OP77 Data Sheet
Rev. G | Page 12 of 16
PRECISION CURRENT SINKS
00320-032
V+
200Ω
R1
1Ω
1W
R
L
IRF520
I
O
V
IN
OP77
I
O
=
V
IN
> 0V
FULL SCALE OF 1V.
I
O
= 1A/V
V
IN
R1
Figure 31. Positive Current Sink
00320-033
200Ω
R
L
R1
IRF520
I
O
V
IN
V–
OP77
I
O
=
V
IN
> 0V
V
IN
R1
Figure 32. Positive Current Source
The simple high-current sinks, shown Figure 31 and Figure 32,
require the load to float between the power supply and the sink.
In these circuits, the high gain, high CMRR, and low TCV
OS
of
the OP77 ensure high accuracy.
The high gain and low TCV
OS
ensure accurate operation with
inputs from microvolts to volts. In Figure 33, the signal always
appears as a common-mode signal to the op amps. The
OP77EZ CMRR of 1 µV/V ensures errors of less than 2 ppm.
00320-035
+15V
–15V
1kΩ 1kΩ
R3
2kΩ
C1
30pF
D1
1N4148
7
6
4
2
3
0.1µF
0.1µF
2N4393
V
IN
+15V
V
OUT
0 < V
OUT
< 10V
D2
–15V
7
6
4
2
3
0.1µF
0.1µF
OP77E
OP77E
Figure 33. Precision Absolute Value Amplifier
00320-036
100Ω
V
OUT
15V
0.1µF
OP77
100Ω
100Ω
10µF
6
4
REF-01
V
O
2
6
4
REF-01
V
O
2
6
4
REF-01
V
O
2
+
Figure 34. Low Noise Precision Reference
