Datasheet
AD524
Rev. F | Page 19 of 28
AD524
REF
SENSE
LOAD
AD711
+INPUT
–INPUT
R1
R1
===
(
1 +
R1
)
40,000
A2
+
–
V
X
I
L
R
G
I
L
V
X
V
IN
2
3
13
1
10
9
6
00500-046
AD524
REF
SENSE
LOAD
AD711
V
OFFSET
–V
S
+V
S
V
IN
+
V
IN
–
2
8
10
9
6
7
3
12
1
0
0500-045
Figure 45. Use of Reference Terminal to Provide Output Offset
Figure 46. Voltage-to-Current Converter
An instrumentation amplifier can be turned into a voltage-
to-current converter by taking advantage of the sense and
reference terminals, as shown in Figure 46.
By establishing a reference at the low side of a current setting
resistor, an output current may be defined as a function of input
voltage, gain, and the value of that resistor. Because only a small
current is demanded at the input of the buffer amplifier (A2)
the forced current, I
L
, largely flows through the load. Offset and
drift specifications of A2 must be added to the output offset and
drift specifications of the AD524.
Y0
Y2
Y1
+5V
C1
C2
A
B
+5V
–IN
+IN
OUT
K1 K2 K3D1 D2 D3
NC
GAIN TABLE
ABGAIN
0
0
1
1
0
1
0
1
10
1000
100
1
NC = NO CONNECT
1
2
3
4
5
6
7
8
20kΩ
20kΩ
20kΩ
404Ω
4.44kΩ
20kΩ
20kΩ
20kΩ
40Ω
PROTECTION
PROTECTION
16
15
14
13
12
11
10
9
INPUT
OFFSET
TRIM
ANALOG
COMMON
–V
S
+V
S
K1 – K3 =
THERMOSEN DM2C
4.5V COIL
D1 – D3 = IN4148
INPUTS
GAIN
RANGE
A1
AD524
LOGIC
COMMON
10µF
7407N
BUFFER
DRIVER
74LS138
DECODER
G = 1000
K3
G = 100
K2
G = 10
K1
OUTPUT
OFFSET
TRIM
RELAY
SHIELDS
R1
10kΩ
+V
S
R2
10kΩ
1µF
35V
1
16
15
14
13
2
3
4
5
6
7
1
16
2
3
4
5
6
7
00500-047
Figure 47. Three-Decade Gain Programmable Amplifier