Data Sheet
AD7739
Rev. A | Page 15 of 32
I/O PORT REGISTER
8 Bits, Read/Write Register, Address 0x01,
Default Value 0x30 + Digital Input Value × 0x40
The bits in this register are used to configure and access the
REVISION REGISTER
8 Bits, Read-Only Register, Address 0x02,
Default Value 0x09 + Chip Revision × 0x10
This register contains the 4-bit revision code and the 4-bit
register can be used to correctly identify the ADC, or as a check
to ensure that serial communication is working correctly.
TEST REGISTER
24 Bits, Read/Write Register, Address 0x03
This register is used for testing the part in the manufacturing
process. The user must not change the default configuration of
this register.
ADC STATUS REGISTER
8 Bits, Read-Only Register, Address 0x04, Default Value 0x00
In conversion modes, the register bits reflect the individual
channel status. When a conversion is complete, the corresponding
channel data register is updated and the corresponding RDY bit
is set to 1. When the channel data register is read, the corre-
sponding bit is reset to 0. The bit is reset to 0 also when no read
operation has taken place and the result of the next conversion
is being updated to the channel data register. Writing to the
mode register resets all the bits to 0.
In calibration modes, all the register bits are reset to 0 while a
calibration is in progress; all the register bits are set to 1 when
the calibration is complete.
The RDY pin output is related to the content of the ADC status
register as defined by the RDYFN bit in the I/O port register.
The RDY0 bit corresponds to Channel 0, the RDY1 bit
Table 16. I/O Port Register Bits
Bit
Bit 7
Bit 6
Bit 5
Bit 4
Bit 3
Bit 2
Bit 1
Bit 0
Mnemonic
P0
P1
P0 DIR
P1 DIR
RDYFN
REDPWR
0
Sync
Default
P0 pin
P1 pin
1
0
Table 17. I/O Port Register Bit Descriptions
Bit
Mnemonic
Description
7, 6
P0, P1
When the P0 and P1 pins are configured as outputs, the P0 and P1 bits determine the output level of the pin.
When the P0 and P1 pins are configured as inputs, the P0 and P1 bits reflect the current input level on the pins.
5, 4
P0 DIR, P1 DIR
These bits determine whether the P0 and P1 pins are configured as inputs or outputs. When set to 1, the
corresponding pin is an input; when reset to 0, the corresponding pin is an output.
3
RDYFN
This bit is used to control the function of the RDY pin on t
he AD7739. When this bit is reset to 0, the RDY pin
goes low when any channel has unread data. When this bit is set to 1, the RDY pin goes low only if all enabled
channels have unread data.
2
REDPWR
Reduced power. If this bit is set to 1, th
e AD7739 works in the reduced power mode. The maximum MCLK
frequency is limited to 4 MHz in the reduced power mode.
1
0
This bit must be 0 for proper operation.
0
Sync
This bit enables the SYNC pin function. By default, this bit is 0 and SYNC/P1 can be used as a digital I/O pin.
When the sync bit is set to 1, the SYNC pin can be used to synchronize th
e AD7739 modulator and digital filter
with other devices in the system.
Table 18. Revision Register Bits
Bit
Bit 7
Bit 6
Bit 5
Bit 4
Bit 3
Bit 2
Bit 1
Bit 0
Mnemonic
Chip revision code
Chip generic code
Default
X
1
0
1
Table 19. Revision Register Bit Descriptions
Bit
Mnemonic
Description
7 to 4
Chip revision code
4-bit factory chip revision code
3 to 0
Chip generic code
Table 20. ADC Status Register Bits
Bit
Bit 7
Bit 6
Bit 5
Bit 4
Bit 3
Bit 2
Bit 1
Bit 0
Mnemonic
RDY7
RDY6
RDY5
RDY4
RDY3
RDY2
RDY1
RDY0
Default
0