8.5.2 Calibration Commands

Calibration commands may be sent to the ADS1282-SP to calibrate the conversion data. The values of the offset and gain calibration registers are internally written to perform calibration. The appropriate input signals must be applied to the ADS1282-SP inputs before sending the commands. Use slower data rates to achieve more consistent calibration results; this effect is a byproduct of the lower noise that these data rates provide. Also, if calibrating at power-on, be sure the reference voltage is fully settled.

Figure 61 shows the calibration command sequence. After the analog input voltage (and reference) have stabilized, send the Stop Data Continuous command followed by the SYNC and Read Data Continuous commands. 64 data periods later, DRDY goes low. After DRDY goes low, send the Stop Data Continuous, then the Calibrate command followed by the Read Data Continuous command. After 16 data periods, calibration is complete and conversion data may be read at this time. The SYNC input must remain high during the calibration sequence.

The calibration commands apply to specific PGA settings. If the PGA is changed, recalibration is necessary. Calibration is bypassed in the sinc filter mode.