2007. 2. 26

5/7

KAB3403T/DN

Revision No : 0

4. Using a Logic Signal to FB pin.

For application that need to adjust the LED current in discrete

steps. A logic signal can be used as shown in Figure 9.

Figure9. Using a Logic Signal to FB pin.

GND

SW

C1

C2

R1

R2

D1

CTL

FB

OVD

1

µF

1

µF

LED1

LED2

LED3

LED4

L1

4.7

µH ~ 22µH

L1

4.7

µH ~ 22µH

SW

C1

1

µF

C2

1

µF

D1

CTL

FB

OVD

LED1

LED2

LED3

LED4

GND

R1

16

Ω

DC

KAB3403T/DN

GND

SW

C3

C2

R1

1

5kΩ

D1

CTL

FB

OVD

1

µF

1

µF

LED1

LED2

LED3

LED4

PWM

Signal

L1

4.7

µH ~ 22µH

C1

1

µF

KAB3403T/DN

KAB3403T/DN

GND

SW

C1

C2

R1

D1

CTL

FB

OVD

1

µF

1

µF

LED1

LED2

LED3

LED4

KTK5132V

LOGIC

L1

4.7

µH ~ 22µH

KAB3403T/DN

Figure6. Using a DC Signal to CTL pin.

2. Using a filtered PWM Signal to CTL pin.

The filtered PWM signal can be considered as an adjustable DC

voltage. It can be used to replace the variable DC Voltage source

in dimming control. The circuit is shown in Figure 7

Figure7. Using a filtered PWM Signal to CTL pin.

3. Using a DC Voltage to FB pin.

The dimming control using a DC control voltage to FB pin of the

KAB3403T/DN is shown in Figure. The LED current can be

varied applying a DC voltage to the FB pin. The voltage can come

from a filtered PWM signal. It can be used to replace the variable

DC voltage source in dimming control.