to Kevin Duke
    Genius 4575 points
    Thanks for your reply. DAC8760 is alright. Can you support us with the solution?
  • 0 in reply to Jingtai
    TI__Mastermind 46290 points

    Jingtai,

    I would be happy to help you design with the DAC8760. Just let me know what help you require.

  • 0 in reply to Kevin Duke
    Genius 4575 points

    The signal is excited with 10 MHz sine wave and is acquired by ADC5560 then processed in Launchxl-F28377S, from the Launchpad the data will be converted to 0-10V or +/-10V, depending customer PLCs. The flow: 10 MHz sine wave - ADC - DSP/MCU - DAC - PLC. One bottleneck maybe is DAC's converting speed because the ADC will convert at least in 10 MHz, the DSP/MUC will run software that takes some time but we don't know how long for the time being, therefore I'm not sure if DAC8760 is able to convert in time.

    This is my opinion. How do you consider?

  • 0 in reply to Jingtai
    TI__Mastermind 46290 points

    Jingtai,

    The maximum clock rate of the DAC8760 digital interface is 50MHz and the input frame size is 24-bits or 32-bits depending on whether CRC mode is enabled or not. In either case the digital interface would not be the bottleneck, instead this would be the settling time of the DAC output.

    The datasheet specifies the settling time for a 0V to 10V step size with the output settling to 0.03% FSR as 22us which would be an update rate of about 45kHz. In your actual application perhaps these large steps wouldn't happen or you wouldn't require the output to settle to 0.03% so you might be able to cut off some time associated with small-signal settling time.

    A DAC with sufficient settling time to keep up with 10MHz update rate of the ADC would need to be pretty quick, 100ns or so of settling time. A DAC that fast doesn't usually also have good DC performance, it would usually be a product aimed at AC applications. Having both speed and accuracy to this level is sort of an industry-wide gap.

  • 0 in reply to Kevin Duke
    Genius 4575 points
    It seems that this is not a popular application and there have been no suitable products. I'll consider how test.