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Bypass DDC with ADC12J2700EVM and TSW14J56EVM

Roy Sivley
Prodigy 20 points
Other Parts Discussed in Thread: ADC12J2700, ADC12J2700EVM, ADC12J4000

Hi,

I am interested in using the ADC12J2700EVM and TSW14J56EVM to evaluate the ADC12J2700 in bypass mode.  After reading through the user guides and data sheets, I still have a few questions:

1) Does ADC12J2700EVM support the bypass mode of operation?

2) Does TSW14J56EVM support the link parameters used in bypass mode?  The ADC12J2700 data sheet says bypass mode uses LFMS=8885, but the TSW14J56EVM user guide says it can only support 1-4 octets per frame.

3) How many contiguous samples can be captured with these boards and the HSDC Pro software?  For 32 Gb of DDR3 memory and 12-bit samples, I would assume I could collect 2.67 G of contiguous samples (or 0.988 s @ 2.7 GSPS).  Is this correct, or are more bits used to actually store the samples?

Thanks for your help!

Roy

  • 0
    TI__Mastermind 43930 points

    Hi Roy

    1) Yes. The ADC12J2700EVM supports bypass mode and all decimation settings. In High Speed Data Converter Pro select "ADC12J4000_BYPASS" for the ADC capture mode.

    2) The TSW14J56EVM firmware is able to work with the ADC12J2700 bypass mode data format by using a different combination of F and K. Since the firmware doesn't support F>4 a larger K value is used to compensate. When data is saved to DRAM it saves all octets in the data frame/stream rather than pulling out the 12 bit values and discarding the Tail bits. The Tail bit overhead reduces the maximum number of samples that can be saved.

    3) I checked a TSW14J56EVM Rev. D board and found that the maximum possible capture setting in bypass mode is 2147483648. If a larger Data Capture setting is entered it is forced down to that maximum value. The earlier TSW14J56EVM Rev B boards have less memory and a lower maximum capture depth.

    Best regards,

    Jim B