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¿Max output current: 3A? no way.

  • Stendall Saturday, April 21, 2012 7:53 AM Reply
    That's the maximun output power of the LM2596. With heatsink enough to dissipate that power.
    With this configuration I seriously doubt the LM2596 can handle currents in excess of 1A.


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  • CarlosLint Thursday, June 28, 2012 9:36 PM Reply
    The TO-263 surface mount package tab is designed to be soldered to the copper on a printed circuit board. The copper
    and the board are the heat sink for this package and the other heat producing components, such as the catch diode and inductor. The PC board copper area that the package is soldered to should be at least 0.4 in 2, and ideally should
    have 2 or more square inches of 2 oz. (0.0028) in) copper. Additional copper area improves the thermal characteristics, but with copper areas greater than approximately 6 in 2, only small improvements in heat dissipation are realized. If further thermal improvements are needed, double sided, multilayer PC board with large copper areas and/or airflow are recommended.

    The above mentioned part was extracted straight from national's lm2596 datasheet. It is valid/good to notice that the bigger the output voltage is (and the lower the in-to-out voltage ratio), the hotter the IC gets. So for 3.3v or 5v output odds are that this regulator as it is sold by DX will do just fine.
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  • nwanto Thursday, August 30, 2012 12:01 PM Reply
    use it at about 700mA with ~13V input, 9V output, to power FRS walkie-talkie from cigarette lighter socket ; the IC gets quite hot within few minutes.
    Any suggestion on how to add heatsink to the already soldered IC ?
    Tks.
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  • frollard Friday, February 1, 2013 7:25 AM Reply
    Use thermal adhesive (thermal epoxy) and glue a small heatsink to the IC itself, being careful not to short any pins if the adhesive is conductive -- you can also add a heatsink to the BACK of the board where the IC is soldered.
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  • eatatjoes10 Friday, November 15, 2013 12:47 PM Reply
    These unsinked small boards become very hot, even at 1A output (surfaces >60°C), more than 1A for sure need an additional heatsink...
    Like CarlosLint wrote, datasheet, see page 25:
    http://www.ti.com.cn/general/cn/docs/lit/getliterature.tsp?genericPartNumber=lm2596&fileType=pdf

    Right now I run a small performance test with sku.126106:
    input 12,4V / 0,85A
    output 5V / 1,7A
    additional heatsinks: three from sku.35816 , one on the back of the LM2596S, one on the back of the inductor, one on top of it, environment 18°C, no air movement, but free airflow.
    Max. surface temperature is 65°C (the the LM2596S), and the heatsinks are too hot to touch, but it runs stable for >2 hours now.
    Before, I tried it without the heatsinks at 5V / 0,7A, temperatures where up to 70°C!

    Keep in mind, that the circuit, when switched on, will take ~1,8A (for the above conditions, only for a fragment of a second). My lab power supply shuts down, when limited below 1,7A, even with this load of 0,85A. If you put a fuse in front of the circuit, it should be a slow type, otherwise it will burn.
    experienced toddler
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