AD7745/AD7746

Rev. 0 | Page 16 of 28

CAP SET-UP REGISTER

Address Pointer 0x07, Default Value 0x00

Capacitive channel setup.

Table 11. CAP Set-Up Register Bit Map

Bit

Bit 7

Bit 6

Bit 5

Bit 4

Bit 3

Bit 2

Bit 1

Bit 0

Mnemonic

CAPEN

CIN2

CAPDIFF

-

-

-

-

CAPCHOP

Default

0

0

0

0

0

0

0

0

Table 12.

Bit

Mnemonic

Description

7

CAPEN

CAPEN = 1 enables capacitive channel for single conversion, continuous conversion, or calibration.

6

CIN2

CIN2 = 1 switches the internal multiplexer to the second capacitive input on the AD7746.

5

CAPDIFF

DIFF = 1 sets differential mode on the selected capacitive input.

4-1

-

These bits must be 0 for proper operation.

0

CAPCHOP

The CAPCHOP bit should be set to 0 for the specified capacitive channel performance.

CAPCHOP = 1 approximately doubles the capacitive channel conversion times and slightly improves the

capacitive channel noise performance for the longest conversion times.

VT SET-UP REGISTER

Address Pointer 0x08, Default Value 0x00

Voltage/Temperature channel setup.

Table 13. VT Set-Up Register Bit Map

Bit

Bit 7

Bit 6

Bit 5

Bit 4

Bit 3

Bit 2

Bit 1

Bit 0

Mnemonic

VTEN

VTMD1

VTMD0

EXTREF

-

-

VTSHORT

VTCHOP

Default

0

0

0

0

0

0

0

0

Table 14.

Bit

Mnemonic

Description

7

VTEN

VTEN = 1 enables voltage/temperature channel for single conversion, continuous conversion, or calibration.

Voltage/temperature channel input configuration.

VTMD1

VTMD0

Channel Input

0

0

Internal temperature sensor

0

1

External temperature sensor diode

1

0

6

5

VTMD1

VTMD0

1

1

External voltage input (VIN)

4

EXTREF

EXTREF = 1 selects an external reference voltage connected to REFIN(+), REFIN(–) for the voltage input or the

EXTREF = 0 selects the on-chip internal reference. The internal reference must be used with the internal

temperature sensor for proper operation.

3-2

-

These bits must be 0 for proper operation.

1

VTSHORT

VTSHORT = 1 internally shorts the voltage/temperature channel input for test purposes.

0

VTCHOP = 1

VTCHOP = 1 sets internal chopping on the voltage/temperature channel.

The VTCHOP bit must be set to 1 for the specified voltage/temperature channel performance.