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LM3404HV maximum Output power

sumathi Sapthagiri
Intellectual 390 points
Other Parts Discussed in Thread: LM3404HV, TPS40210, LM3429, LM3404, LM3424, LM3409

Hi,

We are designing a power adapter module for lighting control system. We are using LM3404HV. The requirement is to drive LED Strips ( 36 numbers , 1W each LED) , voltage required is 52V to 62V @ 36W.  Previously the LED strip was driven by the AC to DC Ballast. The power adapter module is designed to replace AC to DC Ballast. The Ballast DC output is 52V to 62V @ 36W. with Load.. With no Load the voltage can go upto 69V. 

The query is Whether the LM3404HV be used to drive LED's with 36W Power, DC voltage of 52 to 62V and current 700mA to 1A max?

Currently the Input to the Power adapter module is from POE PSE switch which can supply IEEE802.3 af and at specification. Power upto 60W. A POE PD module is used on Board to convert the voltage from 48V to 24V.

The PD module output of 24V is Boosted to 64V using TI TPS40210 Boost regulator. The output of TPS40210 is used to input of LM3404HV. here boost and LED driverer is used in two chip solution for thermal consideration. TPS40210 does not support Thermal protection shutdown. Where as the LM3404HV has the Thermal shutdown feature.

Kindly let me know the maximum output power supported by LM3404HV.

Regards,

Sumathi

  • 0
    TI__Mastermind 25500 points

    Hello Sumathi,

    The limitation is mainly thermal. So calculating the I^2*Rds(on)*D should be easy enough, but at such a high input voltage the AC losses become significant as they are directly proportional to Vin^2 and Fsw. So the answer is that yes, it should be able to do it, but it may require a low switching frequency and high inductor value to keep the AC losses low enough to avoid thermal shutdown.

    Thanks,

    Clint

  • 0 in reply to Clinton Jensen
    Intellectual 390 points
    Hello Clinton,
    Thanks for the reply and support.
    Kindly advice the good option
    1) Single chip Boost + LED driver like LM3429
    2) Two chip solution, like Boosting the voltage to high 64V (TPS40210) + Buck LED Driver (LM3404HV)
    Once the POC(proof of concept) is ready , it will be produced in large quantities. Kindly help which option is good.
    Please reply ASAP.

    Regards,
    Sumathi
  • 0 in reply to sumathi Sapthagiri
    TI__Mastermind 25500 points

    Hello Sumathi,

    It really depends on your requirements. Do you need PWM dimming? If so how fast does it need to be?

    The easiest way would be to just use a boost such as the LM3429 from the 24V rail. The LM3429 is a controller so you can size the FET to take care of the heat. It also has thermal shutdown. It can PWM dim but is generally limited to a few hundred Hz, perhaps up to 1kHz. You could also use the LM3424 if you need to have faster PWM dimming, up to 10kHz or so. If you need PWM dimming faster than that you should consider the two stage solution. If you would like improved ability to take care of thermals you could consider the LM3409 buck controller as the second stage. But the LM3404 could do it as long as you can consider using a switching frequency below about 300kHz.

    Thanks,

    Clint

  • 0 in reply to Clinton Jensen
    Intellectual 390 points

    Hello Clint,

    Thank You very much for the reply.

    Regards,

    Sumathi