AD7705/AD7706

Rev. C | Page 18 of 44

Table 16. Operating Mode Options

MD1

MD0

Operating Mode

0

0

Normal Mode. In this mode, the device performs normal conversions.

0

1

Self-Calibration. This activates self-calibration on the channel selected by CH1 and CH0 of the communication register. This

is a one-step calibration sequence. When the sequence is complete, the part returns to normal mode, with both MD1 and

MD0 returning to 0. The DRDY output or bit goes high when calibration is initiated, and returns low when self-calibration is

complete and a new valid word is available in the data register. The zero-scale calibration is performed at the selected gain

on internally shorted (zeroed) inputs, and the full-scale calibration is performed at the selected gain on an internally

1

0

Zero-Scale System Calibration. This activates zero-scale system calibration on the channel selected by CH1 and CH0 of the

communication register. Calibration is performed at the selected gain on the input voltage provided at the analog input

during this calibration sequence. This input voltage should remain stable for the duration of the calibration. The DRDY

output or bit goes high when calibration is initiated, and returns low when zero-scale calibration is complete and a new

valid word is available in the data register. At the end of the calibration, the part returns to normal mode, with both MD1

and MD0 returning to 0.

1

1

Full-Scale System Calibration. This activates full-scale system calibration on the selected input channel. Calibration is

performed at the selected gain on the input voltage provided at the analog input during this calibration sequence. This

input voltage should remain stable for the duration of the calibration. The DRDY output or bit goes high when calibration is

initiated, and returns low when full-scale calibration is complete and a new valid word is available in the data register. At the

end of the calibration, the part returns to normal mode, with both MD1 and MD0 returning to 0.

Table 17. Gain Selection

G2

G1

G0

Gain Setting

0

0

0

1

0

0

1

2

0

1

0

4

0

1

1

8

1

0

0

16

1

0

1

32

1

1

0

64

1

1

1

128