AD7715ANZ-3 Analog Devices Inc, AD7715ANZ-3 Datasheet - Page 27

• Manufacturer Part Number: AD7715ANZ-3
• Description: IC ADC 16BIT SIGMA-DELTA 16DIP
• Manufacturer: Analog Devices Inc

Specifications of AD7715ANZ-3

• Data Interface: DSP, MICROWIRE™, QSPI™, Serial, SPI™
• Number Of Bits: 16
• Sampling Rate (per Second): 500
• Number Of Converters: 1
• Power Dissipation (max): 9.5mW
• Voltage Supply Source: Analog and Digital
• Operating Temperature: -40°C ~ 85°C
• Mounting Type: Through Hole
• Package / Case: 16-DIP (0.300", 7.62mm)
• Resolution (bits): 16bit
• Input Channel Type: Differential
• Supply Voltage Range - Analogue: 3V To 3.6V
• Supply Voltage Range - Digital: 3V To 5.25V
• Supply Current: 600µA
• No. Of: RoHS Compliant
• Sampling Rate: 19.2kSPS
• Rohs Compliant: Yes
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• For Use With: EVAL-AD7715-3EBZ - BOARD EVALUATION FOR AD7715
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

REV. C
APPLICATIONS
The AD7715 provides a low cost, high resolution analog-to-
digital function. Because the analog-to-digital function is pro-
vided by a sigma-delta architecture, it makes the part more
immune to noisy environments thus making the part ideal for
use in industrial and process control applications. It also
provides a programmable gain amplifier, a digital filter and
calibration options. Thus, it provides far more system level
functionality than off-the-shelf integrating ADCs without the
disadvantage of having to supply a high quality integrating ca-
pacitor. In addition, using the AD7715 in a system allows the
system designer to achieve a much higher level of resolution
because noise performance of the AD7715 is significantly better
than that of the integrating ADCs.
The on-chip PGA allows the AD7715 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 AD7715.
The programmable gain front end on the AD7715 allows the
part to handle unipolar analog input ranges from 0 mV to
OUT–
EXCITATION VOLTAGE = +5V
IN–
IN+
OUT+
24k
15k
Figure 12. Pressure Measurement Using the AD7715
REF IN (+)
REF IN (–)
AGND
AIN(–)
AIN(+)
REF
= +1.25 V.
+5V
BUFFER
AV
DGND
DD
DD
A = 1–128
PGA
DV
–27–
SERIAL INTERFACE
DD
DOUT
+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 AD7715 is pressure measurement.
Figure 12 shows the AD7715 used with a pressure transducer,
the BP01 from Sensym. The pressure transducer is arranged in a
bridge network and gives a differential output voltage between
its OUT(+) and OUT(–) terminals. With rated full-scale pres-
sure (in this case 300 mmHg) on the transducer, the differential
output voltage is 3 mV/V 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
AD7715. 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 AD7715 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 AD7715 being 15 mV which corresponds
with the output span from the transducer.
2.5 V. Because the part operates from a single supply, these
AUTO-ZEROED
CHARGE BALANCING A/D
MODULATOR
REGISTER BANK
DIN
CONVERTER
AD7715
CS
GENERATION
DIGITAL
FILTER
CLOCK
SCLK
MCLK IN
MCLK OUT
RESET
DRDY
AD7715