LP5526

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SNVS431C – FEBRUARY 2006 – REVISED JULY 2009

EXTERNAL PWM CONTROL

The GPIO[0]/PWM pin can be used to control the backlight drivers brightness or set leds on/off. External PWM

control is enabled by writing 1 to EN_MAIN_PWM and/or EN_SUB_PWM bits in register address 2BH.

GPIO[0]/PWM pin is used as external PWM input when EN_PWM_PIN is set high. PWM input is active high, i.e.

LED is activated when in high state.

FADE IN / FADE OUT

LP5526 has an automatic fade in and out for main and sub backlight. The fade function is enabled with

EN_FADE bit. The slope of the fade curve is set by the SLOPE bit. Fade control for main and sub display is set

by FADE_SEL bit.

Recommended fading sequence:

1. Set SLOPE

2. Set FADE_SEL

3. Set EN_FADE = 1

4. Set EN_MAIN / EN_SUB = 1

5. Set target WLED value

6. Fading will be done either within 0.65s or 1.3s based on SLOPE selection

Fading times apply to full scale change i.e. from 0 to 100% or vice versa. If the current change does not

correspond to full scale change, the time will be respectively shorter. See WLED Dimming diagrams for typical

fade times.

WLED CONTROL REGISTER (03H)

Name

Bit

Description

SLOPE

5

FADE execution time:

0 = 1.3s (full scale)

1 = 0.65s (full scale)

FADE_SEL

4

FADE selection:

0 = FADE controls MAIN

1 = FADE controls SUB

EN_FADE

3

FADE enable

0 = FADE disabled

1 = FADE enabled

DISPL

2

Display mode:

0 = MAIN and SUB individual control

1 = MAIN and SUB controlled with MAIN DAC

EN_MAIN

1

MAIN enable:

0 = disable

1 = enable

EN_SUB

0

SUB enable:

0 = disable

1 = enable

Adjustment is made with 04H (main current) and with 05H (sub current) registers:

MAIN CURRENT [7:0]

Driver current,

SUB CURRENT [7:0]

mA (typical)

0000 0000

0

0000 0001

0.1

0000 0010

0.2

0000 0011

0.3

…

…

…

…

1111 1101

25.3

1111 1110

25.4

1111 1111

25.5

Copyright © 2006–2009, Texas Instruments Incorporated

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