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180 190 200 210 220 230 240 250 260
50
150
250
350
450
550
650
LED CURRENT (mA)
INPUT VOLTAGE (V
RMS
)
4 LEDs
8 LEDs
10 LEDs
6 LEDs
180 190 200 210 220 230 240 250 260
100
150
200
250
300
350
400
450
500
550
600
LED CURRENT (mA)
INPUT VOLTAGE (V
RMS
)
Mod C (10 LEDs)
Mod B (8 LEDs)
Original (6 LEDs)
Mod A (4 LEDs)
180 190 200 210 220 230 240 250 260
0.78
0.80
0.82
0.85
0.87
EFFICIENCY
INPUT VOLTAGE (V
RMS
)
10 LEDs
8 LEDs
6 LEDs
4 LEDs
180 190 200 210 220 230 240 250 260
0.60
0.64
0.68
0.73
0.77
0.81
0.85
0.89
0.93
0.97
EFFICIENCY
INPUT VOLTAGE (V
RMS
)
Mod B (8 LEDs)
Mod C (10 LEDs)
Mod A (4 LEDs)
Original (6 LEDs)
www.ti.com Typical Performance Characteristics
12 Typical Performance Characteristics
Original Circuit (6 LEDs operating at 350mA): R21 = 2.7Ω; Modification A (10 LEDs operating at 375mA):
R21 = 1.8Ω; Modification B (8 LEDs operating at 350mA): R21 = 2.2Ω; Modification C (4 LEDs operating
at 315mA): R21 = 3.9Ω
The output power can be varied to achieve desired LED current by interpolating R21 values between the
maximum of 3.9 Ω and minimum of 1.8 Ω
The maximum output voltage is clamped to 36 V. For operating LED string voltage > 36 V, replace D6
with suitable alternative
Figure 5. Efficiency vs. Line Voltage Figure 6. Efficiency vs. Line Voltage
Original Circuit Modified Circuits
Figure 7. LED Current vs. Line Voltage Figure 8. LED Current vs. Line Voltage
Original Circuit Modified Circuits
9
SNVA462F–November 2010–Revised May 2013 AN-2097 LM3444 - 230VAC, 8W Isolated Flyback LED Driver
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