SNVS682C – NOVEMBER 2010 – REVISED MAY 2013
AC-DC Offline LED Driver
Check for Samples:
1
FEATURES
Application Voltage Range 80V
AC
– 277V
AC
Capable of Controlling LED Currents Greater
than 1A
Adjustable Switching Frequency
Low Quiescent Current
Adaptive Programmable Off-time Allows for
Constant Ripple Current
Thermal Shutdown
No 120Hz Flicker
Low Profile 10-Pin VSSOP Package or 8-Lead
SOIC Package
Patent Pending Drive Architecture
DESCRIPTION
The LM3444 is an adaptive constant off-time AC/DC
buck (step-down) constant current controller that
provides a constant current for illuminating high
power LEDs. The high frequency capable architecture
allows the use of small external passive components.
A passive PFC circuit ensures good power factor by
drawing current directly from the line for most of the
cycle, and provides a constant positive voltage to the
buck regulator. Additional features include thermal
shutdown, current limit and V
CC
under-voltage
lockout. The LM3444 is available in a low profile 10-
pin VSSOP package or an 8-lead SOIC package.
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APPLICATIONS
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Solid State Lighting
Industrial and Commercial Lighting
Residential Lighting
TYPICAL LM3444 LED DRIVER APPLICATION CIRCUIT
V+
D
3
C
7
BR1
R
2
Q
1
VAC
D
1
D
4
+
D
8
D
9
C
9
V
BUCK
95.0
14 Series connected LEDs
C
1
+ 0
D2
D1
0
V
LED-
EFFICIENCY (%)
C
1
2
V
LED
-
R
4
90.0
85.0
10 Series connected LEDs
80.0
C
5
Q3
L
2
LM344
4
1 NC
U1
NC
VC
C
GAT
E
ISN
S
G
N
D
1
0
I
COLL
9
75.0
80
90
100
110
120
130
140
2 NC
N
C
CO
FF
FILT
ER
LINE VOLTAGE (V
AC
)
3
8
Q2
4
7
R
3
5
C
4
6
C
1
1
1
2
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Copyright © 2010–2013, Texas Instruments Incorporated
PRODUCTION DATA information is current as of publication date.
Products conform to specifications per the terms of the Texas
Instruments standard warranty. Production processing does not
necessarily include testing of all parameters.
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