Datasheet
Data Sheet AD7739
Rev. A | Page 13 of 32
REGISTER DESCRIPTIONS
Table 11. Register Summary
Addr Dir Bit 7 Bit 6 Bit 5 Bit 4 Bit 3 Bit 2 Bit 1 Bit 0
Register (hex) Default Value
Communications
0x00 W
0 R/
W
6-bit register address
I/O Port
0x01 R/W
P0 P1 P0 DIR P1 DIR RDYFN REDPWR 0 Sync
P0 pin P1 pin 1 1 0 0 0 0
Revision
0x02 R
Chip revision code Chip generic code
x x x x 1 0 0 1
Test
0x03 R/W
24-bit manufacturing test register
ADC Status
0x04 R
RDY7
RDY6
RDY5
RDY4
RDY3
RDY2
RDY1
RDY0
0 0 0 0 0 0 0 0
Checksum
0x05 R/W
16-bit checksum register
ADC Zero-Scale Calibration
0x06 R/W
24-bit ADC zero-scale calibration register
0x80 0000
ADC Full-Scale Calibration
0x07 R/W
24-bit ADC full-scale register
0x80 0000
Channel Data
1
0x08 to
0x0F
R
16-/24-bit data registers
0x8000
Channel Zero-Scale
Calibration
1
0x10 to
0x17
R/W
24-bit channel zero-scale calibration registers
0x80 0000
Channel Full-Scale
Calibration
1
0x18 to
0x1F
R/W
24-bit channel full-scale calibration registers
0x20 0000
Channel Status
1
0x20 to
0x27
R
CH2 CH1 CH0 0/P0 RDY/P1 NOREF Sign OVR
Channel number 0 0 0 0 0
Channel Setup
1
0x28 to
0x2F
R/W
BUFOFF COM1 COM0 Stat OPT Enable RNG2 RNG1 RNG0
0 0 0 0 0 0 0 0
Channel Conversion Time
1
0x30 to
0x37
R/W
Chop FW (7-bit filter word)
1 0x11
Mode
2
0x38 to
0x3F
R/W
MD2 MD1 MD0 CLKDIS Dump Cont RD 24/16 bit Clamp
0 0 0 0 0 0 0 0
1
The three LSBs of the register address, that is, Bit 2, Bit 1, and Bit 0 in the communications register, specify the channel number of the register being accessed.
2
The AD7739 has only one mode register, although the mode register can be accessed in one of eight address locations. The address used to write the mode register
specifies the ADC channel on which the mode is applied. Only Address 0x38 must be used for reading from the mode register.
Table 12. Operational Mode Summary
MD2
MD1
MD0
Mode
0 0 0 Idle
0 0 1 Continuous conversion
0 1 0 Single conversion
0 1 1 Power-down (standby)
1 0 0 ADC zero-scale self-calibration
1 0 1 ADC full-scale self-calibration (for 2.5 V)
1 1 0 Channel zero-scale system calibration
1 1 1 Channel full-scale system calibration
Table 13. Input Range Summary
RNG2 RNG1 RNG0 Nominal Input Voltage Range
1 0 0 ±2.5 V
1
0
1
+2.5 V
0 0 0 ±1.25 V
0 0 1 +1.25 V
0 1 0 ±0.625 V
0 1 1 +0.625 V