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EVAL-CEDZ

1 MSPS, 14-Bit, Simultaneous Sampling SAR ADC with PGA and Four Comparators

Analog Devices 

RS

SENSOR

RS

RF

Cx–

Cx+

COUTx

Figure 28. Recommended Comparator Connection Diagram

APPLICATION DETAILS

The AD7264 has been specifically designed to meet the require-

ments of any motor control shaft position feedback loop. The

device can interface directly to multiple sensor types, including

optical encoders, magnetoresistive sensors, and Hall effect sensors.

Its flexible analog inputs, which incorporate programmable

gain, ensure that identical board design can be utilized for a

AD7264

variety of sensors, which results in reduced design cycles and

costs.

The two simultaneous sampling ADCs are used to sample the

sine and cosine outputs from the sensor. No external buffering

is required between the sensor/transducer and the analog inputs

of the AD7264. The on-chip comparators can be used to

monitor the pole sensors, which can be Hall effect sensors or

the inner tracks from an optical encoder.

Figure 29 shows how the AD7264 can be used in a typical

application. An optical encoder is shown in Figure 29, but other

sensor types could as easily be used. Figure 29 indicates a

typical application configuration only; there are several other

configurations that render equally effective results.

COMP

COMP

AVCC

VREFA

A

B

H.E.

Z

U

V

W

REF

BUF

AD7264

VA+

VA–

PGA

T/H

14-BIT

SUCCESSIVE

APPROXIMATION

OUTPUT

DRIVERS

ADC

CONTROL

LOGIC

VB+

VB–

VREFB

CA_CBVCC

CA+

CA–

CB+

CB–

CA_CB_GND

CC_CDVCC

CC+

CC–

CD+

CD–

CC_CD_GND

PGA

14-BIT

T/H

SUCCESSIVE

OUTPUT

APPROXIMATION DRIVERS

ADC

BUF

COMP

OUTPUT

DRIVERS

COMP

OUTPUT

DRIVERS

COMP

OUTPUT

DRIVERS

COMP

OUTPUT

DRIVERS

DOUTA

SCLK

CAL

CS

REFSEL

G0

G1

G2

G3

VDRIVE

DOUTB

PD0/DIN

PD1

PD2

COUTA

COUTB

COUTC

COUTD

AGND

DGND

Figure 29. Typical System Connection Diagram with Optical Encoder

Rev. A | Page 19 of 32

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