AD7796 Analog Devices, AD7796 Datasheet - Page 23

• Manufacturer Part Number: AD7796
• Description: Low Power 16-Bit Sigma-Delta A/D Converter for Bridge Sensors
• Manufacturer: Analog Devices

Specifications of AD7796

• Resolution (bits): 16bit
• # Chan: 1
• Sample Rate: n/a
• Interface: Ser,SPI
• Analog Input Type: Diff-Bip,Diff-Uni
• Ain Range: ± (Vref/128)
• Adc Architecture: Sigma-Delta
• Pkg Type: SOP

APPLICATIONS
The AD7796/AD7797 offer a high resolution analog-to-digital
function. Because the analog-to-digital function is provided by
a Σ-Δ architecture, the parts are more immune to noisy
environments, making them ideal for use in sensor
measurement, and industrial and process-control applications.
WEIGH SCALES
Figure 17 shows the AD7796/AD7797 being used in a weigh
scale application. The load cell is arranged in a bridge network
and gives a differential output voltage between its OUT+ and
OUT– terminals. Assuming a 5 V excitation voltage, the full-
OUT–
IN+
IN–
V
DD
OUT+
Figure 17. Weigh Scales Using the AD7796/AD7797
AIN(+)
AIN(–)
REFIN(+)
REFIN(–)
SENSOR
TEMP
MUX
AV
GND
DD
Rev. A | Page 23 of 24
GND
V
DD
×128
scale output range from the transducer is 10 mV when the
sensitivity is 2 mV/V. The excitation voltage for the bridge can
be used to directly provide the reference for the ADC because
the reference input range includes the supply voltage. This
allows a ratiometric measurement. Therefore, variations of the
excitation voltage do not affect the measurement.
The on-chip temperature sensor can be used for temperature
compensation of the bridge so the variation of the sensor
resistance with temperature drift can be monitored and the
conversions from the bridge can be compensated.
ADC
AD7796/AD7797
Σ-Δ
INTERFACE
INTERNAL
CONTROL
CLOCK
SERIAL
LOGIC
AND
CLK
DOUT/RDY
DIN
SCLK
CS
DV
DD
AD7796/AD7797