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ADS8689: Input bandwidth for ADS868x family

Yen Ting Chu
Intellectual 1350 points
Part Number: ADS8689
Other Parts Discussed in Thread: ADS8685, , ADS8681, ADS8860

Team,

My customer is asking the input bandwidth for ADS868x family. ADS8681, ADS8685 and ADS8689 have different sampling rate and they should share different input bandwidth. However, according to the datasheet, the three devices share the same input bandwidth frequency for -3dB (15kHz) and -0.1dB (2.5kHz). Would you please elaborate more on this question?

If my customer is would like to sample 0Hz to 50kHz, does ADS8689 fit their design need? If not, would you please advice other solution? Thanks for your comment.

Best regards,

Andy Chu

  • 0
    TI__Guru 62475 points

    Hello Andy,

    The ADS868x devices you've noted do have different sampling rates.  However, as you can see in the block diagram for each of the devices there is a 2nd order LPF between the input analog front end and the ADC which limits the input signal bandwidth to the values you've noted.  

    The ADS8860 and similar families of devices will work for your 0-50kHz input signal bandwidth application but will require an input driver circuit since the AFE is not integrated into this device. 

  • 0 in reply to Collin Wells
    TI__Intellectual 1350 points

    Collin,

    Would you please propose ADC solution based on the below spec? There is no spec filter to filter out the bipolar input voltage. I would be hard to filter out the right ADC device.

    1.       Sample Rate(max)：52 kS/S～100 kS/S
    2.       ADC Resolution：16 bits
    3.       Dynamic Range：100dB
    4.       Industrial grade device need
    5.       Single channel or quad channel
    6.       Isolation is not needed
    7.       SPI interface will be great
    8.       support +/-10V input voltage

    Thank you

    Best regards,

    Andy Chu

  • 0 in reply to Yen Ting Chu
    TI__Guru 62475 points

    Hi Andy,

    Does the application still require the 50kHz input bandwidth?  If so, take a look at the following devices:

    16-Bit, 250-kSPS, 1-Ch SAR ADC with programmable (±10/±5/±3.3V) input ranges and SPI interface:  
    http://www.ti.com/product/ADS8509

    Low-Power 16-Bit 200kSPS ±10V Bipolar Input SAR ADC With S/P Interface:
    http://www.ti.com/product/ADS8517

    16-Bit 8-Channel Simultaneous-Sampling Bipolar-Input SAR ADC:
    http://www.ti.com/product/ADS8568