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LM3447: Require the LED driver for Double horn Flood light and also suggestion of how to generate 5V/3Amp along with same LED driver

Abhi Choksi
Prodigy 20 points
Part Number: LM3447
Other Parts Discussed in Thread: TPS922051

Tool/software:

We have a project requirement of Double horn flood light camera with PIR sensor. Image of project is attached.
In this project we have two horns containing array of white LEDs. We need solution for this LED driver also it should include support of dimming from some microcontroller PWM pin. We have checked power integrity portfolio and found reference design "DER-657 - 45 W High Power Factor, Isolated Fly back with Switched Valley Fill PFC LED Driver" but this design doesn't include any dimming support. Requirement for LED driver is 120Vac/240Vac 50/60Hz input and output is 80V/580mA dimmable .

Can we have suggestion on above requirement?

Along with above design can we use single fly-back transformer to generate dimmable supply for LEDs and 5V/3Amp supply for MCU section? If that's possible then please suggest the reference design and part as well.

  • 0
    TI__Mastermind 23190 points

    Hi Abhi,

    If you only want a single flyback transformer with separate secondary windings for MCU power and LED power, then I would recommend you first use a normal constant-voltage flyback controller with two secondary windings - 

    • First winding - regulate the AC input to 5VDC output (used as the feedback point)
    • Second winding - (loosely) regulate the AC input to a middle voltage like 100V (It may vary to some extent due to cross regulation)

    and then use a secondary stage of constant-current LED driver to regulate this middle voltage to drive the LEDs.

    If it is possible, I would recommend you change the configuration (parallel / series) of the LED array so that its voltage is lower, like 40V @ 1.16A. With this configuration, you can find more LED drivers with suitable voltage ratings, like TPS922051 (At this time, for example, you can set the middle voltage at 55V).

    Best Regards,

    Steven