EVAL-AD7687SDZ(RevC) Ver la hoja de datos (PDF) - Analog Devices

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EVAL-AD7687SDZ
(Rev.:RevC)

16-Bit, 1.5 LSB INL, 250 kSPS PulSAR Differential ADC in MSOP

Analog Devices 

AD7687

Transfer Functions

The ideal transfer characteristic for the AD7687 is shown in

Figure 26 and Table 9.

011...111

011...110

011...101

Data Sheet

TYPICAL CONNECTION DIAGRAM

Figure 27 shows an example of the recommended connection

diagram for the AD7687 when multiple supplies are available.

100...010

100...001

100...000

–FSR

–FSR + 1 LSB

–FSR + 0.5 LSB

+FSR – 1 LSB

+FSR – 1.5 LSB

ANALOG INPUT

Figure 26. ADC Ideal Transfer Function

Table 9. Output Codes and Ideal Input Voltages

Description

FSR – 1 LSB

Analog Input

VREF = 5 V

+4.999847 V

Digital Output Code Hexa

7FFF1

Midscale + 1 LSB +152.6 µV

0001

Midscale

0V

0000

Midscale – 1 LSB −152.6 µV

FFFF

–FSR + 1 LSB

−4.999847 V 8001

–FSR

−5 V

80002

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

−VREF + VGND).

≥7V

REF1

10µF2

≥7V

0 TO VREF

3

≤ –2V

≥7V

VREF TO 0

3

≤ –2V

33Ω

2.7nF

4

33Ω

2.7nF

4

REF

IN+

VDD

VIO

SDI

SCK

AD7687

SDO

IN–

GND

CNV

100nF

100nF

5V

1.8V TO VDD

3- OR 4-WIRE INTERFACE5

1SEE VOLTAGE INPUT REFERENCE SECTION FOR REFERENCE SELECTION.

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

3SEE DRIVER AMPLIFIER CHOICE SECTION.

4OPTIONAL FILTER. SEE ANALOG INPUT SECTION.

5SEE DIGITAL INTERFACE FOR MOST CONVENIENT INTERFACE MODE.

Figure 27. Typical Application Diagram with Multiple Supplies

Rev. C | Page 14 of 28

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