OP77_02 Datasheet, PDF (12/16 Pages) Analog Devices – Next Generation OP07 Ultralow Offset Voltage Operational Amplifier

OP77
R5 + R4
R2
must =
R3
R1
Precision Current Sinks
V_IN
200⍀
OP77
V+
R_L
I_O
IRF520
I_O
=
V_IN
R1
V_IN > OV
FULL SCALE OF 1V,
I_O = 1A/V
R1
1⍀
1W
Figure 11. Positive Current Sink
R1
OP77
200⍀
IRF520
V_IN
I_O
I_O
=
V_IN
R1
R_L
V_IN > OV
V–
Figure 12. Positive Current Source
These simple high-current sinks require the load to float between
the power supply and the sink.
In these circuits, OP77’s high gain, high CMRR, and low TCV_OS
ensure high accuracy.
2mA
1N4579A D1
6.4V ؎5%
؎5ppm/؇C
R1
1.8k⍀
15V
3
7
6
OP77
2
4
R2
3.6k⍀
E_O = 10V
R3
6.4k⍀
A_VCL 1.6
Figure 13. High Stability Voltage Reference
This simple bootstrapped voltage reference provides a precise 10 V
virtually independent of changes in power supply voltage, ambi-
ent temperature and output loading. Correct Zener operating
current of exactly 2 mA is maintained by R1, a selected 5 ppm/∞C
resistor, connected to the regulated output. Accuracy is prima-
rily determined by three factors: the 5 ppm/∞C temperature
coefficient of D1, 1 ppm/∞C ratio tracking of R2 and R3, and
operational amplifier V_OS errors.
VOs errors, amplified by 1.6 (AVCL), appear at the output and
can be significant with most monolithic amplifiers. For example,
an ordinary amplifier with TCV_OS of 5 mV/∞C contributes 0.8 ppm/
∞C of output error while the OP77, with TCV_OS of 0.3 mV/∞C,
contributes but 0.05 ppm/∞C of output error, thus effectively
eliminating TCV_OS as an error consideration.
The high gain and low TCV_OS assure accurate operation with
inputs from microvolts to volts. In this circuit, the signal always
1k⍀
1k⍀
+15V
+15V
0.1␮F
C1
30pF
D1
1N4148
0.1␮F
2
7
2
7
6
OP77E
3
V_IN
4
0.1␮F
D2
2N4393
R3
2k⍀
6
OP77E
3
4
0.1␮F
V_OUT
0 < V_OUT < 10V
–15V
–15V
Figure 14. Precision Absolute Value Amplifier
The high gain and low TCV_OS assure accurate operation with
inputs from microvolts to volts. In this circuit, the signal always
appears as a common-mode signal to the op amps. The OP77E
CMRR of 1 ␮V/V assures errors of less than 2 ppm.
–12–
REV. C