AD7709 Analog Devices, AD7709 Datasheet - Page 28

• Manufacturer Part Number: AD7709
• Description: 16-Bit Sigma Delta ADC with Current Sources, Switchable Reference Inputs and I/O Port
• Manufacturer: Analog Devices

Specifications of AD7709

• Resolution (bits): 16bit
• # Chan: 4
• Sample Rate: n/a
• Interface: Ser,SPI
• Analog Input Type: Diff-Uni,SE-Uni
• Ain Range: (2Vref/PGA Gain) p-p
• Adc Architecture: Sigma-Delta
• Pkg Type: SOP

AD7709
Smart Transmitters
Smart transmitters are another key design-in area for the AD7709.
The - converter, single-supply operation, 3-wire interface
capabilities, and small package size are all of benefit in smart
transmitters. Here, the entire smart transmitter must operate
from the 4–20 mA loop. Tolerances in the loop mean that the
VARIABLES
10 F
AIN1
AIN2
AIN3
AIN4
0.1 F
GND
AD7709
REFIN(+)
REFIN(–)
V
DD
DOUT
SCLK
Figure 23. Smart Transmitter Employing the AD7709
DIN
CS
0.1 F
MICROCONTROLLER
GND
V
CC
–28–
amount of current available to power the transmitter is as low as
3.5 mA. Figure 23 shows a block diagram of a smart transmitter
that includes the AD7709.
Not shown in Figure 23 is the isolated power source required to
power the front end.
4.7 F
1.25V
3.3V
REF OUT2
REF IN
CLOCK
LATCH
DATA
COM
REF OUT1
10 F
C1
AD421
BOOST V
DN25D
C2
CC
0.01 F
C3
DRIVE
COMP
LOOP
LV
RTN
1000pF
0.01 F
1k
POWER
LOOP
REV. A