LP5018 datasheet(14/59 Pages) TI2

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7.3.1.2.2 Logarithmic- or Linear-Scale Intensity Control

For human-eye-friendly visual performance, a logarithmic-scale dimming curve is usually implemented in LED

drivers. However, for RGB LEDs, if using a single register to achieve both color mixing and intensity control,

color distortion can be observed easily when using a logarithmic scale. The LP50xx device, with independent

color-mixing and intensity-control registers, implements the logarithmic scale dimming control inside the intensity

control function, which solves the color distortion issue effectively. See Figure 7-2. Also, the LP50xx device

allows users to configure the dimming scale either logarithmically or linearly through the global Log_Scale_EN

approach. See Figure 7-3.

8 Bits Brightness

Brightness Control

Linear OR Logarithmic

Log_Scale_EN

Figure 7-2. Logarithmic- or Linear-Scale Intensity Control

100 %

80 %

60 %

40 %

20 %

0 %

128

160

192

224

255

LEDx_BRIGHTNESS Register Input

Logarithmic Scale Dimming Curve

255

100 %

80 %

60 %

40 %

20 %

0 %

128

160

192

224

LEDx_BRIGHTNESS Register Input

Linear Scale Dimming Curve

Figure 7-3. Logarithmic vs Linear Dimming Curve

7.3.1.3 12-Bit, 29-kHz PWM Generator Per Channel

7.3.1.3.1 PWM Generator

With the inputs of the color mixing and the intensity control, the final output PWM duty cycle is defined as the

product obtained by multiplying the color-mixing register value by the related intensity-control register value.

The final output PWM duty cycle has 12 bits of control accuracy, which is achieved by a 9 bits of pure PWM

LP5018, LP5024

SLVSEB8C – OCTOBER 2018 – REVISED JULY 2024

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