Datasheet

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.