ZHCSEV8D March 2016 – January 2018 ADS131A02 , ADS131A04
PRODUCTION DATA.
The data words follow the status word. The device shifts individual channel data in separate data words. The ADS131A0x converter is 24-bit resolution regardless of the device word length; see Table 7. The output data are truncated to 16 bits when using the 16-bit device word length setting (or when enabling hamming code with a 24-bit device word length setting). The output data are extended to 32 bits with eight zeroes (00000000) added to the least significant bits when using the 32-bit device word length setting (when hamming code is disabled).
Use the device word length (see Table 7) to set the output resolution of the ADS131A0x. When placing the hardware M1 pin in a floating state, the interface operates in 16-bit device word length mode by removing the eight least significant bits. The 16 bits of data per channel are sent in binary twos complement format, MSB first. The size of one code (LSB) is calculated using Equation 8:
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 8 summarizes the ideal output codes for different input signals.
INPUT SIGNAL, VIN
VAINxP - VAINxN |
IDEAL OUTPUT CODE(1) |
---|---|
≥ FS (215 – 1) / 215 | 7FFFh |
FS / 215 | 0001h |
0 | 0000h |
–FS / 215 | FFFFh |
≤ –FS | 8000h |
Pull the M1 pin to IOVDD (through a < 1-kΩ resistor) or GND (through a < 1-kΩ resistor) to set the device either to a 24-bit or 32-bit device word length. In either setting, the ADS131A0x outputs 24 bits of data per channel in binary twos complement format, MSB first. The size of one code (LSB) is calculated using Equation 9:
A positive full-scale input [VIN ≥ (FS – 1 LSB) = (VREF / Gain – 1 LSB)] produces an output code of 7FFFFFh and a negative full-scale input (VIN ≤ –FS = –VREF / Gain) produces an output code of 800000h. The output clips at these codes for signals that exceed full-scale.
Table 9 summarizes the ideal output codes for different input signals.
INPUT SIGNAL, VIN
VAINxP - VAINxN |
IDEAL OUTPUT CODE(1) |
---|---|
≥ FS (223 – 1) / 223 | 7FFFFFh |
FS / 223 | 000001h |
0 | 000000h |
–FS / 223 | FFFFFFh |
≤ –FS | 800000h |