AL9910/AL9910A/AL9910-5

UNIVERSAL HIGH VOLTAGE HIGH BRIGHTNESS LED

DRIVER

AL9910/AL9910A/AL9910-5

Document number: DS 35103 Rev. 3 - 2

10 of 15

www.diodes.com

June 2011

© Diodes Incorporated

AC/DC Off-Line LED driver

The AL9910 is a cost-effective off-line buck LED driver-controller specifically designed for driving LED strings. It is suitable for

being used with either rectified AC line or any DC voltage between 15-500V. See figure 3 for typical circuit.

Fig. 3 Typical Application Circuit (without PFC)

Buck design equations:

=

D

IN

LEDs

V

V

osc

ON

f

D

t

=

≥

L

LED

ON

LEDs

IN

I

3

.

0

t

)

V

V

(

×

×

−

=

SENSE

R

))

3

.

0

I

(

5

.

0

(

I

25

.

0

LED

LED

×

×

+

Design example

voltage the duty cycle can be determined:

The value of the inductor is determined as follows:

R

SENSE

AL9910/A

GATE

CS

LD

PWM_D

GND

R

OSC

V

DD

V

IN

LED +

LED -

V

Q1

L1

D1

C1

R

OSC

C2

C3

BR1

R

SENSE

AL9910/A

GATE

CS

LD

PWM_D

GND

R

OSC

V

DD

V

IN

LED +

LED -

V

Q1

L1

D1

C1

R

OSC

C2

C3

BR1