LM3424 Datasheet, PDF (10/69 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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Typical Characteristics (continued)
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).
100.3
1M
100.1
99.9
99.7
100k
10k
99.5
-50
R_GAIN = 10 kΩ
-14
22
58
94
TEMPERATURE (°C)
V_TSENSE = 0.5 V
130
V_TREF = 1.5 V
Figure 13. I_TF vs. Junction Temperature
1.25
1.00
0.75
0.50
RGAIN = 5 k:
RGAIN = 15 k:
0.25
RGAIN = 10 k:
0.00
0
25
50
75 100 125
TEMPERATURE (°C)
R_REF1 = R_REF2 = 49.9 kΩ
R_NTC-BK = R_BIAS = 43.2 kΩ
Figure 15. Ideal Thermal Foldback with Varied Slope
1k
10k
100k
1M
f_SW (Hz)
10M
Figure 14. Switching Frequency vs. Timing Resistance
1.25
1.00
RBIAS = 24.3 k:
0.75
0.50
RBIAS = 84.5 k:
0.25
RBIAS = 43.2 k:
0.00
0
25
50
75 100 125
TEMPERATURE (°C)
R_REF1 = R_REF2 = 49.9 kΩ
R_GAIN = 10 kΩ
Figure 16. Ideal Thermal Foldback with Varied Breakpoint
10
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