LM3450 Datasheet, PDF (13/40 Pages) National Semiconductor (TI) – LED Driver with Active Power Factor Correction and Phase Dimming Decoder

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i
I_S-PK
LM3450
SNVS681D – NOVEMBER 2010 – REVISED MAY 2013
I_P-PK
I_IN-PK
t_ON
T_SW
t
Figure 20. CRM Flyback Current Waveforms
Rectified AC
R_AC2
R_AC1
LM3450/50A
V_AC
1/3
COMP
Multiplier
LOGIC
C_CMP
R_FB1
FB
R_FB2
OPTO
(Isolated)
V_OUT
(Non-
isolated)
50 P$
2.7V
-
2.5V +
5V
5 k:
346mV +
-
168mV +
-
Error Amp
Disable
Shutdown
+
3V -
OVP
ZCD
-
+ 1.5V
GATE
R_ZCD
CS
GND
Figure 21. PFC Control Circuit
L
Q_SW
R_CS
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