LP3954 Datasheet, PDF (15/60 Pages) National Semiconductor (TI) – Advanced Lighting Management Unit

LP3954
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CC_RGB1
CC_RGB2
r1sw
g1sw
b1sw
r2sw
g2sw
b2sw
SNVS340D – JUNE 2005 – REVISED MARCH 2013
Table 2. RGB_ctrl Register (00H)
1 R1, G1 and B1 are switches → limit current with ballast resistor
bit7
0 R1, G1 and B1 are constant current sinks, current limited internally
1 R2, G2 and B2 are switches → limit current with ballast resistor
bit6
0 R2, G2 and B2 are constant current sinks, current limited internally
1 R1 is on
bit5
0 R1 is off
1 G1 is on
bit4
0 G1 is off
1 B1 is on
bit3
0 B1 is off
1 R2 is on
bit2
0 R2 is off
1 G2 is on
bit1
0 G2 is off
1 B2 is on
bit0
0 B2 is off
R1 ^RR1
V_OUT
V_OUT
R1
R1
control
RR2
G1 RG1
R1
control
G1
G1
control
RG2
B1
RB1
RB2
B1
control
RGB1 output as switch (SW)
G1
control
B1
B1
control
RGB1 output as a constant
current sink (CC)
Command Based Pattern Generator for Color LEDs
The LP3954 has a unique stand-alone command based pattern generator with 8 user controllable 16-bit wide
commands. Since write registers are 8-bit long one command requires 2 write cycles. Each command has
intensity level for each LED, command execution time (CET) and transition time (TT). The command structure is
shown in following two figures.
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