Datasheet

AD7796/AD7797
Rev. A | Page 18 of 24
Single Conversion Mode
In single conversion mode, the AD7796/AD7797 are placed in
shutdown mode between conversions. When a single conver-
sion is initiated by setting MD2, MD1, and MD0 in the mode
register to 0, 0, and 1, respectively, the part powers up, performs
a single conversion, and then returns to shutdown mode. The
on-chip oscillator requires 1 ms to power-up. A conversion
requires a time period of 2 × t
ADC
. DOUT/
RDY
goes low to
indicate the completion of a conversion. When the data-word
has been read from the data register, DOUT/
RDY
goes high. If
CS
is low, DOUT/
RDY
remains high until another conversion is
initiated and completed. The data register can be read several
times, if required, even when DOUT/
RDY
has gone high.
Continuous Conversion Mode
This is the default power-up mode. The AD7796/AD7797
continuously convert, and the
RDY
pin in the status register
goes low each time a conversion is complete. If
CS
is low, the
DOUT/
RDY
line also goes low when a conversion is complete.
To read a conversion, the user can write to the communication
register, indicating that the next operation is a read of the data
register. The digital conversion is placed on the DOUT/
RDY
pin as soon as SCLK pulses are applied to the ADC. DOUT/
RDY
returns high when the conversion is read. The user can read this
register additional times, if required. However, the user must
ensure that the data register is not being accessed at the completion
of the next conversion, or the new conversion word is lost.
0x58
DIN
0x08 0x200A
DATA
SCLK
DOUT/RDY
CS
06083-014
Figure 14. Single Conversion
DIN
SCLK
DOUT/RDY
CS
0x58 0x58
DATA DATA
06083-015
Figure 15. Continuous Conversion