AD7940 datasheet(13/24 Pages) AD

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Preliminary Technical Data

AD7693

Rev. PrB | Page 13 of 24

TYPICAL CONNECTION DIAGRAM

Transfer Functions

Figure 26 shows an example of the recommended connection

diagram for the AD7693 when multiple supplies are available.

The ideal transfer characteristic for the AD7693 is shown in

Figure 25 and Table 7.

100...000

100...001

100...010

011...101

011...110

011...111

ANALOG INPUT

+FSR – 1.5LSB

+FSR – 1LSB

–FSR + 1LSB

–FSR

–FSR + 0.5LSB

Figure 25. ADC Ideal Transfer Function

Table 7. Output Codes and Ideal Input Voltages

Analog Input

VREF = 5 V

Digital Output

Code (Hex)

Description

FSR − 1 LSB

+4.999847 V

0x7FFF1

Midscale + 1 LSB

+152.6 μV

0x0001

Midscale

0 V

0x0000

Midscale − 1 LSB

−152.6 μV

0xFFFF

−FSR + 1 LSB

−4.999847 V

0x8001

−FSR

−5 V

0x80002

1 This is also the code for an overranged analog input (VIN+ − VIN− above VREF − VGND).

2 This is also the code for an underranged analog input (VIN+ − VIN− below VGND).

AD7693

REF

GND

VDD

IN–

IN+

VIO

SDI

SCK

SDO

CNV

3- OR 4-WIRE INTERFACE5

100nF

10µF2

V+

V–

1.8V TO VDD

REF1

0 TO VREF

2.7nF

V+

V–

VREF TO 0

2.7nF

ADA4841-23

1 SEE REFERENCE SECTION FOR REFERENCE SELECTION.

2 CREF IS USUALLY A 10µF CERAMIC CAPACITOR (X5R).

3 SEE TABLE 8 FOR ADDITIONAL RECOMMENDED AMPLIFIERS.

4 OPTIONAL FILTER. SEE ANALOG INPUT SECTION.

5 SEE THE DIGITAL INTERFACE SECTION FOR MOST CONVENIENT INTERFACE MODE.

Figure 26. Typical Application Diagram with Multiple Supplies

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