Author Topic: LM317 SOURCE  (Read 2941 times)

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Offline nico2984Topic starter

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LM317 SOURCE
« on: August 17, 2015, 09:25:15 pm »
Hi, I need to build a 0 to 5V regulator (1A max) with a overcurrent protection (foldback)
I usually implement a protection when I have an additional output series transistor to increase the current rating of the power supply (external pass element), but in this circuit I don't need it.
How can I implement the protection?
 

Offline tron9000

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Re: LM317 SOURCE
« Reply #1 on: August 17, 2015, 09:28:16 pm »
have a look at daves videos on designing power supplies
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Offline rsjsouza

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Re: LM317 SOURCE
« Reply #2 on: August 17, 2015, 09:36:50 pm »
I am not sure if I understood it correctly, but the LM317 has built-in current limiting circuitry. Do you mean something else?
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Offline nico2984Topic starter

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Re: LM317 SOURCE
« Reply #3 on: August 17, 2015, 09:40:47 pm »
I am not sure if I understood it correctly, but the LM317 has built-in current limiting circuitry. Do you mean something else?

Yes, I have to implement another overcurrent protection additionally to the LM317 built-in
 

Offline ez24

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Re: LM317 SOURCE
« Reply #4 on: August 17, 2015, 09:53:18 pm »
I see PolySwitch Resettable Fuse mentioned a lot

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Offline nico2984Topic starter

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Re: LM317 SOURCE
« Reply #5 on: August 17, 2015, 10:10:22 pm »
Thanks ez24, but I forgot to mention that this is an exercise from school.
I updated my design.
I have to design a voltage regulator (1A, 0 to 5v). The input can variate between 40 to 45v. Also I have to implement and overcurrent protection (foldback current protection).
 

Offline nico2984Topic starter

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Re: LM317 SOURCE
« Reply #6 on: August 17, 2015, 11:39:03 pm »
Yes, the standard 317 only rated to 40v, that's why I put the Q1. It's reduce the Vin to 30v.

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Offline ez24

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Re: LM317 SOURCE
« Reply #7 on: August 18, 2015, 02:38:16 am »
To OP

If you want more responses, change the title of your post.  Your title means nothing, you need to ask for ideas in your title and use up all the space (it is free).

Something like:  "Suggestions for current feedback in a LM317 circuit needed"

Does you circuit have a -10v input ?
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