4

Typical Applications

The user is cautioned that, due to extremely high input

impedances, care must be exercised in layout, construction,

board cleanliness, and supply filtering to avoid hum and

noise pickup.

FIGURE 1. SIMPLE FOLLOWER

FIGURE 2. LEVEL DETECTOR

FIGURE 3. PHOTOCURRENT INTEGRATOR

FIGURE 4. TRIANGLE/SQUARE WAVE GENERATOR

FIGURE 5. AVERAGING AC TO DC CONVERTER FOR A/D

CONVERTERS SUCH AS ICL7106, ICL7107,

ICL7109, ICL7116, ICL7117

FIGURE 6. BURN-IN AND LIFE TEST CIRCUIT

ICL76XX

+

-

ICL76XX

+

-

100k

Ω

+5

+5

1M

Ω

TO CMOS OR

LPTTL LOGIC

1

µF

ICL76XX

+

-

+

λ

NOTE: Low leakage currents allow integration times up to

several hours.

1M

Ω

+

-

1M

Ω

DUTY CYCLE

V-

V+

680k

Ω

1M

Ω

WAVEFORM GENERATOR

+

-

1/2

ICL7621

1/2

ICL7621

NOTE: Since the output range swings exactly from rail to rail, fre-

quency and duty cycle are virtually independent of power supply

variations.

10

µF

1/2

+

-

20k

Ω

20k

Ω

1M

Ω

2.2M

Ω

COMMON

10k

Ω

0.5

µF

1.8k = 5%

SCALE

ADJUST

TO

SUCCEEDING

INPUT

STAGE

+

-

ICL7621

1/2

ICL7621

+

OUT

V+

V+

-8V

+8V

ICL7621