AD7652

Transfer Functions

Using the OB/2C digital input, the AD7652 offers two output

codings: straight binary and twos complement. The LSB size is

transfer characteristic is shown in

and

.

Figure 21

Figure 21. ADC Ideal Transfer Function

Table 7

Table 7. Output Codes and Ideal Input Voltages

000...000

000...001

000...010

111...101

111...110

111...111

ANALOG INPUT

1LSB

0V

0.5 LSB

02964-0-003

Digital Output Code (Hex)

Description

Analog

Input

Straight

Binary

Twos

Complement

FSR –1 LSB

2.499962 V

FFFF1

7FFF1

FSR – 2 LSB

2.499923 V

FFFE

7FFE

Midscale + 1 LSB

1.250038 V

8001

0001

Midscale

1.25 V

8000

0000

Midscale – 1 LSB

1.249962 V

7FFF

FFFF

–FSR + 1 LSB

38 µV

0001

8001

–FSR

0 V

00002

80002

NOTES

µF CERAMIC CAPACITOR (X5R, 1206 SIZE) IS RECOMMENDED (e.g., PANASONIC ECJ3YB0J106M).

SEE VOLTAGE REFERENCE INPUT SECTION.

AD7652

CLOCK

µC/µP/DSP

SERIAL

PORT

DIGITAL SUPPLY

(3.3V OR 5V)

DVDD

100nF

+

10

100nF

+

10

20

Ω

100nF

+

10

ANALOG

SUPPLY

(5V)

2.7nF

15

Ω

ANALOG INPUT

(0V TO 2.5V)

PD

RESET

SER/PAR

OB/2C

BUSY

SDOUT

SCLK

INGND

IN

REFGND

REF

GND

AVDD

DGND

DVDD

OVDD

OGND

02965-0-004

PDREF

PDBUF

RD

CS

BYTESWAP

CNVST

100nF

Figure 22. Typical Connection Diagram

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