ICL8038
Test Circuit
+10V
R
A
10K
7
SW
1
N.C.
8
ICL8038
3
R
TRI
10
C
3300pF
11
12 2
82K
R
SINE
-10V
4
5
R
B
10K
6
9
R
L
10K
FIGURE 1. TEST CIRCUIT
Detailed Schematic
CURRENT SOURCES
R
EXT
B
Q
1
Q
2
5
Q
3
Q
4
Q
7
R
46
40K
Q
10
R
3
30K
Q
30
Q
31
Q
32
Q
33
Q
34
Q
24
9
R
11
270
Q
23
R
12
2.7K
Q
25
R
13
620
R
16
1.8K
R
14
27K
Q
26
R
15
470
Q
29
Q
Q
27 28
R
17
4.7K
R
18
4.7K
FLIP-FLOP
Q
35
R
41
27K
Q
37
Q
36
Q
38
Q
40
R
43
27K
Q
39
3 R
44
1K
R
4
100
Q
11
Q
12
Q
13
R
5
100
R
6
100
Q
19
Q
5
COMPARATOR
Q
8
Q
9
10
Q
15
C
EXT
R
7B
15K
Q
20
Q
21
Q
22
R
10
5K
Q
49
R
22
10K
R
23
2.7K
R
24
800
R
28
33K
Q
50
Q
51
Q
52
Q
53
Q
54
Q
55
Q
56
R
42
BUFFER AMPLIFIER
27K
11
2
SINE CONVERTER
R
38
375
R
39
200
R
40
5.6K
R
37
330
R
29
33K
R
30
33K
R
31
33K
Q
16
Q
17
R
7A
10K
Q
18
R
9
5K
R
EXT
A
4
Q
14
R
8
5K
Q
47
Q
46
Q
45
Q
44
Q
43
Q
42
R
25
33K
R
26
33K
R
27
33K
R
45
33K
R
41
4K
Q
48
R
19
800
R
20
2.7K
R
21
10K
Q
41
R
33
200
R
34
375
R
35
330
6
V+
R
32
5.2K
1
R
1
8
11K
7
R
2
Q
39K
6
R
36
1600
12
R
EXT
C
82K
Application Information
(See Functional Diagram)
An external capacitor C is charged and discharged by two cur-
rent sources. Current source #2 is switched on and off by a flip-
flop, while current source #1 is on continuously. Assuming that
the flip-flop is in a state such that current source #2 is off, and
the capacitor is charged with a current I, the voltage across the
capacitor rises linearly with time. When this voltage reaches the
level of comparator #1 (set at 2/3 of the supply voltage), the flip-
flop is triggered, changes states, and releases current source
#2. This current source normally carries a current 2I, thus the
capacitor is discharged with a net-current I and the voltage
across it drops linearly with time. When it has reached the level
of comparator #2 (set at 1/3 of the supply voltage), the flip-flop
is triggered into its original state and the cycle starts again.
Four waveforms are readily obtainable from this basic gener-
ator circuit. With the current sources set at I and 2I respec-
tively, the charge and discharge times are equal. Thus a
triangle waveform is created across the capacitor and the
flip-flop produces a square wave. Both waveforms are fed to
buffer stages and are available at pins 3 and 9.
8-156
HARRIS [ HARRIS CORPORATION ]
