EVAL-AD7714-3EBZ Analog Devices Inc, EVAL-AD7714-3EBZ Datasheet - Page 34

• Manufacturer Part Number: EVAL-AD7714-3EBZ
• Description: BOARD EVALUATION FOR AD7714
• Manufacturer: Analog Devices Inc

Specifications of EVAL-AD7714-3EBZ

• Number Of Adc's: 1
• Number Of Bits: 24
• Sampling Rate (per Second): 1k
• Data Interface: Serial
• Inputs Per Adc: 3 Differential
• Input Range: 0 ~ 3.3 V
• Power (typ) @ Conditions: 3.65mW @ 3.3 V
• Voltage Supply Source: Analog and Digital
• Operating Temperature: -40°C ~ 85°C
• Utilized Ic / Part: AD7714-3
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

AD7714
APPLICATIONS
The on-chip PGA allows the AD7714 to handle an analog input
voltage range as low as 10 mV full-scale with V
The differential inputs of the part allow this analog input range
to have an absolute value anywhere between AGND and AV
when the part is operated in unbuffered mode. It allows the user
to connect the transducer directly to the input of the AD7714.
The programmable gain front end on the AD7714 allows the
part to handle unipolar analog input ranges from 0 mV to
+20 mV to 0 V to +2.5 V and bipolar inputs of 20 mV to
bipolar ranges are with respect to a biased-up differential input.
Pressure Measurement
One typical application of the AD7714 is pressure measure-
ment. Figure 12 shows the AD7714 used with a pressure trans-
ducer, the BP01 from Sensym. The pressure transducer is
2.5 V. Because the part operates from a single supply these
OUT–
EXCITATION VOLTAGE = +5V
IN–
IN+
OUT+
24k
15k
Figure 12. Pressure Measurement Using the AD7714
REF IN (+)
REF IN (–)
AGND
AIN1
AIN2
AIN3
AIN4
AIN5
AIN6
REF
= +1.25 V.
AGND
AV
+5V
AV
DD
DGND
DD
1 A
1 A
BUFFER
DD
BUFFER DOUT
–34–
DV
SERIAL INTERFACE
DD
A = 1–128
arranged in a bridge network and gives a differential output
voltage between its OUT(+) and OUT(–) terminals. With rated
full-scale pressure (in this case 300 mmHg) on the transducer,
the differential output voltage is 3 mV/Volt of the input voltage
(i.e., the voltage between its IN(+) and IN(–) terminals).
Assuming a 5 V excitation voltage, the full-scale output range
from the transducer is 15 mV. The excitation voltage for the
bridge is also used to generate the reference voltage for the
AD7714. Therefore, variations in the excitation voltage do not
introduce errors in the system. Choosing resistor values of
24 k and 15 k as per the diagram give a 1.92 V reference
voltage for the AD7714 when the excitation voltage is 5 V.
Using the part with a programmed gain of 128 results in the full
scale input span of the AD7714 being 15 mV which corresponds
with the output span from the transducer.
PGA
REGISTER BANK
AUTO-ZEROED
CHARGE BALANCING A/D
MODULATOR
DIN
CONVERTER
CS
GENERATION
AD7714
CLOCK
SCLK
DIGITAL
FILTER
MCLK OUT
STANDBY
SYNC
MCLK IN
RESET
DRDY
POL
REV. C