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LM3409HV: 10A LED Pulse Current

Danny Andreev
Intellectual 310 points
Part Number: LM3409HV
Other Parts Discussed in Thread: TPS92640, TPS92641

Hello,

I am designing a high current LED driver. It needs to supply 10amp pulses of at least 100us in duration and at a minimum of 240hz. Furthermore, I would like to be able to adjust the current +0/-20%

I am using Cree CXB3590 LEDs with a forward voltage of 36v (however at 10A the voltage across the led is 44V - this was found experimentally)

The system has an adjustable input power supply which outputs ~60V and I plan to have my circuit step this down to the appropriate voltage fore the LEDS.

I plan on using the lm3409HV however from other users on the forum I noticed that it is said that is limited to 5A. Since it measures current using a resistor what would stop me from lowering the current sense resistor's resistance and driving the output current higher?

Best,

-Danny

P.S. if you know of any other chips that may work better for me let me know.

  • 0
    TI__Intellectual 2590 points

    Danny,

    10A is quite high for an asynchronous buck converter.  Nothing specifically would prevent you from using the LM3409HV, however the gate driver will likely not be strong enough for the PFET you need for a 10A solution.  Therefore your switching losses will be worse.  Also, the overall efficiency will be worse due to the 10A current through the recirculating diode.  Now, considering you are pulsing at very low duty cycle, this may be ok. 

    Another option would be the TPS92640/TPS92641 synchronous buck LED controllers.

    I think you can do either design, but you may need a better gate driver in either case. 

    -JP