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LM3466: cnguyen00@irtronix.com

Chien Nguyen90
Prodigy 30 points
Part Number: LM3466
Other Parts Discussed in Thread: LM3464

I am using LM3466  to drive 3 strings of LED (350mA each) as per Figure 19 in the data sheet.

Do I have to use a constant current source to drive these application?

I used a bench top DC power supply with current limit setting and found that the LED current is not regulated but continue to climb until reaching the current limit setting of the bench top power supply which is not what I would like to have.

I know the data sheet stated that LM3466 is to use with constant current source but don't understand why.

Does the circuit work properly if I use a constant current source with higher current capability and rely on the LM3466 to regulate the current to desired setting of 350mA for each string?

Best regards,

Chien Nguyen

  • 0
    TI__Mastermind 28655 points

    Hello Chien,

    The LM3466 is not a current regulator, it shares current with other LM3466s.  They need to be driven with a current source, the idea is to source 1.05 amps in your case to be shared among three LM3466s at 350 mA each, 3X 350 mA = 1.05A.

    Again, the LM3466 does not regulate current so if you use one and give it 350 mA it will put 350 mA to the LEDs, if you increase the current the LED current will increase as well.  If you use two LM3466s it will divide the current source in half for each string, if you use three it will divide it by three sending 1/3 of the current to each LED string (which is what you are trying to do).

    The LM3464 is a multi channel current regulator that can limit how much current goes to each led string.  To be efficient it needs to control the voltage headroom via the dynamic headroom control.

    Regards,