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LP8860 Cluster Mode - Independent string control

Sheldon Sun
Prodigy 20 points
Other Parts Discussed in Thread: LP8860-Q1

Hello,

Is it possible to control 4 strings individually with all strings connected to the Vboost?

Thanks,

Sheldon

  • 0
    TI__Prodigy 460 points

    Hi Sheldon,


    are you talking about case when all strings are in cluster mode?

    Basic answer - yes. If current is different (I hope number of LED is same in every string), boost can be used in not adaptive mode, just to be sure voltage is enough and it is not too big to overheat chip or trigger LED shorted fault.

    When part of strings are in display mode, adaptive voltage can be used - but you have to be sure this voltage is ok for cluster mode strings which are not included in adaptation loop.

    EEPROM settings for fault should be chosen properly.

     

    Best regards,

    Vladimir

  • 0 in reply to V.Trondin
    Prodigy 20 points

    Thanks for the response.  So I have the evaluation board for the LP8860.  I have the following setup.

    1. 4 strings equal LED in each string

    2. Each string connected to Vboost

    3. Configure EEPROM in cluster mode (setting provided in evaluation kit)

    I notice that cluster 1 controls the brightness for all the LED strings, how do I configure the device to independently control each string of LEDs.

    Regards,

    Sheldon

  • 0 in reply to Sheldon Sun
    TI__Prodigy 460 points

    Hi Sheldon,

    looks like your LP8860-Q1 is not configured correctly, probably before loading EEPROM file, EEPROM is not unlocked or EEPROM is not burned.

    When configuration is correct, cluster 1 controls only 1st string. Can you please disable/enable chip again and read EEPROM (Operation->Read EEPROM). Check LED driver tab, PWM mode. Should be:

    Best regards,

    Vladimir