EVAL-AD7795EB datasheet(25/36 Pages) AD

25 / 36 page

AD7794/AD7795

Rev. D | Page 25 of 36

OFFSET REGISTER

RS2, RS1, RS0 = 1, 1, 0; Power-On/Reset = 0x8000

(AD7795), 0x800000 (AD7794))

The offset register is a 16-bit register on the AD7795 and a 24-bit

calibration coefficient for the ADC and its power-on reset value

is 0x8000/0x800000, for the AD7794/AD7795, respectively. The

AD7794/AD7795 each have four offset registers. Channel AIN1

to Channel AIN3 have dedicated offset registers while the

AIN4, AIN5, and AIN6 channels share an offset register. Each

of these registers is a read/write register. The register is used in

conjunction with its associated full-scale register to form a

overwritten if an internal or system zero-scale calibration is

initiated by the user. The AD7794/AD7795 must be placed in

power-down mode or idle mode when writing to the offset

FULL-SCALE REGISTER

RS2, RS1, RS0 = 1, 1, 1; Power-On/Reset = 0x5XXX

(AD7795), 0x5XXX00 (AD7794)

The full-scale register is a 16-bit register on the AD7795 and a

24-bit register on the AD7794. The full-scale register holds the

full-scale calibration coefficient for the ADC. The AD7794/

AD7795 each have four full-scale registers. The AIN1, AIN2,

and AIN3 channels have dedicated full-scale registers, while the

AIN4, AIN5, and AIN6 channels share a register. The full-scale

registers are read/write registers. However, when writing to the

full-scale registers, the ADC must be placed in power-down

mode or idle mode. These registers are configured on power-on

with factory calibrated full-scale calibration coefficients, the

calibration being performed at gain = 1. Therefore, every device

has different default coefficients. The coefficients are different,

depending on whether the internal reference or an external

reference is selected. The default value is automatically

overwritten if an internal or system full-scale calibration is

initiated by the user or the full-scale register is written to.

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