Datasheet

LED
ON SW
BU
O
CK
N
ON OFF
t
t
V
D t f
V t
u

I
COLL
V+
BR1
VAC
TRIAC
DIMMER
+
+
9
10
11
12
13 4
5
6
7
8
-
V
LED
BLDR
ASNS
ISNS
DIM
COFF
GND
VCC
FLTR1
GND
FLTR2
LM3448
V
LED-
D3
C7
C9
C10
D4
D8
D9
R2
D1
Q1
C5
R5
C12
D2
D10
L2
Q3
R3
R4
C11
R1
U1
V
BUCK
14 3
NC
NC
C4
C3
15 2
SW
SW
16 1
SW
SW
LM3448
www.ti.com SNOSB51C –SEPTEMBER 2011–REVISED MAY 2013
Design Guide
Figure 33. Typical Non-Isolated Buck Converter with Valley-Fill PFC
The following design guide is an example of how to design the LM3448 as a non-isolated buck converter with
valley-fill PFC as shown in Figure 19.
DETERMINING DUTY-CYCLE (D)
Duty cycle (D) approximately equals:
(4)
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