V+

VAC

+

+

1

2

3

4

5

6

7

8

9

1

0

-

G

N

D

VC

C

FILT

ER

NC

NC

ISN

S

GAT

E

NC

CO

FF

N

C

LM344

4

D

3

C

7

C

9

C

1

0

D

4

D

8

D

9

R

2

D

1

Q

1

C

5

C

1

2

D2

D1

0

Q2

L

2

Q3

R

3

R

4

C

1

1

C

4

U1

BR1

LM3444

www.ti.com

SNVS682B – NOVEMBER 2010 – REVISED NOVEMBER 2011

APPLICATION INFORMATION

FUNCTIONAL DESCRIPTION

The LM3444 contains all the necessary circuitry to build a line-powered (mains powered) constant current LED

driver.

Theory of Operation

Refer to Figure 11 below which shows the LM3444 along with basic external circuitry.

Figure 11. LM3444 Schematic

VALLEY-FILL CIRCUIT

capacitors are being charged. However, the network of diodes and capacitors shown between D3 and C10 make

up a "valley-fill" circuit. The valley-fill circuit can be configured with two or three stages. The most common

configuration is two stages. Figure 12 illustrates a two and three stage valley-fill circuit.

Copyright © 2010–2011, Texas Instruments Incorporated

Submit Documentation Feedback

7

Product Folder Links: LM3444