4-167

TELCOM SEMICONDUCTOR, INC.

7

6

5

4

3

1

2

8

TC96C555

3A OUTPUT PROGRAMMABLE

POWER OSCILLATOR

APPLICATIONS (Cont.)

Figure 8. Frequency vs Control

Duty Cycle vs. Charge Current

Frequency in kHz

10

30

50

70

90

Charge Current in

µA

ISINK = 100µA

100

80

60

40

20

0

20

40

60

80

100

16

38

50

16

38

Figure 6. Duty Cycle vs. Charge Current

Voltage Controlled Oscillator

RCHG = 51k, Rdis = 25.5k

3.25V

5V

Control Voltage

1000K

100K

10K

1K

100

10

4V

7V

3.5V

0.1

µF

1000pF

100pF

10pF

0.01

µF

Figure 7. Voltage Controlled Power Oscillator

VREF

VR1

VIN

VR2

1

3

TC96C555

VDD

GND

C

2

4

OUTPUT

+12V

8

.1

µF

OUT

OUT

7

6

RCHG

RDIS

CONTROL

VOLTAGE

SOURCE

voltage source instead of connecting to the 4V reference of

Pin 3, one can increase or decrease the output frequency.

Increasing the voltage source to 5V will double the oscillator

frequency in half.