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Will this switching down-regulator protect at all against short-circuits?

Peter Freund

Jun 10, 2015
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Can anyone tell me if this switching regulator with input of 15.4v and output of 12v (for my purposes) will offer any kind of short-circuit protection if the output leads cross/short? I don't care if it fries the regulator, I just want to know what will happen if there's a short.

https://www.dimensionengineering.com/products/de-swadj

Thank you!
 

(*steve*)

¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd
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From the datasheet, currents in excess of 1.5A may permanently damage the device.

One possibility is that the switching device (probably a mosfet) will fail short circuit and you will have the full 15.4V output until something else fails.
 

hevans1944

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Jun 21, 2012
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There is this note from the device datasheet:

Overcurrent/overtemperature behavior
If the current limit has been considerably exceeded or if the device is overheated the product will gradually reduce the output voltage in an attempt to reduce the load on the device. Once the extra load is removed or the temperature is brought down, the desired output voltage will be restored. It is unlikely that you will destroy the regulator by exceeding the current/temperature ratings but we still recommend practicing good engineering techniques and do not overload the device beyond the recommended operating parameters
.

So, my guess is... don't short-circuit the output.
 

Peter Freund

Jun 10, 2015
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I guess I am more concerned with the power source. I'm an electronics amateur. This regulator is being used on a quadcopter to downcovert current of battery (Lipo 4S at 15.4v) to 12 volts. I just want to know if the LED light being fed 12v current from the regulator shorts out somehow, will it cause the whole quadcopter to blow up? Overheat? Turn off? Malfunction?
 

hevans1944

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I guess I am more concerned with the power source. I'm an electronics amateur. This regulator is being used on a quadcopter to downcovert current of battery (Lipo 4S at 15.4v) to 12 volts. I just want to know if the LED light being fed 12v current from the regulator shorts out somehow, will it cause the whole quadcopter to blow up? Overheat? Turn off? Malfunction?

None of these things will happen IF the LED has an appropriately sized resistor in series with it to limit the current.
 

cjdelphi

Oct 26, 2011
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You could add a current limiter to prevent a short like an opamp and a shunt resistor or just use the appropriate resistor ..
 

cjdelphi

Oct 26, 2011
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A polyfuse might be another option say 500ma which will stop a dead short...
 

Peter Freund

Jun 10, 2015
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All these answers PRESUPPOSE that my regulator will NOT provide fuse protection. I still want to know whether this regulator will offer short circuit protection ON ITS OWN. Thanks.
 

cjdelphi

Oct 26, 2011
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No.... the point of the regulator is to supply max current (when shorted) the only protection will be when it's thermal protection kicks in reducing the current.
 

Peter Freund

Jun 10, 2015
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No.... the point of the regulator is to supply max current (when shorted) the only protection will be when it's thermal protection kicks in reducing the current.

I'm not following you. It sounds like you said NO and then YES: no it won't but it will "when shorted" and by "reducing the current". I'm confused. Here's an illustration:

(BATTERY) ---(connected to)---> Switching Regulator ----(connected to)---> GPS tracker

If the leads GOING TO the GPS tracker short or touch each other, what will happen to the BATTERY?
 

cjdelphi

Oct 26, 2011
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If the leads going to the tracker cross, the lm2596 will supply as much current as possible until the chip warms up to the point it will burn you if touched, at which point a few seconds it will begin reducing current ..

Either the wires begin melting or the battery gets drained...
 

cjdelphi

Oct 26, 2011
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At the time the webpage you linked was dead for me...

The lm2596 is a cheap common switching regulator, probably inside the device you linked to...

The battery is?
 

hevans1944

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Quadcopters don't need a battery to blow up. They crash easily enough from other causes, but a fast-blow fuse in the battery supply wires is a good idea.
 

cjdelphi

Oct 26, 2011
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Fuse should be rated 30 - 50% higher than the max current the quad copter pulls or the fuse might blow from just using it.....
 

Peter Freund

Jun 10, 2015
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But the fuse is not going to be in-line to the quadcopter's motors. I am running wires off from the battery separately to power a GPS tracker and LED light. Together they draw maybe 50ma.
 
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