LP3950 Datasheet, PDF (18/31 Pages) National Semiconductor (TI) – Color LED Driver with Audio Synchronizer

RGB LED PWM Control (Note 17) (Continued)
ROFF[3:0]
GOFF[3:0]
BOFF[3:0]
ROFF[3:0]
GOFF[3:0]
BOFF[3:0]
CYCLE[2:0]
RSW1
GSW1
BSW1
RSW2
GSW2
BSW2
RGB_START
RGB_PWM
EN_FLASH
R1_PWM
G1_PWM
B1_PWM
R2_PWM
G2_PWM
B2_PWM
OFF sets the beginning time of the turn-off slope. Off-time is relative to blinking cycle length in the same
way as on-time.
If ON = 0, OFF = 0 and RGB_PWM = 1, then RGB outputs are continuously on (no blinking), the DUTY
setting controls the brightness and the SLOPE control is ignored.
If ON and OFF are the same, but not 0, RGB outputs are turned off.
CYCLE sets the blinking cycle: [000] for 0.25s, [001] for 0.5s, [010] for 1.0s, [011] for 2.0s. and [1XX] for
4.0s CYCLE effects to all RGB LEDs.
Enable for R1 switch
Enable for G1 switch
Enable for B1 switch
Enable for R2 switch
Enable for G2 switch
Enable for B2 switch
Master Switch for both RGB drivers:
RGB_START = 0 → RGB OFF
RGB_START = 1 → RGB ON, starts the new cycle from t = 0
RGB_PWM = 0 → RSW, GWS and BSW control directly the RGB outputs (on/off control only)
RGB_PWM = 1 → Normal PWM RGB functionality (duty, slope, on/off times, cycle)
Flash mode enable control for RGB1 and RGB2. In the flash mode (EN_FLASH = 1) RGB outputs are
PWM controlled simultaneously, not in 3-phase system as in the normal mode.
xx_PWM = 0 → External PWM control from PWM_LED pin is disabled
xx_PWM = 1 → External PWM control from PWM_LED pin is enabled
Internal PWM control (DUTY) can be used independently of external PWM control. External PWM has
the same effect on all enabled outputs.
PWM_LED input can be used as a direct on/off or PWM
brightness control for selected RGB outputs. For example it
can trigger the flash using a flash signal from the camera. If
PWM_LED input is not used, it must be tied to V_DDIO.
Note 17: The LP3933 shares the same pattern generator. Application Note
AN-1291, “Driving RGB LEDs Using LP3933 Lighting Management System”
contains a thorough description of the RGB driver functionality including
programming examples.
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