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LM3466

W H Sieg
Prodigy 10 points
Other Parts Discussed in Thread: LM3466, LM3464

10x  LM3466 will be placed onto 10x individual discrete PCBs with each PCB  running one string of LEDs. The individual discrete LED strings and PCBs will be placed 6-8ft apart (total distance from driver 80ft.. They will be connected by a plug-in mufti-conductor cable. CAN THIS BE DONE?

Can current control be added to the input to each string to be able to use a CV power supply instead of CC?

Options for Dimming?

Occupancy sensor?

Daylight sensor?

  • 0
    Prodigy 90 points

    Hi W H Sieg

    Did this ever get done?  How did it work out?  I would like to know if LM3466 worked from discrete led boards.

  • 0
    TI__Mastermind 28655 points
    Hello,

    I would not recommend using the LM3466 across ten boards as a current sharing device. They are trying to share current from a single current source to multiple LED strings. If you want to try this I would place all LM3466s on the same board and run wires to the LEDs. I would also make sure there is a capacitor from Iled to ground as the datasheet states for long wire LED connections. The LM3466 is designed to share current among multiple channels. They need to be on the same board so the ground of the IC is common (the reference for current sharing).

    It may be possible to turn the LM3466 into independent current regulators but this has not been tried.

    If you want to use a CV power supply the LM3464 is better suited for that.

    As for dimming and sensors, if this is to be controlled overall that would have to be done at the power source. If independently that is a different design, perhaps with the LM3466 setup to regulate current.

    Thanks,
  • 0 in reply to Irwin Nederbragt
    Prodigy 90 points

    Thank you for the response.  Based on your comments I would place the LM3466 on the same board so they share a common ground point.  

    Four amp constant current supply feeding 4 strings of 12 white LEDs.   How well do you think the LM3466 will perform at 1amp string current?

    Considering the TO-220 package.  

  • 0 in reply to Stuart Linzer
    TI__Mastermind 28655 points
    Hello,

    It depends on your LEDs and voltage drops on the wires. If the LED stacks are very close to the same Vf and the voltage drops on the wires are low the LM3466s should dissipate close to the same amount of power. For every volt difference there will be one watt of extra dissipation in the lower overall stack/wire at one amp operation. The TO-220 part would be easier to heatsink. The other part would work fine on metal clad board or a good thermal designed FR-4 with thermal vias and a lot of copper plane at higher copper thickness (see page 11 of the datasheet).

    It should work fine at one amp provided the thermal design is solid and the variance of the strings isn't too high.