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LM3466: LM3466

Raf
Prodigy 40 points
Part Number: LM3466

I am designing a controller card using LM3466 (or any other suitable IC) to balance the current for 15 arrays of 44 LED in each array. The Forward voltage is 3.1V to 3.4V. So in total 3.4 x44= 149.6V (maximum). We are using Constant current source power supply (limited to 2.1A). From the datasheet, it is recommended to use External MosFET circuit. (Please refer to the below image). But I could not able to find any suitable part number for the MosFet and resistor values. Can you please guide me with some recommended part number/resistor values based on my requirement. Thanks.

  • 0
    TI__Genius 13001 points

    Hi,

    For MOSFET, Vds should be larger than 225V and Id should be larger than 3A. Besides, it would be better to select lower Rds to decrease power dissipation. 

     Rled is about 1MOhm. For Rdc1, it depends on the Zener diode characteristics, Rdc1=(Vled-12V) / Ileakage.

    BR,

    Robin

  • 0 in reply to Yuting Shao
    Prodigy 40 points

    Yuting Shao said:

    Hi,

    For MOSFET, Vds should be larger than 225V and Id should be larger than 3A. Besides, it would be better to select lower Rds to decrease power dissipation. 

     Rled is about 1MOhm. For Rdc1, it depends on the Zener diode characteristics, Rdc1=(Vled-12V) / Ileakage.

    BR,

    Robin

    Hi Robin, Thanks for your reply.

    Each branch the current is maximum 0.14A and Vf is around 150V.

    If I connect as in the attached image will it balance the current for all the 5 channels? 

    The Power supply for the External MosFET can I share for all the 5 channels?

    Thanks & regards,

    Rafiq

  • 0 in reply to Raf
    TI__Genius 13001 points

    Hi,

    Since each string current is controlled individually, the current is balanced.

    Yes, they can share the same power supply.

    BR,

    Robin

  • 0 in reply to Yuting Shao
    Prodigy 40 points

    Hi Robin,

    Thanks for your advise. I will try to connect and try.

    The RDC1 & RDC2 what value is suitable?

    For the 12V Zener, 1/2watt is enough, am I correct?

    Thanks,

    raf