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ADS930E interfacing with CCD output

Krunal Patel
Prodigy 80 points

Other Parts Discussed in Thread: ADS930

Hi,

I have a linear CCD  module and it is interfaced with ADS930E high speed ADC.

But I am not getting the reliable reading.

For 1V at IN+ pin, ADC digital output is 0 and for 2V at IN+ pin ADC digital output is 255. But, for intermidiate value (between 1V and 2V) at IN+ pin ADC digital output  is random.

I have searched for reference circuit on TI portal but no luck.

Please let me have any reference circuit of ADS930e so that I can verify my hardware side design.

Also some query, I am using ADS930E in single ended mode, IN- pin is shorted with CM pin.

So what would be the analog reference voltage for ADC chip to calculate ADC resolution?

Or it is fixed between 1V and  2V, as specified in the datasheet. i.e. ADC resolution is = (2v-1v) / 255.

 

Thanks n regards.

 

  • 0
    TI__Mastermind 29220 points

    Hi,

    We do offer an evaluation board for the ADS930, as may be seen at http://focus.ti.com/docs/toolsw/folders/print/dem-ads9xxe.html

    This is one of our older EVMs and comes with a printed copy of a User Manual in the box, but the User Guide has not been put on the web with a literature number.  I do have a pdf of the User Guide, however.  Please see attached.  The User Guide shows the schematics of the EVM and is the only reference design we have.

    If the output appears random with some input voltage witthin the full scale range, are you checking the sample data value relative to the timing specified relative to the sample clock?  This device does not output an output clock with the sample data as our newer ADC devices do, but rather the sample clock that is input to the ADC is also to be used as the clock to latch the sample data from the ADC.  Also, it is common for the least significant bit or two to appear somewhat random due to noise.

    The reference voltages for REFT and REFB as seen on the pins LpBy adn LnBy should be as described in the datasheet, 1.75V and 1.25V.  For a full scale range of 1V, the resolution of the device will be as you suggest: (2V-1V)/255 or 3.92mV.

    Regards,

    Richard P.

    ADS9xxE_DEM.pdf