
AD524
Rev. F | Page 19 of 28
AD524
REF
SENSE
LOAD
AD711
+INPUT
–INPUT
R1
=
(1 +
R1
)
40,000
A2
+
–
VX
IL
RG
IL
VX
VIN
2
3
13
1
10
9
6
0
0500-
046
AD524
REF
SENSE
LOAD
AD711
VOFFSET
–VS
+VS
VIN+
VIN–
2
8
10
9
6
7
3
12
1
0
500
-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
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, IL, 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
K3
D1
D2
D3
NC
GAIN TABLE
AB GAIN
0
1
0
1
0
1
10
1000
100
1
NC = NO CONNECT
1
2
3
4
5
6
7
8
20k
404
4.44k
20k
40
PROTECTION
16
15
14
13
12
11
10
9
INPUT
OFFSET
TRIM
ANALOG
COMMON
–VS
+VS
K1 – K3 =
THERMOSEN DM2C
4.5V COIL
D1 – D3 = IN4148
INPUTS
GAIN
RANGE
A1
AD524
LOGIC
COMMON
10F
7407N
BUFFER
DRIVER
74LS138
DECODER
G = 1000
K3
G = 100
K2
G = 10
K1
OUTPUT
OFFSET
TRIM
RELAY
SHIELDS
R1
10k
+VS
R2
10k
1F
35V
1
16
15
14
13
2
3
4
5
6
7
1
16
2
3
4
5
6
7
00
50
0-
0
47
Figure 47. Three-Decade Gain Programmable Amplifier