LP8557 Datasheet, PDF (9/49 Pages) Texas Instruments – High-Efficiency LED Backlight Driver For Tablets

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LP8557, LP85571
SNVSA15B – DECEMBER 2013 – REVISED DECEMBER 2015
Typical Characteristics (continued)
Unless otherwise specified: V_IN = V_DD = 3.8 V, L = 10 µH Cyntec PIME051E, D = Diodes PD3S130L-7, C_OUT = 2 × 4.7 µF,
LED V_ƒ = 2.85 V (typical), I_{LED_MAX} = 25 mA per string.
90
90
88
88
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86
84
84
82
80
0
3p9s
3p7s
3p5s
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40
60
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100
Brightness [%]
C001
82
80
0
3p8s
3p6s
3p4s
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40
60
80
100
Brightness [%]
C001
Figure 8. LED Efficiency With 3 LED Strings
90
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0
2p8s
2p6s
2p4s
20
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Brightness [%]
C001
Figure 9. LED Efficiency With 3 LED Strings
90
88
86
84
82
80
0
2p9s
2p7s
2p5s
20
40
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80
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Brightness [%]
C001
Figure 10. LED Efficiency With 2 LED Strings
90
88
86
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1p9s
1p7s
1p5s
20
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60
80
100
Brightness [%]
C001
Figure 11. LED Efficiency With 2 LED Strings
90
88
86
84
82
80
0
1p8s
1p6s
1p4s
20
40
60
80
100
Brightness [%]
C001
Figure 12. LED Efficiency With 1 LED String
Figure 13. LED Efficiency With 1 LED String
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