Data Sheet

AD7734

Rev. A | Page 19 of 32

CHANNEL SETUP REGISTERS

8 Bits, Read/Write Register, Address 28h–2Bh, Default Value 00h

These registers are used to configure the selected channel, to configure its input voltage range, and to set up the corresponding channel

status register.

Bit

Bit 7

Bit 6

Bit 5

Bit 4

Bit 3

Bit 2

Bit 1

Bit 0

Mnemonic

0

0

0

Stat OPT

ENABLE

0

RNG1

RNG0

Default

0

0

0

0

0

0

0

0

Bit

Mnemonic

Description

7–5

0

These bits must be 0 for proper operation.

4

Stat OPT

Status Option. When this bit is set to 1, the P0 and P1 bits in the channel status register will reflect the state of

the P0 and P1 pins. When this bit is reset to 0, the RDY bit in the channel status register will reflect the channel

corresponding to the RDY bit in the ADC status register.

3

ENABLE

Channel Enable. Set this bit to 1 to enable the channel in the continuous conversion mode. A single conversion

will take place regardless of this bit’s value.

2

0

This bit must be 0 for proper operation.

1–0

RNG1–RNG0

This is the channel input voltage range (see Table 15).

TABLE 15.

RNG1

RNG0

Nominal Input Voltage Range

0

0

±10 V

0

1

0 V to +10 V

1

0

±5 V

1

1

0 V to +5 V

CHANNEL CONVERSION TIME REGISTERS

8 Bits, Read/Write Register, Address 30h–33h, Default Value 91h

The conversion time registers enable or disable chopping and configure the digital filter for a particular channel. This register value

affects the conversion time, frequency response, and noise performance of the ADC.

Bit

Bit 7

Bit 6

Bit 5

Bit 4

Bit 3

Bit 2

Bit 1

Bit 0

Mnemonic

CHOP

FW (7-Bit Filter Word)

Default

1

11h

Bit

Mnemonic

Description

7

CHOP

Chopping Enable Bit. Set to 1 to apply chopping mode for a particular channel.

6–0

FW

CHOP = 1, single conversion or continuous conversion with one channel enabled.

Conversion Time (µs) = (FW × 128 + 248)/MCLK Frequency (MHz), the FW range is 2 to 127.

CHOP = 1, continuous conversion with two or more channels enabled.

Conversion Time (µs) = (FW × 128 + 249)/MCLK Frequency (MHz), the FW range is 2 to 127.

CHOP = 0, single conversion or continuous conversion with one channel enabled.

Conversion Time (µs) = (FW × 64 + 206)/MCLK Frequency (MHz), the FW range is 3 to 127.

CHOP = 0, continuous conversion with two or more channels enabled.

Conversion Time (µs) = (FW × 64 + 207)/MCLK Frequency (MHz), the FW range is 3 to 127.