AL8820

Document number: DS37369 Rev. 1 - 2

9 of 15

www.diodes.com

December 2014

© Diodes Incorporated

AL8820

Set ratio of

)

( peak

L

L

I

I

K





3

1

1

3

1

((

1.5) 0.6 1.4) (2

)

10

1.5

5

32

-

=

44 (2

)

10

, 0

1.5

COMP

IN

COMP

LED

LED

SET

IN

COMP

LED

LED

V

K

V

V

V

V

V

I

K

R

KV

V

V

V

V

I

K

















 

 

















 

 













（1 ）

（1- ）

4

1

1

2

10

=

(2

)

LED

LED

SET

HYS

IN

V

I

K R

R

VK







 





 

When the value of K,

order to get appropriate efficiency and Electronic Transformer (ET) compatibility, generally K is set between 0.4 and 0.8. Due to the range of

Step-Up Converter Inductor Selection

Because of the using of the hysteretic control scheme, the switching frequency in a boost configuration can be adjusted in accordance to the value

of the inductor being used. The value of the inductor can be determined by using the following equation:

1

)

(

1

1

)

(

1

1

)

(

1

1

1

]

)

2

2

(

[

]

)

(

[

]

)

(

[

2

SW

ave

L

DSON

L

SET

F

IN

L

ave

L

SET

L

F

IN

IN

ave

L

DSON

L

SET

IN

f

I

R

R

R

V

V

I

I

R

R

V

V

V

I

R

R

R

V

L





































Where:

L2 is the coil inductance.