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LM36923: LM36923 curve

user5084989
Prodigy 10 points
Part Number: LM36923

There are 256 backlight level (0~255) in Android, the backlight node is /sys/class/leds/lcd-backlight/brightness, But there are 2048 level in LM36923 11-bits backlight register 0x18 and 0x19.

Could you provide a recommend translate function or typical mapping table from Android 256 level to LM36923 2048 level which depends on LM36923 brightness regiser and LED current exponential mapping?

  • 0
    TI__Intellectual 2140 points
    Hi,

    Please allow a little time for someone to work on a mapping algorithm. We'll get back to you shortly.

    Regards,
    Angelos Tsiros
  • 0 in reply to Angelos Tsiros
    TI__Intellectual 2090 points
    Hi,
    In the case of mapping 256 levels to 11-bit brightness it is recommended to keep brightness lsb register setting (0x18=0x07) and then map the 256 brightness levels to brightness msb (0x19). It is necessary to also enable ramp (bit 4 in register 0x11), the LM36923 will use 11-bit control to transition between 8-bit brightness levels. The mapping equation is 50uA x 1.003040572^(Code x 8). The range is from 51.22uA to 25mA with a step size of 2.43%.
    Let me know if you need additional information.
    best regards,
    Randy