OP400
Data Sheet
DIFFERENTIAL OUTPUT INSTRUMENTATION
AMPLIFIER
BIPOLAR CURRENT TRANSMITTER
In the circuit of Figure 32, which is an extension of the standard
three op amp instrumentation amplifier, the output current is
proportional to the differential input voltage. Maximum output
current is 5 mA, with voltage compliance equal to 10 V when
using 15 V supplies. Output impedance of the current
transmitter exceeds 3 MΩ, and linearity is better than 16 bits
with gain set for a full-scale input of 100 µV.
The output voltage swing of a single-ended instrumentation
amplifier is limited by the supplies, normally at 15 V, to
a maximum of 24 V p-p. The differential output instrumenta-
tion amplifier shown in Figure 33 can provide an output voltage
swing of 48 V p-p when operated with 15 V supplies. The
extended output swing is due to the opposite polarity of the
outputs. Both outputs swing 24 V p-p, but with opposite
polarity, for a total output voltage swing of 48 V p-p. The reference
input can be used to set a common-mode output voltage over the
range 10 V. The PSRR of the amplifier is less than 1 µV/V with
CMRR (G = 1000) better than 115 dB. Offset voltage drift is
typically 0.4 µV/°C over the military temperature range.
–
+
25kΩ
25kΩ
1/4
OP400E
–
V
–
OUT
1/4
200Ω
IOUT
5mA
OP400E
25kΩ
25kΩ
+
V
R
IN
G
–
+
1/4
1/4
25kΩ
25kΩ
OP400E
OP400E
–
+
+
V
IN
200Ω
50,000
–
R
G
–
1
IOUT
Figure 32. Bipolar Current Transmitter
22pF
–
+
1/4
25kΩ
25kΩ
OP400A
–
+
25kΩ
1/4
OP400A
V
R
G
IN
–
25kΩ
22pF
–
1/4
25kΩ
25kΩ
OP400A
22pF
+
+
25kΩ
22pF
V
50kΩ + R
IN
G
=
V
R
G
OUT
25kΩ
V
OUT
–
1/4
OP400A
REFERENCE
INPUT
+
Figure 33. Differential Output Instrumentation Amplifier
Rev. H | Page 12 of 16
ADI [ ADI ]
