AD7732 Analog Devices, AD7732 Datasheet - Page 25

• Manufacturer Part Number: AD7732
• Manufacturer: Analog Devices

Specifications of AD7732

• Resolution (bits): 24bit
• # Chan: 2
• Sample Rate: 3.05MSPS
• Interface: Ser,SPI
• Analog Input Type: Diff-Bip,Diff-Uni
• Ain Range: Bip 10V,Bip 5.0V,Uni 10V,Uni 5.0V
• Adc Architecture: Sigma-Delta
• Pkg Type: SOP

Continuous Read (Continuous Conversion) Mode
When the Cont RD bit in the mode register is set, the first write
of 48h to the communications register starts the continuous
read mode. As shown in Figure 22, subsequent accesses to the
part sequentially read the channel status and data registers of
the last completed conversion without any further configuration
of the communications register being required.
Note that the continuous conversion bit in the mode register
should be set when entering the continuous read mode.
Note that the continuous read mode is a dump mode reading of
the channel status and data registers regardless of the dump bit
value. Use the channel bits in the channel status register to
check/recognize that channel data is actually being shifted out.
Note that the last completed conversion result is being read.
Therefore the RDYFN bit in the I/O port register should be 0
DOUT
SCLK
RDY
CS
DIN
INTERFACE
INTERFACE
SERIAL
SERIAL
RDY
RDY
REGISTER
CONTINUOUS
CONVERSION
CONTINUOUS
CONVERSION
COMM.
WRITE
38h
START
START
REGISTER
CH0 CONVERSION
CH0 CONVERSION
WRITE
MODE
24h
REGISTER
COMM.
WRITE
48h
Figure 22. Continuous Conversion, CH0 and CH1, Continuous Read
Figure 21. Continuous Conversion, CH0 and CH1, No Data Read
Figure 20. Continuous Conversion, CH0 and CH1, RDYFN = 1
CONVERSION
COMPLETE
CH1 CONVERSION
CH1 CONVERSION
ON CH0
Rev. A | Page 25 of 32
STATUS
STATUS
READ
CH0
00h
CH0 CONVERSION
CH0 CONVERSION
READ
DATA
CH0
DATA
and reading the result should always start before the next
conversion is completed.
The AD7732 will stay in continuous read mode as long as the
DIN pin is low while the CS pin is low; therefore, write 0 to the
AD7732 while reading in continuous read mode. To exit
continuous read mode, take the DIN pin high for at least 100 ns
after a read is complete. (Write 80h to the AD7732 to exit
continuous reading.)
Taking the DIN pin high does not change the Cont RD bit in
the mode register. Therefore, the next write of 48h starts the
continuous read mode again. To completely stop the continuous
read mode, write to the mode register to clear the Cont RD bit.
00h
READ
DATA
READ
DATA
CH1
CH0
DATA
00h
CONVERSION
COMPLETE
ON CH1
CH1 CONVERSION
CH1 CONVERSION
STATUS
STATUS
00h
READ
CH1
READ
DATA
DATA
CH0 CONVERSION
CH0 CONVERSION
CH0
00h
READ
DATA
CH1
READ
DATA
CH1
DATA
00h
AD7732