• State Resolved
  • Locked Locked
  • Replies 3 replies
  • Subscribers 48 subscribers
  • Views 1119 views
  • Users 0 members are here
Support feedback
Options
Options
Related

This thread has been locked.

If you have a related question, please click the "Ask a related question" button in the top right corner. The newly created question will be automatically linked to this question.

DAC8760 Specification for converting Unit %FSR to dB Scale

Jin Kyung Han
Expert 1520 points

Other Parts Discussed in Thread: DAC8760

Hello

As see the attatched data sheet LTC1592 and DAC8760.

I am reviewing specification of DAC to replace LTC1592 with DAC8760 which is going to be used for PLC(Programmable Logic Control).

However It is difficult to understand specification between them because the Unit is different such as %FSR  Vs  +/-dB.

I would like to know how to convert the Unit from %FSR to dB scale and have example about INL conversion.

Let me know how to convert unit and Calculation procedure.

Thanks and Best Regards

  • 0
    TI__Mastermind 46290 points
    Jin,

    Which specification are you comparing that is offered in % FSR in one datasheet but dB in the other? While both units are used to represent ratios, it's not very usual that they're interchangeably used for the same specification across industry. I looked through both datasheets and couldn't figure out which specifications you're comparing.

    Conversion from %FSR for the INL specifications in the DAC8760 datasheet to LSBs specified in the LTC datasheet is fairly straightforward but keep in mind the INL specification depends on which range you're looking at for the DAC8760 since the specifications change from range to range. It is simply INL(%FSR)*2^(resolution). So for instance the INL for the voltage output in the DAC8760 datasheet is 0.022% FSR so the value in LSBs is 0.022%*65536 = 15.72 LSBs.

    Comparing these two devices directly isn't really a proper comparison. The LTC device is a multiplying DAC with a current output. This isn't the same kind of current output that is featured on the DAC8760 - the LTC part is simply a resistor ladder that produces a current. That means when a load is placed on the output of the LTC device, the current output will change. For that reason a multiplying DAC isn't typically used as a current output, but rather as a voltage output when a transimpedance amplifier on it's output stage to provide isolation from the load. From there, the LTC device would still have to provide another gain stage to provide the bipolar voltage output ranges that the DAC8760 provides and a high-side voltage-to-current converter to deliver the current outputs in order to be comparable devices.
  • 0 in reply to Kevin Duke
    Expert 1520 points

    Kevin

    I have already knew the LTC1592 need extenal OP AMP for driving 4-20mA, On the contrary DAC8760 has OP AMP driver.

    Furthemore, Functionally DAC8760 is superior than LTC1592 so that I am going to use DAC8760 for PLC.

    Finallly Your answer for my question is helpful to understand DAC specification.

    Thanks and Best Regards 

  • 0 in reply to Kevin Duke
    Expert 1520 points
    Kevin

    I have already knew the LTC1592 need extenal OP AMP for driving 4-20mA, On the contrary DAC8760 has OP AMP driver.

    Furthemore, Functionally DAC8760 is superior than LTC1592 so that I am going to use DAC8760 for PLC.

    Finallly Your answer for my question is helpful to understand DAC specification.

    Thanks and Best Regards