AD7734

Rev. 0 | Page 18 of 32

Channel Zero-Scale Calibration Registers

24 Bits, Read/Write Registers, Address 10h–13h, 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 the ADC full-scale register to digitally scale the

particular channel conversion results. The value in this register

is updated automatically 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 section for

more details).

Channel Full-Scale Calibration Registers

24 Bits, Read/Write Registers, Address 18h–1Bh, 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

the ADC full-scale register to digitally scale the particular

channel conversion results. The value in this register is updated

automatically following the execution of a channel full-scale

system calibration. Writing this register is possible in the idle

mode only (see the Calibration section for more details).

Channel Status Registers

8 Bits, Read-Only Register, Address 20h–23h, Default Value 20h × Channel Number

These registers contain individual channel status information and some general AD7734 status information. 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 section for more details).

Bit

Bit 7

Bit 6

Bit 5

Bit 4

Bit 3

Bit 2

Bit 1

Bit 0

Mnemonic

0

CH1

CH0

0/P0

RDY/P1

NOREF

SIGN

OVR

Default

Channel Number

0

0

0

0

0

Bit

Mnemonic

Description

7–5

CH1–CH0

These bits reflect the channel number. This can be used for current channel identification and easier operation

of the dump mode and continuous read mode.

4

0/P0

When the status option bit of the corresponding channel setup register is reset to 0, this bit is read as a zero.

When the status option bit is set to 1, this bit reflects the state of the P0 pin, whether it is configured as an

input or an output.

3

RDY/P1

When the status option bit of the corresponding channel setup register is reset to 0, this bit reflects the

selected channel RDY bit in the ADC status register. When the status option bit is set to 1, this bit reflects the

state of the P1 pin, whether it is configured as an input or an output.

2

NOREF

This bit indicates the reference input status. If the voltage between the REFIN(+) and REFIN(–) pins is less than

NOREF, the trigger voltage and a conversion is executed, then the NOREF bit goes to 1.

1

SIGN

The voltage polarity at the analog input. It will be 0 for a positive voltage and 1 for a negative voltage.

0

OVR

This bit reflects either the overrange or the underrange on the analog input. The bit is set to 1 when the

analog input voltage goes over or under the nominal voltage range (see the Analog Input’s Extended Voltage

Range section).