EVAL-AD7797EB datasheet(18/24 Pages) AD

18 / 24 page

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

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 × tADC. 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

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

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

Figure 14. Single Conversion

DIN

SCLK

DOUT/RDY

0x58

DATA

Figure 15. Continuous Conversion

EVAL-AD7797EB Datasheet(PDF) 18 Page - Analog Devices