LP8556 datasheet(16/63 Pages) TI1

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LP8556

SNVS871I – JULY 2012 – REVISED MARCH 2016

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8.3.2.3 BRT_MODE = 10

With BRT_MODE = 10, the PWM output is controlled only by the Brightness register. From BRT[7:0] register, the

data goes through the PWM Curve Shaper block. Then, the data goes into the Adaptive Dimming function which

determines the range of the PWM and Current control as described in Output Dimming Schemes. The outcome

of the Adaptive Dimming function is 12-bit Current and / or up to 6 PWM output signals. The current is then

passed through the non-linear compensation block while the output PWM signals are channeled through the

Dither block.

8.3.2.4 BRT_MODE = 11

With BRT_MODE = 11, the PWM control signal path is similar to the path when BRT_MODE = 01 except that the

PWM input signal is multiplied with BRT[7:0] data after the Curve-Shaper block.

Table 2. Brightness Control Methods Truth Table

PWM_DIRECT

BRT_MODE [1:0]

BRIGHTNESS CONTROL SOURCE

OUTPUT ILED FORM

External PWM signal

Adaptive. See Output

Dimming Schemes

External PWM signal and Brightness Register

(multiplied before Curve Shaper)

Brightness Register

External PWM signal and Brightness Register

(multiplied after Curve Shaper)

don't care

External PWM signal

Same as the external

PWM input

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