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High-precision DAC (=>20 bits)

Camilla Westrin
Prodigy 20 points

Other Parts Discussed in Thread: DAC9881, DAC1220

Hello!

I have need of a high precision DAC for laser servo control. This DAC needs to have a resolution of about 20 bits (more wouldn't hurt) and should be able to run at at least 10 KSPS.

I posted this question in http://e2e.ti.com/support/data_converters/precision_data_converters/f/73/p/2928/846754.aspx#846754 a few days ago. Sorry about the cross-post, but I was unsure of how an "answered" thread in which someone posts a follow up question is handled on this forum. Perhaps the lack of answer was due to me using an old thread? (or possibly just because it was not long ago I asked the question, sorry about my lack of patience too... ;))

Anyhow, the DAC recommended in that thread (PCM1704) is discontinued, can I use the DAC recommended as replacement, or is there some other DAc which will be able to do the job better?

Thanks!

  • 0
    TI__Mastermind 46290 points

    Camilla,

    Whenever you post in a thread the only people that will be notified of it are people participating in that thread. When you post a new thread to the forum everyone subscribed to the forum will be notified. Mr. Hartl may be aware of the question and just hasn't responded to you yet there (he's typically found on the Audio forum).

    The devices discussed in the thread you referenced are audio codecs. So, if you want to investigate those DACs further you might want to post a question in the audio forum where the experts for those devices dwell. That forum is here.

    The devices supported in this forum are typically String DACs or R-2R DACs, rather than the delta-sigma architecture discussed in the thread you pointed to. The DAC9881 is the highest resolution R-2R DAC we offer right now. Delta-sigma DACs are usually created for audio applications but there are a few delta-sigma DACs that have come out of our precision group. The highest resolution of these devices is the DAC1220. The DAC9881 will require that you sacrifice resolution, but you will gain much improved settling time over the DAC1220 (1.8ms vs 5us). 

    I saw that you asked a question about interfacing DAC devices, I think in general, to an FPGA and I do not think you'll really encounter any problems. The DAC1220 uses byte frames to transfer commands followed by data and features internal registers while the DAC9881 uses a 24 bit-wide frame and has no internal registers. Features for the DAC9881 are simply controlled by pins on the device.

    If you have any further questions or need better clarification on anything let me know.