AD7664 View Datasheet(PDF) - Analog Devices

Part Name

Description

Manufacturer

AD7664

16-Bit, 570 kSPS PulSAR® Unipolar CMOS ADC

Analog Devices 

AD7664

The Normal Mode is the fastest mode (500 kSPS) without any

limitation on the time between conversions. This mode makes the

AD7664 ideal for asynchronous applications such as data

acquisition systems, where both high accuracy and fast sample

rate are required.

The Impulse Mode, the lowest power dissipation mode, allows

power saving between conversions. When operating at 100 SPS,

for example, it typically consumes only 21 µW. This feature

makes the AD7664 ideal for battery-powered applications.

Transfer Functions

Using the OB/2C digital input, the AD7664 offers two output

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

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

teristics for the AD7664 are shown in Figure 4 and Table II.

111...111

111...110

111...101

1 LSB = VREF/65536

Table II. Output Codes and Ideal Input Voltages

Description

Analog

Input

Digital Output Code

Hexa

Straight Twos

Binary Complement

FSR – 1 LSB

FSR – 2 LSB

Midscale + 1 LSB

Midscale

Midscale – 1 LSB

–FSR + 1 LSB

–FSR

2.499962 V

2.499923 V

1.250038 V

1.25 V

1.249962 V

38 µV

0V

FFFF1

FFFE

8001

8000

7FFF

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 AD7664.

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

ANALOG

SUPPLY

(5V)

10␮F 100nF

100⍀

10␮F 100nF

100nF

10␮F

DIGITAL SUPPLY

(3.3V OR 5V)

AVDD AGND

DGND DVDD OVDD OGND

2.5V REF1

CREF1

REF

1␮F

REFGND

ANALOG INPUT

(0V TO 2.5V)

15⍀

U12

IN

CC

4.7nF

INGND

PD

AD7664

RESET

CS

SCLK

SDOUT

BUSY

CNVST

OB/ 2C

SER/ PAR

WARP

IMPULSE

RD

SERIAL

PORT

D3

DVDD

␮C/␮P/DSP

CLOCK

NOTES

1THE ADR421 IS RECOMMENDED WITH CREF = 47␮F.

2THE AD8021 IS RECOMMENDED WITH A COMPENSATION CAPACITOR CC = 10 pF, TYPE CERAMIC NPO.

3OPTIONAL LOW JITTER CNVST.

Figure 5. Typical Connection Diagram

–12–

REV. E

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