SBAS813 June 2018 ADS8688AT
PRODUCTION DATA.
The ADS8688AT is a multichannel device that supports single-ended, bipolar, and unipolar input ranges on all input channels. The output of the device is in straight binary format for both bipolar and unipolar input ranges. The format for the output codes is the same across all analog channels.
Figure 81 shows the ideal transfer characteristic for each ADC channel for all input ranges. The full-scale range (FSR) for each input signal is equal to the difference between the positive full-scale (PFS) input voltage and the negative full-scale (NFS) input voltage. The LSB size is equal to FSR / 216 = FSR / 65536 because the resolution of the ADC is 16 bits. For a reference voltage of VREF = 4.096 V, Table 4 lists the LSB values corresponding to the different input ranges.
INPUT RANGE (V) | POSITIVE FULL-SCALE (V) | NEGATIVE FULL-SCALE (V) | FULL-SCALE RANGE (V) | LSB (µV) |
---|---|---|---|---|
±2.5 × VREF | 10.24 | –10.24 | 20.48 | 312.50 |
±1.25 × VREF | 5.12 | –5.12 | 10.24 | 156.25 |
±0.625 × VREF | 2.56 | –2.56 | 5.12 | 78.125 |
±0.3125 × VREF | 1.28 | –1.28 | 2.56 | 39.0625 |
±0.15625 × VREF | 0.64 | –0.64 | 1.28 | 19.53125 |
0 to 2.5 × VREF | 10.24 | 0 | 10.24 | 156.25 |
0 to 1.25 × VREF | 5.12 | 0 | 5.12 | 78.125 |
0 to 0.625 × VREF | 2.56 | 0 | 2.56 | 39.0625 |
0 to 0.3125 × VREF | 1.28 | 0 | 1.28 | 19.53125 |