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LP8863-Q1: Can LP8863-Q1 be used without the boost converted function?

Part Number: LP8863-Q1

Hello guys,

One of my customers are looking for a 6ch LED driver which can drive 2 series LED (Vf=3.0V, Total Vf = about 6V) with 100mA at 1ch.
Also they need each channel separate analog dimming capability through I2C I/F.

They have the following question. Could you please give me your reply for them?

Q.  We can provide 7V~9V power supply for LED anode side. So we don't need boost converter function of LP8863-Q1.

      Can LP8863-Q1 be used without the boost converter function? Does the device work correctly when 7V~9V power supply is connected to LED anode side directly?

Your reply would be much appreciated.

Best regards,

Kazuya.

  • Hello Kazuya-san,

      Our experts for this device are currently celebrating Chinese New Year.  Someone will respond to you next week.

    Regards,

    ~Leonard 

  • Hello Leonard,

    Thank you very much for your reply.
    I understood. I'm looking forward to receiving reply from expert of your team.

    Thank you again and best regards,

    Kazuya. 

  • Hello, Kazuya, 

    It's not recommended. there will be 1.8W power loss on 6 channel and thermal protection might be triggered. 

    Regards 

    XG

  • Hello XG,

    Thank you very much for your reply.

    If the LED anode voltage is kept to 7V precisely, I think the power consumption at sink current drivers
    would be reduced to 0.6W. 

    In this condition, is it no problem to use LP8863-Q1 without all external parts of boost converter portion (Current sense resistors, FETs, Inductor, Diode)?

    Could you give me your reply?

    Thank you again and best regards,

    Kazuya. 

  • Hi, Kazuya,

    No problem. 

    Regards, 

    XG. 

  • Hi XG.

    Thank you very much for your reply.

    Could you please give me your reply about the following questions?

    Q1. Are the following connections of LP8863-Q1 boost converter portion un-used terminals correct?

           VSENSE_P   : Vin
           VSENSE_N   : Vin
           SD                 : OPEN
           GD                : OPEN
           ISNS             : GND
           FB                 : 1.3V approx
           DISCHARGE: OPEN      
           CPUMP         : OPEN
           C1P               : OPEN
           C1N               : OPEN

    Q2. Is there any register should be set "1" or "0" to disable the LP8863-Q1 boost converter?

    Thank you again and best regards,

    Kazuya.

  • Hi, Kazuya, 

    Frankly, LP8863 will be overdesigned for this kind of application. Maybe you can consider linear LED drivers like TPS926XX family. 

    Regards, 

    X.G

  • Hi Xiaoguang,

    Thank you very much for your recommendation.

    The customer requirements for LED driver are the follows.
     1. 6 channel 100mA constant current driving for 2 LED in series.
     2. Analog dimming capability to avoid flickering because the LED driver is used for video camera light source.

    I think that TPS926XX family doesn't have analog dimming capability through I/F though it is constant current driving.

    LP8863-Q1 has the analog dimming capability.

    Could you please recommend me any LED driver which has analog dimming capability through I2C?

    Also could you please tell me whether LP8863-Q1 terminals setting is no problem or not?

    Thank you again and best regards,

    Kazuya. 

      

  • Kazuya, 

    I think the configuration is ok. There is no register to disable boost converter as I know. 

    I will loop you in separate email with other guy to see if lower cost solution available. 

     

    Regards, 

    XG. 

  • Hi Xiaoguang,

    Thank you very much for your reply.
    Your reply is very helpful for the customer and me.
    They decided to evaluate LP8863-Q1 and requested us to prepare this device samples because of your support.

    Thank you again and best regards,

    Kazuya.