Datasheet

REV. F
AD7712
–27–
CLOCK
GENERATION
SERIAL INTERFACE
OUTPUT
REGISTER
CHARGE-BALANCING A/D
CONVERTER
AUTO-ZEROED
⌺–⌬
MODULATOR
DIGITAL
FILTER
AD7712
AGND
DGND
MODE SDATA SCLK A0
MCLK OUT
MCLK IN
AIN1(+)
AIN1(–)
REF
IN (–)
REF
IN (+)
SYNC
4.5␮A
A = 1 – 128
DRDY
TFSRFS
REF OUT
2.5V REFERENCE
VOLTAGE
ATTENUATION
AIN2
STANDBY
CONTROL
REGISTER
V
SS
500⍀
PGA
M
U
X
AV
DD
AV
DD
DV
DD
ANALOG +5V SUPPLY
V
BIAS
4–20mA
LOOP
Figure 20. 4–20 mA Loop Measurement Using the AD7712
APPLICATIONS
4–20 mA LOOP
The AD7712’s high level input can be used to measure the
current in 4–20 mA loop applications as shown in Figure 20. In
this case, the system calibration capabilities of the AD7712 can
be used to remove the offset caused by the 4 mA flowing
through the 500 Ω resistor. The AD7712 can handle an input
span as low as 3.2 ⫻ V
REF
(= 8 V with a V
REF
of 2.5 V) even
though the nominal input voltage range for the input is 10 V.
Therefore, the full span of the A/D converter can be used for
measuring the current between 4 mA and 20 mA.
24-Lead Standard Small Outline Package [SOIC]
Wide Body
(RW-24)
Dimensions shown in millimeters and (inches)
CONTROLLING DIMENSIONS ARE IN MILLIMETERS; INCH DIMENSIONS
(IN PARENTHESES) ARE ROUNDED-OFF MILLIMETER EQUIVALENTS FOR
REFERENCE ONLY AND ARE NOT APPROPRIATE FOR USE IN DESIGN
COMPLIANT TO JEDEC STANDARDS MS-013AD
8ⴗ
0ⴗ
0.75 (0.0295)
0.25 (0.0098)
ⴛ 45ⴗ
1.27 (0.0500)
0.40 (0.0157)
SEATING
PLANE
0.30 (0.0118)
0.10 (0.0039)
2.65 (0.1043)
2.35 (0.0925)
1.27 (0.0500)
BSC
24 13
12
1
10.65 (0.4193)
10.00 (0.3937)
7.60 (0.2992)
7.40 (0.2913)
15.60 (0.6142)
15.20 (0.5984)
COPLANARITY
0.10
0.33 (0.0130)
0.20 (0.0079)
0.51 (0.0201)
0.31 (0.0122)
OUTLINE DIMENSIONS