LP3954 Datasheet, PDF (26/60 Pages) National Semiconductor (TI) – Advanced Lighting Management Unit

LP3954
SNVS340D – JUNE 2005 – REVISED MARCH 2013
Figure 24 shows the functionality of the built-in flash.
Current
HC[1:0] = 11
VIEW FINDER / FOCUS
HC[1:0] = 10
HC[1:0] = 01
HC[1:0] = 00
HC[1:0]
FLASH_EN input
HIGH CURRENT
FLASH
FL_T[1:0]
HC[11] = IMAX
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For mode _Time
FL_T[1:0]=11
EN_HCFLASH bit
Figure 24. Built-In Flash
HIGH CURRENT DRIVER ELECTRICAL CHARACTERISTICS
I_LEAKAGE
I_MAX(FLASH)
Parameter
FLASH pin leakage current
Maximum Sink Current
Accuracy at 300 mA
Current mirror ratio
Test Conditions
R_FLASH=1.18 kΩ ±1%
Min
Typ
Max
Unit
0.1
2
µA
400
mA
±5
±10
%
1:300
Backlight Drivers
LP3954 has 2 independent backlight drivers. Both drivers are regulated constant current sinks. LED current for
both LED banks (WLED1…4 and WLED5…6) are controlled by 8-bit current mode DACs with 0.1 mA step.
WLED1…4 and WLED5…6 can be also controlled with one DAC for better matching allowing the use of larger
displays having up to 6 white LEDs in parallel.
Display configuration is controlled with DISPL bit as shown below.
DISPL
0
1
Configuration
Main display up to 4 LEDs
Sub display up to 2 LEDs
Large display up to 6 LEDs
Matching
Good btw WLED1…4
Good btw WLED5…6
Good btw WLED 1…6
Display backlight enables
EN_W1-4
EN_W5-6
1
WLED1-4 enabled
0
WLED1-4 disabled
1
WLED5-6 enabled
0
WLED5-6 disabled
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