Datasheet

2
AD7714
REV. C
–37–
Data Acquisition
The AD7714 with its three differential channels (or five pseudo-
differential channels) is suited to low bandwidth, high resolution
data acquisition systems. In addition, the three-wire digital
interface allows this data acquisition front end to be isolated
with just three optoisolators. The entire system can be operated
from a single +3␣ V or +5 V supply provided that the input sig-
nals to the AD7714’s analog inputs are all of positive polarity.
The low power operation of the AD7714 ensures that very little
power has to be brought across the isolation barrier. Figure 15
shows the AD7714 in an isolated data acquisition system.
CLOCK
GENERATION
CHARGE BALANCING A/D
CONVERTER
DIGITAL
FILTER
AV
DD
1mA
BUFFER
AV
DD
SERIAL INTERFACE
REGISTER BANK
STANDBY
SYNC
MCLK IN
MCLK OUT
1mA
REF IN (+)
REF IN (–)
AGND
DGND
BUFFER
DOUT
DIN
CS
SCLK
POL
DRDY
RESET
DV
DD
AD7714
DV
DD
GND
+5V
AIN1
AIN2
AIN3
AIN4
AIN5
AIN6
V
OUT
AD780
+5V
+V
IN
A = 1–128
AGND
IN1+
IN1–
IN2+
IN2–
IN3+
IN3–
MICROCONTROLLER
OPTO-ISOLATORS
SWITCHING
MATRIX
PGA
AUTO-ZEROED
SD
MODULATOR
Figure 15. Data Acquisition System Using the AD7714