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LP8860-Q1: Channel enable/disable functions

Josef Warta
Expert 3900 points
Part Number: LP8860-Q1
Other Parts Discussed in Thread: LP8863-Q1

Hello Team, following request from customer:

I understand that display mode will set all LEDs with the same brightness and cluster mode will be able to set brightness independently for all 4 outputs. I have questions about LED control for LP8860.

 

    1. I can see brightness registers, but I can’t see any control register for enable/disable out1~out4. Is there no this kind of register?
    1. In display mode, is it able to enable/disable only one output of out1~out4? Or say all 4 outputs must be on/off the same time?
    1. In cluster mode, the adaptive mode for boost voltage output is disabled. Why is the adaptive mode disabled for cluster mode ? Any difficulty for applying adaptive mode for cluster mode?
    1. Do you have similar LED driver with similar adaptive mode and independent control strings on/off? ( we have three strings)

 

The reasons that I’m asking above questions:

 

    1. we have difficulty for our stuck_on diagnostic since we have 11 leds in series ( using out2~out4 in cluster mode), to cover worst case forward voltage, we need set boost voltage to higher side. Hence that, it’ll cause out2~4 is higher than the voltage level it’s supposed to be and make difficulty to diagnose them.
    1. we don’t care if all of them out1~out4 brightness set to the same since we only enable one string each time, we don’t mix color. If in display mode, each channel can enable/disable independently, then we can use display mode. If all selected outx must on/off at the same time, then display mode is not good for our application.
    1. We want to improve our led stuck_on, stuck_off, short and open diagnostic

 


 

Thanks

Josef

  • 0
    TI__Genius 11836 points

    Hi Josef,

    I will get back to you tomorrow.

  • 0 in reply to Charles-Chen
    TI__Genius 11836 points

    Hi Josef,

    1. In cluster mode, you can achieve independent brightness control of each channel through CLx_BRT register.

    2.on/off the same time.

    3. The LED voltage of each string can be different in cluster mode. In this mode all strings can be connected to the boost of device or an external boost can be used for indicator channels, where adaptive mode is not appropriate when external boost is used. It will be complicated to cover all the situation.

    4. LP8863-Q1.