BLUE

GREEN

GCTRL

BCTRL

RCTRL

RED

BLUE

GREEN

Green Transition Delay

Blue Transition Delay

Red Transition Delay

RCTRL

GCTRL

BCTRL

GREEN

RED

BLUE

1/3

1/3

1/3

GREEN

RED

BLUE

1/3

1/3

1/3

LM3435

www.ti.com

SNVS724C – JUNE 2011 – REVISED MAY 2013

SEQUENTIAL MODE RGB TIMING

LM3435 is a sequential mode RGB driver dedicatedly designed for pico and portable projector applications. By

using this device, the system only require one power driver stage for three color LEDs. With LM3435, only single

LED can be enabled at any given time period and the DC-DC converter can quickly adjusts the output voltage to

an optimized level by controlling the current flowing into the respective LED channel. This approach minimizes

the power dissipation of the internal current regulator and effectively maximizes the system efficiency. Timing of

the RGB LEDs depends solely on the RCTRL, GCTRL and BCTRL inputs. The Timing Chart in below shows a

typical timing of two cycles of even RGB scan. In real applications, the RGB sequence is totally controlled by the

system or the video processor. It’s not mandatory to follow the simple RGB sequence, but for any change

Figure 20. RGB Control Signals Timing Chart

PRIORITIES OF LED CONTROL SIGNALS

The LM3435 does not support color overlapping mode operation. At any instant, only one LED will be enabled

even overlapping control signals applied to the control inputs. The decision logics of the device determine which

LED channel should be enabled in case overlapping control signals are detected at the control inputs. The

GREEN channel has the higher priority over BLUE channel and the RED channel has the lowest priority.

However, if a low priority channel is already turned on before the high priority channel control signal comes in,

the low priority channel will continue to take the control until the control signal ceased. The timing diagram in

below illustrates some typical cases during operation.

Figure 21. Priorities of LED Control Signals

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