Datasheet

V
AUX
Q2
R15
D10
D8
V
CC
R7
D5
Q1
R11
V+
C14 C15
R13
D9
LM3448
6VCC
R14
Q2
D7
R15
D10
D8
C13
T1
SW
VLED
+
VLED-
R2
V
CC
V
AUX
Design Guide www.ti.com
12.3 Bias Supplies and Capacitances
The bias supply circuits shown in Figure 30 and Figure 31 enables instant turn-on through Q1 while
providing an auxiliary winding for high efficiency steady state operation. The two bias paths are each
connected to VCC through a diode (D7, D9) to ensure the higher of the two is providing V
CC
current.
Figure 30. Bias Supply Circuits
Figure 31. Auxiliary Winding Bias Circuit
18
AN-2091 LM3448 - 230VAC, 6W Isolated Flyback LED Driver SNOA555C–April 2011–Revised May 2013
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