EVAL-AD7791EBZ datasheet(17/21 Pages) AD

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AD7791

Data Sheet

Rev. A | Page 16 of 20

Single Conversion Mode

In single conversion mode, the AD7791 is placed in shutdown

mode between conversions. When a single conversion is initiat-

ed by setting MD1 to 1 and MD0 to 0 in the mode register, the

AD7791 powers up, performs a single conversion, and then

returns to shutdown mode. A conversion will require a time

period of 2 × tADC. DOUT/RDY goes low to indicate the com-

pletion of a conversion. When the data-word has been read

from the data register, DOUT/RDY will go high. If CS is low,

DOUT/RDY will remain high until another conversion is initi-

ated 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 AD7791 will continu-

ously convert, the RDY pin in the status register going low each

time a conversion is complete. If CS is low, the DOUT/RDY line

will also go low when a conversion is complete. To read a con-

version, the user can write to the communications register,

indicating that the next operation is a read of the data register.

The digital conversion will be placed on the DOUT/RDY pin as

soon as SCLK pulses are applied to the ADC. DOUT/RDY will

return high when the conversion is read. The user can read this

ensure that the data register is not being accessed at the comple-

tion of the next conversion or else the new conversion word will

be lost.

04227-0-009

DIN

SCLK

DOUT/RDY

0x38

DATA

Figure 14. Continuous Conversion

EVAL-AD7791EBZ Datasheet(PDF) 17 Page - Analog Devices