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LM3550: Do this IC fet my needs?

Paulo Carmo
Prodigy 30 points
Part Number: LM3550

Good afternoon,

My name is Paulo Carmo, I´m a electronic developer in MCM.

My next task is develop a electronic board to driver LEDs for medical applications. The driver must provide constant corrent to several LEDs that will be in serial. This corrent should be regulated between 250mA and 3A. The LEDs should be switched on during the exposure time of camera (between 0,5 and 3 ms), I have a pulse with this information, the maximum frequency will be 30Hz. The maximum time between my switch on and the corrent pass by LEDs should be 5us. Now I´m trying to chose the IC, do you think LM3550 can fet my needs? Do you think is my best option?

Thanks, Paulo Carmo

  • 0
    TI__Intellectual 1940 points

    Hello,

    The LM3550 uses a supercapacitor and an external FET to control the current.  The max output voltage this device is able to support is about 5V, so putting multiple LEDs in series would not work in this case unless you are drive a couple of RED or IR LEDs that have a lower forward voltage.

    To better understand the application, I have a few questions.

    • How many series LEDs are planned?
    • Do you need to have a boost converter built into the device to deliver the power to the LED?  
    • What is the supply voltage used to drive this application?  

    Thanks.

    Greg

  • 0 in reply to Greg Lubarsky
    Prodigy 30 points

    Hi,

    I will use up to 384 Marubeni SMT750, that has a pulse current of 500mA and I will use ut to 48 CREE XPLAWT-00-0000-000LV40E5 that I want drive with 3A ( I think can be less). Of course, I can use several constant current circuits.

    As far as I understood I can not use this IC, because the super caps needs 5 or 6 seconds to charge.

    Do you know other options?

    Thanks