Datasheet

Data Sheet AD7264
Rev. B | Page 19 of 28
06732-028
R
S
R
F
C
x–
C
x+
R
S
SENSOR
C
OUT
x
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 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.
V
A
+
V
A
–
V
B
+
V
B
–
V
REF
B
Z
B
A
U
V
W
COMP
COMP
H.E.
C
B
+
C
B
–
C
A
+
C
A
–
C
D
+
C
D
–
C
C
+
C
C
–
C
A
_C
B
V
CC
C
A
_C
B
_GND
C
C
_C
D
V
CC
C
C
_C
D
_GND
06732-029
AGND DGND
D
OUT
B
PD1
PD0/D
IN
PD2
V
REF
A
AV
CC
COMP
COMP
COMP
COMP
C
OUT
C
C
OUT
B
C
OUT
A
C
OUT
D
D
OUT
A
PGA T/H
BUF
T/H
BUF
PGA
14-BIT
SUCCESSIVE
APPROXIMATION
ADC
REF
14-BIT
SUCCESSIVE
APPROXIMATION
ADC
CONTROL
LOGIC
OUTPUT
DRIVERS
OUTPUT
DRIVERS
OUTPUT
DRIVERS
OUTPUT
DRIVERS
V
DRIVE
G3
G2
G1
G0
CAL
CS
SCLK
REFSEL
AD7264
OUTPUT
DRIVERS
OUTPUT
DRIVERS
Figure 29. Typical System Connection Diagram with Optical Encoder