SBAS894A April 2018 – October 2018 ADS112C04
The device provides 16 bits of data in binary two's complement format. Use Equation 8 to calculate the size of one code (LSB).
A positive full-scale input [VIN ≥ (+FS – 1 LSB) = (VREF / Gain – 1 LSB)] produces an output code of 7FFFh and a negative full scale input (VIN ≤ –FS = –VREF / Gain) produces an output code of 8000h. The output clips at these codes for signals that exceed full-scale.
Table 15 summarizes the ideal output codes for different input signals.
VIN = VAINP – VAINN
|IDEAL OUTPUT CODE(1)|
|≥ FS (215 – 1) / 215||7FFFh|
|FS / 215||0001h|
|–FS / 215||FFFFh|
Figure 56 shows the mapping of the analog input signal to the output codes.
Single-ended signal measurements, where VAINN = 0 V and VAINP = 0 V to +FS, only use the positive code range from 0000h to 7FFFh. However, because of device offset, the ADS112C04 can still output negative codes when VAINP is close to 0 V.