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ADS1158 Specification Errors?

Scott Kerstein
Expert 1395 points

Other Parts Discussed in Thread: REF3125, ADS1158

With regards to page 42 & Figure 54 of the ADS1158 specification.  Note the hookup to the reference REF5040 and buffer (although the text says REF3125).  In Figure 54, it shows a 100uF capacitance on the reference output—Is this a misprint?  Is this supposed to be 10uF?  100uF would be a fairly large capacitor value.  

Another issue from page 42 & Figure 54—The text says “The 2.5V reference 3125, is filtered and buffered to provide a low-noise reference input to the ADC.”, but the reference shown in Figure 54 is a REF5040 4.096V reference.  Is this an error and it should be 2.5V, or just an example using 4.096Vref?

Thanks, in advance.

Scott

  • 0
    TI__Genius 14317 points

    Scott,

    The 100 uF cap in parallel w/.1 uF is part of the DC single pole filter for the reference. For an optimum DC filter, these values are correct as specified. The REF5040 in Fig. 54 is correct and matches the Typical conditions specified in the Electrical Charactistics table. The text referring to the REF3125 and Vref = 2.5 V is in error but that reference could be used as well since its within the allowed range specified in the Electrical Characteristics table. Note that the AIN and ADCINP - ADCINN voltage maximums are per the Electrical Characteristics Table.