AD7739

Rev. 0 | Page 16 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 digital I/O port on the AD7739.

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

1

0

0

0

0

Bit

Mnemonic

Description

7, 6

P0, P1

When the P0 and P1 pins are configured as outputs, the P0 and P1 bits determine the pins’ output level. 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 will be an input; when reset to 0, the corresponding pin will be an output.

3

RDYFN

This bit is used to control the function of the RDY pin on the 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 will go low only if all

enabled channels have unread data.

2

REDPWR

Reduced Power. If this bit is set to 1, the 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 the AD7739 modulator and digital

filter with other devices in the system.

REVISION REGISTER

8 Bits, Read-Only Register, Address 0x02, Default Value 0x09 + Chip Revision × 0x10

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

x

x

x

1

0

0

1

Bit

Mnemonic

Description

7–4

Chip Revision Code

4-Bit Factory Chip Revision Code

3–0

Chip Generic Code

On the AD7739, these bits will read back as 0x09.

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.