Datasheet

AD7787 Data Sheet
Rev. A | Page 16 of 20
Single Conversion Mode
In single conversion mode, the AD7787 is placed in shutdown
mode between conversions. When a single conversion is
initiated by setting MD1 to 1 and MD0 to 0 in the mode
register, the AD7787 powers up, performs a single conversion,
and then returns to shutdown mode. When a single conversion
is initiated, the AD7787’s oscillator requires 1 ms to power up
and settle. The AD7787 then performs a conversion which
requires 2 × t
ADC
. DOUT/
RDY
is high while the conversion is
being performed and goes low to indicate the completion of the
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 AD7787 will
continuously converts with the
RDY
pin in the status register
going 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 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 or the new
conversion word is lost.
04477-0-009
DIN
SCLK
DOUT/RDY
CS
0x38
0x38
DATA DATA
Figure 14. Continuous Conversion