Datasheet

R20 C18
FLTR2
R3
R8
DIM
R16
C16
R2
R7
D5
Q1
R11
V+
C14
C15
V
CC
R13
D9
R22
R21
VLED+
VLED±
L1
C6
R6
V+
LINE
NEUTRAL
INPUT EMI FILTER AND RECTIFIER CIRCUIT
D1
D3
D4
D6
C12
DIM
V
CC
FLTR2
R18
C17
R17
TRIAC HOLDING
CIRCUIT
R23
C20
Q4
C2
C5
L2
R4
R12
C8
R5
D2
T1
C1
+
LM3448
9
10
11
12
13 4
5
6
7
8
BLDR
ASNS
ISNS
DIM
COFF
GND
VCC
FLTR1
GND
FLTR2
14
3NC
NC
15 2SWSW
16 1
SW
SW
COFF
COFF
R9
C7
COFF CURRENT
SOURCE
V
CC
V
AUX
R14
V
AUX
C11
Q3
OVP CIRCUIT
FLTR2
D11
V
AUX
Q2
VCC AUXILIARY BIAS CIRCUIT
R15
D10
D8
V
CC
VR1
F1
C9 C10
R10
C4
R1
C3
PGND SGND
D7
C13
LM3448
SNOSB51C –SEPTEMBER 2011–REVISED MAY 2013 www.ti.com
DESIGN #4: 6W, 230VAC Isolated Flyback LED Driver with Direct Line Injection
SPECIFICATIONS:
• AC Input Voltage: 230VAC nominal (180VAC – 265VAC)
• Flyback Output Voltage: 27.0V
DC
• LED Output Current: 226mA
This TRIAC dimmer compatible design incorporates the following features:
• Direct line-injection for improved power factor performance
• Standard V
CC
start-up with auxiliary winding bias circuit for improved system efficiency,
• V
CC
derived COFF current source,
• Additional TRIAC holding current circuit for improved dimmer performance at low conduction angles,
• Output overvoltage protection (OVP).
NOTE: Refer to LM3448 Application Note, AN-2091 (TI Lit Number SNOA555), for additional information and
BOM regarding this design.
Figure 42. DESIGN #4 Circuit
38 Submit Documentation Feedback Copyright © 2011–2013, Texas Instruments Incorporated
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