LM3424 Datasheet, PDF (8/69 Pages) National Semiconductor (TI) – Constant Current N-Channel Controller with Thermal Foldback for Driving LEDs

LM3424, LM3424-Q1
SNVS603C – AUGUST 2009 – REVISED AUGUST 2015
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6.7 Typical Characteristics
T_A=25°C and V_IN = 14 V unless otherwise specified. The measurements for Figure 1, Figure 3, andFigure 6 were made using
the standard boost evaluation board from AN-1969 (SNVA397). The measurements for Figure 2, Figure 4, and Figure 5 were
made using the standard buck-boost evaluation board from AN-1967 (SNVA398).
100
95
90
85
80
10
15
20
25
30
V_IN (V)
V_O = 32 V (9 LEDs)
Figure 1. Boost Efficiency vs Input Voltage
1.010
100
95
90
85
80
75
70
0
16
32
48
64
80
VIN (V)
V_O = 21 V (6 LEDs)
Figure 2. Buck-Boost Efficiency vs. Input Voltage
1.02
1.005
1.01
1.000
1.00
0.995
0.99
0.990
5
10
15
20
25
30
VIN (V)
V_O = 32 V (9 LEDs)
Figure 3. Boost LED Current vs. Input Voltage
1.0
0.8
0.6
0.4
0.2
0.0
0
20
40
60
80 100
ICSH (éA)
V_O = 21 V (6 LEDs)
Figure 5. Analog Dimming
V_IN = 24 V
0.98
0
16
32
48
64
80
VIN (V)
V_O = 21 V (6 LEDs)
Figure 4. Buck-Boost LED Current vs. Input Voltage
1.0
0.8
0.6
1 kHz
0.4
25 kHz
0.2
0.8
0
20
40
60
80 100
DUTY CYCLE (%)
V_O = 32V (9 LEDs)
Figure 6. PWM Dimming
V_IN = 24 V
8
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