LP3954 Datasheet, PDF (26/56 Pages) National Semiconductor (TI) – Advanced Lighting Management Unit

ADJUSTMENT
WLED1-4[7:0]
WLED5-6[7:0]
0000 0000
0000 0001
0000 0010
0000 0011
…
…
1111 1101
1111 1110
1111 1111
Driver current,
ma (typical)
0
0.1
0.2
0.3
…
…
25.3
25.4
25.5
WLED Output Current vs. Voltage
FADE IN / FADE OUT
LP3954 has an automatic fade in and out for main and sub
backlight. The fade function is enabled with EN_FADE bit.
The slope of the fade curve is set by the SLOPE bit. Fade
control for main and sub display is set by FADE_SEL bit.
EN_FADE
0 Automatic fade disabled
1 Automatic fade enabled
SLOPE
0 Fade execution time 1.3s
1 Fade execution time 0.65s
FADE_SEL
0 Fade controls WLED1-4
1 Fade controls WLED5-6
Note: if DISPL=1 and FADE_SEL=0, Fade effects to WLED1-6
Recommended fading sequence:
1. ASSUMPTION: Current WLED value in register
2. Set SLOPE
3. Set FADE_SEL
4. Set EN_FADE = 1
5. Set target WLED value
6. Fading will be done either within 0.5s or 1s based on
Slope selection
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WLED dimming, SLOPE=0
WLED dimming, SLOPE=1
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