Datasheet

ManualsBrandsANALOG DEVICES ManualsData collecting ICsData acquisition IC - ADC 24 Bit TSSOP 16

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 V

monitor

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

monitor.

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.