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LP8860 / Brightness fluctuation

Kuramochi Tadahiko
Guru 28715 points


Hi,

My customer is evaluating the LP8860EVM.

Then, brightness fluctuation was observed on following condition.

Vin=7V, LED=8S4P, DISP_CL1_BRT=oxFF, DISP_CL1_CURRENT=0x01, 

We observed it in the dark room.

The waveform is following.

Is there any setting to reduce this fluctuation?

Best Regards,

Kuramochi

  • 0
    TI__Expert 4565 points

    Hi Kuromachi-san,

    This seems happen by inaccurate switching of LED driver FET. I guess your LED driver FET setting is only using big size FET.

    If this inaccuracy at low current condition matters, you can choose smaller FET option to get more accurate current value at low current settings.

    EEPROM addr 0x66[2] is the option you can try.

    Please let me know if this doesn't improve the symptom. Actually, we haven't got any inputs for this low current condition, so don't have much info yet. Is customer controlling brightness by changing LED current fixing brightness input to 100%?

    Hope this helps,