FAN8902(KA3902)

7

4. Oscillator Component Selection

The oscillator timing components can be calculated as follows:

For example, if fosc = 25kHz and duty = 95%

5. Current Command Input Section

Vref

Logic

+

−

T=40.0

Td=1.0

t [

µs]

T

C

R

T

C

T

×

In Vref

V

L

–

() Vref V

H

–

()

⁄

[]

×

=

T

D

C

T

V

H

V

L

–

() I

D

⁄

[]

×

=

fosc

1

T

C

T

D

+

()

⁄

=

1.875

R

T

C

T

×

()

⁄

=

Duty

T

C

fosc

×

100

×

=

C

T

T

D

I

D

×

() V

H

V

L

–

()

⁄

=

1000 pF

[]

=

R

T

1.875

fosc

C

T

×

()

⁄

=

1.875

25kHz

1000pF

×

()

⁄

=

75 k

Ω

[]

=

+

−

+

−

+

14

1

CMD

La

4R

R

Logic

I*

FAN8902