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How to Boost LM317 Output Curent

Hesambook

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LM317 is one of the most popular adjustable regulator chips. The output voltage of the regulator can be adjusted from 1.25V to 35V. However, the chip can deliver currents up to 1.5A which is not enough for some power applications. In this article/video, I will discuss two methods of LM317 current boosting, using power PNP and NPN pass transistors.


References

Article: http://bit.ly/33aZQfq

[1]: LM317 Datasheet: http://www.ti.com/lit/ds/slvs044x/slvs044x.pdf

[2]: LM317 Library: https://componentsearchengine.com/part.php?partID=299235

[3]: MJ2955 Datashet: https://www.mouser.com/datasheet/2/308/2n3055-d-1190033.pdf

[4]: MJ2955 Library: https://componentsearchengine.com/part.php?partID=697997

[5]: 2N3055 Datahseet: https://www.onsemi.com/pub/Collateral/2N3055-D.PDF

[6]: 2N3055 Library: https://componentsearchengine.com/part.php?partID=788620

[7]: CAD Plugins: https://www.samacsys.com/library-loader-help
 

rufus_b

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You could have shown much better voltage regulation under load if You would have used real wires and not this flimsy breadboard connectors and wires. Even if these are only a few centimeters long, at 3 amps You have a relevant resistance through this wires and the breadboard contacts.

I just took the time and soldered the few parts with thicker wire (something like AWG16). Using a 2.2Ω load at 7Volt the output voltage dropped only 2 millivolt.

Rufus
 

Hesambook

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You could have shown much better voltage regulation under load if You would have used real wires and not this flimsy breadboard connectors and wires. Even if these are only a few centimeters long, at 3 amps You have a relevant resistance through this wires and the breadboard contacts.

I just took the time and soldered the few parts with thicker wire (something like AWG16). Using a 2.2Ω load at 7Volt the output voltage dropped only 2 millivolt.

Rufus
Yes, that's why I suggested at the end to build this on a PCB and you would get better results
 

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