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DAC34H84EVM: TSW1400

Dean Vieau1
Prodigy 40 points
Part Number: DAC34H84EVM

DAC34H84evm with TSW1400 setup w/ output of data sampled at 781Khz - .csv pile 'playback'

I want to play back .csv data that was captured at a sample rate of 781khz with the DAC34H84evm on all 4 DAC channels:

Questions: From previous forum discussions it appears that the output transformer 'on board' will not pass lower frequencies (say <~75khz). Where is the information regarding the current transformer so that I can design/obtain a transformer more suited for the frequency range of ~2Khz to ~800khz?

Also, will the DAC actually work down to these low frequencies (disregarding the transformer issue)?

Do you have some guidelines for setting up for these low frequency ranges?

What about the 5pf output cap relating to the DAC output - Is there a way to make the DAC output characteristics more appropriate for use at <1Mhz???

Thank you,

DMV

  • 0
    TI__Guru 66104 points

    Hello Dean,

    The information regarding the EVM schematic and also the BOM for the output transformer is in the design file of the EVM:

    you may refer to the Mini-circuits datasheet of ADT4-1T for the frequency response. You may potentially contact them for support to see if they have a pin compatible balun/transformer that can work per the frequency specification of your need. For low frequency range, the magnetic response behaves different and requires larger physical size of balun, perhaps. Contact them for details.

    The DAC is designed to work at DC.

    for DC coupled interface, you may refer to the information in the following TIDA to understanding the output structure and other potential ideas of DC coupling for your application:

    http://www.ti.com/lit/ug/slua647a/slua647a.pdf

    There are various topics regarding DC coupled interface on E2E website. you may do some search. For example:

    https://e2e.ti.com/support/data-converters/f/73/p/656058/2412253#2412253

    you will need to consider the DC level accepted by your signal chain circuit on the downstream.

    The 5pF cap is a typical parallel output capacitance. It is parallelly modeled parasitic of the die and the package. The DAC itself will work as low as 1MHz, and should roll-off at higher frequencies.

    -Kang