REV. C

OP77

–10–

50

200k

4000

=

OP77

Figure 1. Typical Offset Voltage Test Circuit

100

2.5M

VO

INPUT REFERRED NOISE

25,000

=

2

3

7

4

6

3.3k

4.7 F

10Hz FILTER)

(

V+

V–

OUTPUT

100

OP77

Figure 2. Typical Low-Frequency Noise Test Circuit

20k

2

3

7

4

6

V–

OUTPUT

INPUT

V+

+

–

1

8

OP77

Figure 3. Optional Offset Nulling Circuit

2

3

7

4

6

100k

+18V

10

10 F

0.1 F

10

OP77

0.1 F

10k

10k

10 F

–18V

1 PER BOARD

+

+

*

*

*

Figure 4. Burn-In Circuit

1M

10

100k

10k

–10V

+10V

0V

~

TYPICAL

PRECISION OP AMP

NOTES

1. GAIN NOT CONSTANT. CAUSES NONLINEAR ERRORS.

3. CHECK THE OP AMP PERFORMANCE, ESPECIALLY AT TEMPERATURES.

Figure 5. Open-Loop Gain Linearity

Actual open-loop voltage gain can vary greatly at various output

voltages. All automated testers use endpoint testing and therefore

only show the average gain. This causes errors in high closed-

loop gain circuits. Since this is so difficult for manufacturers to

test, users should make their own evaluation. This simple test

circuit makes it easy. An ideal op amp would show a horizontal

scope trace.

–10V

+10V

0V

~

Figure 6. Output Gain Linearity Trace

This is the output gain linearity trace for the new OP77. The

output trace is virtually horizontal at all points, assuring extremely

high gain accuracy. The average open-loop gain is truly impres-

sive—approximately 10,000,000.