Datasheet

AD7792/AD7793
Rev. B | Page 22 of 32
Single Conversion Mode
In single conversion mode, the AD7792/AD7793 are placed in
shutdown mode between conversions. When a single conver-
sion is initiated by setting MD2, MD1, MD0 to 0, 0, 1 in the
mode register, the AD7792/AD7793 power up, perform a single
conversion, and then return 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 AD7792/AD7793
continuously converts, the
RDY
pin in the status register going
low each time a conversion is completed. If
CS
is low, the
DOUT/
RDY
line also goes low when a conversion is complete.
To read a conversion, the user writes to the communications
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, otherwise the
new conversion word is lost.
0x58
04855-015
DIN
0x08 0x200A
DATA
SCLK
DOUT/RDY
CS
Figure 17. Single Conversion
0
4855-016
DIN
SCLK
DOUT/RDY
CS
0x58 0x58
DATA DATA
Figure 18. Continuous Conversion