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TMS320F28388D: TMS320F28388D Differential ADC 16-bit input buffer

Jennifer Stander
Intellectual 510 points
Part Number: TMS320F28388D


Hi,

I am planning on using the TMS320F28388D ADC in 16-bit differential input mode with a Vref of 2.5V. I notice with other ADCs sometimes I see that there are mini low pass RC filter in between the buffer and the ADC input. From the specification, I am assuming that I want to keep the Rs and Cp to a minimimum to maximize settling time. Does TI recommend just connecting the output of the differential buffer directly to the ADC input or should I put an option to populate an RC filter?

Thanks,

Jennifer

  • 0
    TI__Mastermind 38830 points

    Hi Jennifer,

    Minimizing the external Rs and Cp would actually maximize the throughput of the ADC by minimizing the settling time requirement of the sampling capacitor.  By using a differential buffer to condition the signal, you are actually isolating the external Rs and Cp from the ADC input and allows you more freedom in selecting external Rs and Cp values for the low pass filter without worrying about how this will affect acquisition time.  The output of the buffer will have drive strength allow for minimum acquisition time for the sampling capacitor in the ADC core.  We do not recommend populating RC filter after the buffer.  Just connect the buffer output directly to the ADC input pins.

    Best regards,

    Joseph