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]

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[2:0]

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.

RSW1

GSW1

BSW1

RSW2

GSW2

BSW2

Enable for R1 switch

Enable for G1 switch

Enable for B1 switch

Enable for R2 switch

Enable for G2 switch

Enable for B2 switch

RGB_START

Master Switch for both RGB drivers:

RGB_START = 0

→ RGB OFF

RGB_START = 1

→ RGB ON, starts the new cycle fromt=0

RGB_PWM

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)

EN_FLASH

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.

R1_PWM

G1_PWM

B1_PWM

R2_PWM

G2_PWM

B2_PWM

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

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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