AD7854/AD7854L

–10–

REV. B

STATUS REGISTER

The arrangement of the status register is shown below. The status register is a read-only register and contains 16 bits of data. The

status register is selected by writing to the control register and putting two 1s in RDSLT1 and RDSLT0. The function of the bits in

the status register are described below. The power-up status of all bits is 0.

START

READ STATUS REGISTER

WRITE TO CONTROL REGISTER

SETTING RDSLT0 = RDSLT1 = 1

Figure 4. Flowchart for Reading the Status Register

MSB

ZERO

ZERO

ZERO

ZERO

ZERO

ZERO

PMGT1

PMGT0

ONE

ONE

AMODE

BUSY

CALMD

CALSLT1

CALSLT0

STCAL

LSB

Status Register Bit Function Description

Bit

Mnemonic

Comment

15

ZERO

These six bits are always 0.

14

ZERO

13

ZERO

12

ZERO

11

ZERO

10

ZERO

9

PMGT1

Power Management Bits. These bits will indicate if the part is in a power-down mode or not. See Table VI

8

PMGT0

in Power-Down Section for description.

7

ONE

Both these bits are always 1.

6

ONE

5

AMODE

Analog Mode Bit. When this bit is a 0, the device is set up for the unipolar analog input range. When this

bit is a 1, the device is set up for the bipolar analog input range.

4

BUSY

Conversion/Calibration Busy Bit. When this bit is 1, this indicates that there is a conversion or calibration

in progress. When this bit is 0, there is no conversion or calibration in progress.

3

CALMD

Calibration Mode Bit. A 0 in this bit indicates a self-calibration is selected, and a 1 in this bit indicates a

system calibration is selected (see Table III).

2

CALSLT1

Calibration Selection Bits and Start Calibration Bit. The STCAL bit is read as a 1 if a calibration is in

1

CALSLT0

progress and as a 0 if there is no calibration in progress. The CALSLT1 and CALSLT0 bits indicate

0

STCAL

which of the calibration registers are addressed for reading and writing (see section on the Calibration

Registers for more details).