AD7667AST datasheet(25/29 Pages) AD

25 / 29 page

AD7667

Rev. 0 | Page 24 of 28

SLAVE SERIAL INTERFACE

External Clock

The AD7667 is configured to accept an externally supplied

serial data clock on the SCLK pin when the EXT/INT pin is

held HIGH. In this mode, several methods can be used to read

the data. The external serial clock is gated by CS. When CS and

RD are both LOW, the data can be read after each conversion or

during the following conversion. The external clock can be

either a continuous or a discontinuous clock. A discontinuous

clock can be either normally HIGH or normally LOW when

inactive. Figure 41 and Figure 42 show the detailed timing

diagrams of these methods. Usually, because the AD7667 has a

longer acquisition phase than conversion phase, the data are

read immediately after conversion.

While the AD7667 is performing a bit decision, it is important

that voltage transients be avoided on digital input/output pins

or degradation of the conversion result could occur. This is

particularly important during the second half of the conversion

phase because the AD7667 provides error correction circuitry

that can correct for an improper bit decision made during the

first half of the conversion phase. For this reason, it is

recommended that when an external clock is being provided, it

is a discontinuous clock that is toggling only when BUSY is

LOW, or, more importantly, that it does not transition during

the latter half of BUSY HIGH.

SCLK

SDOUT

D15

D14

D13

X15

X14

X13

Y15

Y14

BUSY

SDIN

INVSCLK = 0

t35

t36 t37

t31

t32

t16

t33

X15

X14

151617

t34

EXT/INT = 1

RD = 0

Figure 41. Slave Serial Data Timing for Reading (Read after Convert)

SDOUT

SCLK

D15

D14

D13

t35

t36 t37

t31

t32

t16

BUSY

EXT/INT = 1

INVSCLK = 0

CNVST

RD = 0

Figure 42. Slave Serial Data Timing for Reading (Read Previous Conversion during Convert)

AD7667AST Datenblatt(PDF) 25 Page - Analog Devices

AD7667AST Datenblatt(HTML) 25 Page - Analog Devices

Html Pages

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29

Datenblatt Download

Link URL