ICL8038 Datasheet, PDF(4/10 Page) Intersil Corporation – Precision Waveform Generator/Voltage Controlled Oscillator

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ICL8038 Datasheet, PDF (4/10 Pages) Intersil Corporation – Precision Waveform Generator/Voltage Controlled Oscillator

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ICL8038

Test Circuit

10K

SW1

N.C.

ICL8038

+10V

10K

RTRI

3300pF

12 2

82K

FIGURE 1. TEST CIRCUIT

RSINE

-10V

Detailed Schematic

CURRENT SOURCES

V+

R1 8

11K

3R92KQ6

REXT B

REXT A

Q14

R41

R46

40K

Q9 10

CEXT

30K

Q30

Q31

Q32

Q33

Q10

Q11

Q12

Q13

R5 R6

100

100 100

COMPARATOR

Q15

Q18

Q16Q17

R7B

R7A 5K

15K

10K

Q20 Q21

Q19

Q22

R10

Q34

Q23

R13 R16

620 1.8K

Q24

R11

270

Q26

R12

2.7K

R14

27K

Q27Q28

R15

470

Q25

Q29

FLIP-FLOP

R43

27K

Q35

Q37

Q39

R17

4.7K

R18

4.7K

Q36 Q38

R41

27K

Q40 3 R44

R42 BUFFER AMPLIFIER

27K

R32

5.2K

Q48

Q47

R19

Q46

800

R20

Q45

Q44

2.7K

R21

Q43

Q42

10K

Q41

R25

R26

R27

33K

R33

200

R34

375

R35

330

R45

33K

R36

1600

Q49

R22

10K

R23

2.7K

R24

800

R28

33K

Q50

Q51

R29

33K

Q52

Q53

R30

33K

Q54

Q55

R31

33K

R37

330

R38

375

R39

200

Q56

R40

5.6K

REXTC

82K

SINE CONVERTER

Application Information (See Functional Diagram)

An external capacitor C is charged and discharged by two

current 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

generator circuit. With the current sources set at I and 2I

respectively, the charge and discharge times are equal. Thus

a triangle waveform is created across the capacitor and the

ï¬ip-ï¬op produces a square wave. Both waveforms are fed to

buffer stages and are available at pins 3 and 9.

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