SBAS559A May 2022 – December 2022 ADS1285
PRODUCTION DATA
Offset correction is by a 24-bit word consisting of three 8-bit registers (high address is the MSB). The offset value is left-justified to align to the 32-bit data. The offset value is 2's-complement coding with a maximum positive value of 7FFFFFh and a maximum negative value of 800000h. OFFSET is subtracted from the conversion data; see Table 8-8. Offset error is corrected by the offset calibration command with the input-short multiplexer option, or by collecting shorted-input ADC data and writing the value to the registers.
Although the offset correction range is from –FS to +FS, the sum of offset and gain correction must not exceed 106% of the uncalibrated range.
When the high-pass filter is enabled, offset correction is disabled. The offset value is used instead as a starting value to shorten the high-pass filter settling time. To reload the offset value to the HPF, disable and re-enable the high-pass filter. See the Section 8.3.6.4 section for more details.
OFFSET[31:0] | CALIBRATED OUTPUT CODE (1) |
---|---|
00007Fh | FFFF8100h |
000000h | 00000000h |
FFFF7Fh | 00008100h |