LP5018 datasheet(13/59 Pages) TI1

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7.3 Feature Description

7.3.1 PWM Control for Each Channel

Most traditional LED drivers are designed for the single-color LEDs, in which the high-resolution PWM generator

is used for intensity control only. However, for RGB LEDs, both the color mixing and intensity control should be

addressed to achieve the target effect. With the traditional solution, the users must handle the color mixing and

intensity control simultaneously with a single PWM register. Several undesired effects occur: the limited dimming

steps, the complex software design, and the color distortion when using a logarithmic scale control.

The LP50xx device is designed with independent color mixing and intensity control, which makes the RGB

LED effects fancy and the control experience straightforward. With the inputs of the color-mixing register and

the intensity-control register, the final PWM generator output for each channel is 12-bit resolution and 29kHz

dimming frequency, which helps achieve a smooth dimming effect and eliminates audible noise. See Figure 7-1.

OUT0

8 Bits Color

8 Bits Brightness

Color-Mixing

Brightness-Control

12 Bits / 29KHz PWM

PWM Generators

OUT1

OUT2

OUT21

OUT22

OUT23

Figure 7-1. PWM Control Scheme for Each Channel

7.3.1.1 Independent Color Mixing Per RGB LED Module

Each output channel has its own individual 8-bit color-setting register (OUTx_COLOR). The device allows every

RGB LED module to achieve >16 million (256 × 256 × 256) color-mixing.

7.3.1.2 Independent Intensity Control Per RGB LED Module

When color is fixed, the independent intensity-control is used to achieve accurate and flexible dimming control

for every RGB LED module.

7.3.1.2.1 Intensity-Control Register Configuration

Every three consecutive output channels are assigned to their respective intensity-control register

(LEDx_BRIGHTNESS). For example, OUT0, OUT1, and OUT2 are assigned to LED0_BRIGHTNESS, so it

is recommended to connect the RGB LEDs in the sequence as shown in LED Bank Control. The LP50xx device

allows 256-step intensity control for each RGB LED module, which helps achieve a smooth dimming effect.

Keeping FFh (default value) in the LED0_BRIGHTNESS register results in 100% dimming duty cycle. With this

setting, users can just configure the color mixing register by channel to achieve the target dimming effect in a

single-color LED application.

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LP5018, LP5024

SLVSEB8C – OCTOBER 2018 – REVISED JULY 2024

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