AD7660(2016) View Datasheet(PDF) - Analog Devices

Part Name

Description

Manufacturer

AD7660
(Rev.:2016)

16-Bit, 100 kSPS PulSAR® Unipolar CMOS ADC

Analog Devices 

AD7660

Transfer Functions

Using the OB/2C digital input, the AD7660 offers two output

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

VREF/65536, which is about 38.15 mV. The ideal transfer charac-

teristic for the AD7660 is shown in Figure 4 and Table II.

111...111

111...110

111...101

1 LSB = VREF/65536

000...010

000...001

000...000

0V

1 LSB

0.5 LSB

VREF –1 LSB

VREF –1.5 LSB

ANALOG INPUT

Figure 4. ADC Ideal Transfer Function

Table II. Output Codes and Ideal Input Voltages

Description

Analog

Input

Digital Output Code (Hex)

Straight

Binary

Twos

Complement

FSR – 1 LSB

2.499962 V FFFF1

FSR – 2 LSB

2.499923 V FFFE

Midscale + 1 LSB 1.250038 V 8001

Midscale

1.25 V

8000

Midscale – 1 LSB 1.249962 V 7FFF

–FSR + 1 LSB

–FSR

38 mV

0V

0001

00002

7FFF1

7FFE

0001

0000

FFFF

8001

80002

NOTES

1This is also the code for overrange analog input (VIN – VINGND above

VREF – VREFGND).

2This is also the code for underrange analog input (VIN below VINGND).

TYPICAL CONNECTION DIAGRAM

Figure 5 shows a typical connection diagram for the AD7660.

ANALOG

SUPPLY

(5V)

10␮F 100nF

100⍀

10␮F 100nF

100nF

10␮F

DIGITAL SUPPLY

(3.3V OR 5V)

2.5V REF

NOTE 1

CREF

NOTE 1

ANALOG INPUT

(0V TO 2.5V)

NOTE 2 U1

AVDD AGND

REF

REFGND

IN

DGND DVDD OVDD OGND

SCLK

SDOUT

AD7660

BUSY

CNVST

INGND

PD

RESET

OB/ 2C

SER/ PAR

CS

RD

SERIAL

PORT

D

NOTE 3

DVDD

␮C/ ␮P/DSP

CLOCK

NOTES

1. WITH THE AD780 OR THE ADR291 VOLTAGE REFERENCE, CREF IS 47␮F,

SEE VOLTAGE REFERENCE INPUT SECTION.

2. THE OP184 IS RECOMMENDED.

3. OPTIONAL LOW JITTER CNVST.

Figure 5. Typical Connection Diagram

REV. E

–11–

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