REV. 0

AD7738

–15–

Checksum Register

16 Bits, Read/Write Register, Address 05h

This register is described in the “AD7732/34/38 Checksum Register” Technical Note.

ADC Zero Scale Calibration Register

24 Bits, Read/Write Register, Address 06h, Default Value 800000h

The register holds the ADC Zero-Scale Calibration coefficient. The value in this register is used in conjunction with the value in the

ADC Full-Scale Calibration register and corresponding Channel Zero-Scale and Channel Full-Scale Calibration registers to scale

digitally all channels’ conversion results. The value in this register is updated automatically following the execution of an ADC Zero-

Scale ADC Self-Calibration. Writing to this register is possible in the Idle Mode only. See the calibration description for more details.

ADC Full-Scale Register

24 Bits, Read/Write Register, Address 07h, Default Value 800000h

The register holds the ADC Full-Scale coefficient. The user is advised not to change the default configuration of this register.

Channel Data Registers

16/24 Bits, Read-Only Registers, Address 08h–0Fh, Default Width 16 Bits, Default Value 8000h

These registers contain the most up-to-date conversion results corresponding to each analog input channel. The 16- or 24-bit data

width can be configured by setting the “16/24” bit in the Mode register. The relevant RDY bit in the Channel Status register goes

high when the result is updated. The RDY bit will return low once the Data register reading has begun. The

RDY pin can be configured

to indicate when any channel has unread data or waits until all enabled channels have unread data. If any Channel Data Register read

operation is in progress when the new result is updated, then no update of the Data register occurs. This is to avoid getting corrupted

data. Reading the Status registers can be associated with reading the Data registers in the Dump mode. Reading the Status registers is

always associated with reading the Data registers in the Continuous Read mode. See the digital interface description for more details.

Channel Zero-Scale Calibration Registers

24 Bits, Read/Write Registers, Address 10h–17h, Default Value 800000h

These registers hold the particular channel Zero-Scale Calibration coefficients. The value in these registers is used in conjunction

with the value in the corresponding Channel Full-Scale Calibration register, the ADC Zero-Scale Calibration register, and ADC

Full-Scale Calibration register to scale digitally the particular channel conversion results. The value in this register is updated auto-

matically following the execution of a Channel Zero-Scale System Calibration.

The format of the Channel Zero-Scale Calibration register is a sign bit and 22 bits unsigned value.

Writing this register is possible in the Idle Mode only. See the calibration description for more details.

Channel Full-Scale Calibration Registers

24 Bits, Read/Write Registers, Address 18h–1Fh, Default Value 200000h

These registers hold the particular channel Full-Scale Calibration coefficients. The value in these registers is used in conjunction with

the value in the corresponding Channel Zero-Scale Calibration register, the ADC Zero-Scale Calibration register, and ADC Full

Scale Calibration register to scale digitally the particular channel conversion results. The value in this register is updated automati-

cally following the execution of a Channel Full-Scale System Calibration. Writing this register is possible in the Idle mode only. See

the calibration description for more details.