TL081C,AC TL082C,AC TL084C,AC

6

MOTOROLA ANALOG IC DEVICE DATA

–

+

–

+

Reset

Vin

1/2

TL082

1N914

1.0

µF

*

*Polycarbonate or

Polystyrene Capacitor

VO

Figure 14. Positive Peak Detector

VR

Run

R4

R1

V1

R3

TL081

6

R6

Clear

C*

R5

–

+

*Polycarbonate or

Polystyrene Capacitor

Time (t) = R4 C n (VR/VR–VI), R3 = R4, R5 = 0.1 R6

If R1 = R2: t = 0.693 R4C

Design Example: 100 Second Timer

VR = 10 V

C = l.0 mF

R3 = R4 = 144 M

R6 = 20 k

R5 = 2.0 k

R1 = R2 = 1.0 k

R2

Figure 15. Voltage Controlled Current Source

Figure 16. Long Interval RC Timer

R2 5.1 k

VO

R1 5.1 k

TL081

RL 5.1 k

CL 0.5 µF

CC 20 pF

R3 10

2.0 V

0

V/

µs = 0.04 V/µs (with CL shown)

• Overshoot t 10%

• ts = 10 µs

• When driving large CL, the VO slew rate is determined by CL

–2.0 V

IO

Figure 17. Isolating Large Capacitive Loads

If R1 through R4 > > R5 then Iout =

+

Vin

R1

R5

R2

TL081

R4

IO

–

1/2

TL082

–

+

V

in

R5

DV

O

Dt +

I

O

C

L

^ 0.02

0.5

R3