AD4011 datasheet(30/38 Pages) AD

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AD4003/AD4007/AD4011

Data Sheet

Rev. B | Page 30 of 38

CS MODE, 3-WIRE WITHOUT BUSY INDICATOR

This mode is typically used when a single AD4003/AD4007/

AD4011 device is connected to an SPI-compatible digital host.

The connection diagram is shown in Figure 55, and the

corresponding timing diagram is shown in Figure 56.

With SDI tied to VIO, a rising edge on CNV initiates a conversion,

selects the CS mode, and forces SDO to high impedance. After a

conversion is initiated, it continues until completion irrespective of

the state of CNV. This feature can be useful, for instance, to bring

CNV low to select other SPI devices, such as analog multiplexers;

however, CNV must be returned high before the minimum

conversion time elapses and then held high for the maximum

possible conversion time to avoid the generation of the busy

signal indicator.

When the conversion is complete, the AD4003/AD4007/

AD4011 enter the acquisition phase and power down. When

CNV goes low, the MSB is output onto SDO. The remaining data

bits are clocked by subsequent SCK falling edges. The data is valid

on both SCK edges. Although the rising edge can capture the data,

a digital host using the SCK falling edge allows a faster reading

rate, provided it has an acceptable hold time. After the 18th SCK

falling edge or when CNV goes high (whichever occurs first),

SDO returns to high impedance.

There must not be any digital activity on SCK during the

conversion.

AD4003/AD4007/

AD4011

SDI

SDO

CNV

SCK

CONVERT

DATA IN

CLK

DIGITAL HOST

VIO

Figure 55. CS Mode, 3-Wire Without Busy Indicator Connection Diagram (SDI High)

SDO

D17

D16

D15

tDIS

SCK

tSCK

tSCKL

tSCKH

tHSDO

tDSDO

CNV

CONVERSION

ACQUISITION

tCYC

ACQUISITION

SDI = 1

tCNVH

tACQ

tEN

tQUIET2

tCONV

Figure 56. CS Mode, 3-Wire Without Busy Indicator Serial Interface Timing Diagram (SDI High)

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