Author Topic: Is a CC DC-DC converter short circuit proof?  (Read 1658 times)

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Offline PeterFW

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Is a CC DC-DC converter short circuit proof?
« on: March 29, 2016, 01:58:01 am »
Hello!
So... i have a general question, i am far from a bloody beginner but i have my problems with some things.

Should a DC-DC converter with a constant current output not be short circuit proof by design?
I have this cheap chinese Minghe converter and the seller says that it is not short proof.

But... if it is current limited, should it not be by design short cicuit proof?
This perticular unit is a Buck/Boost, is that maybe the reason for it?

Greetings,
Peter
 

Offline mikeselectricstuff

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Re: Is a CC DC-DC converter short circuit proof?
« Reply #1 on: March 29, 2016, 02:15:52 am »
If it is true constant current, yes, however in practice it may not give constant current over its whole output voltage range.
e.g. a LED flyback boost driver would give CC as long as Vout>Vin, but below that, Vin would be connected to Vout vis the inductor and diode
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Offline michaeliv

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Re: Is a CC DC-DC converter short circuit proof?
« Reply #2 on: March 29, 2016, 04:44:05 am »
Most likely it is specified as non-short-circuit protected because if you for example set the output to 30v and set the CC limit to maximum, short circuiting it will destroy it. So, in this case it wouldn't be short-circuit protected.
 

Offline PeterFW

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Re: Is a CC DC-DC converter short circuit proof?
« Reply #3 on: March 29, 2016, 09:39:38 am »
Hello and thanks for your reply!

If it is true constant current, yes, however in practice it may not give constant current over its whole output voltage range.

Seems like i will have to do some (potentially destructive) testing.

I have addet INA226 to log the voltage and drawn current from the connected devices to an SD card.
Since the INA226 has a programable latching alert output i will wire a relay in series and have the output disconnect in case of over current.

That should help a bit in case things go wrong.

Edit: See the attachment of the module in question, the INA226 PCB is not my proudest work... :)

Quote
e.g. a LED flyback boost driver would give CC as long as Vout>Vin, but below that, Vin would be connected to Vout vis the inductor and diode

That makes sense, thank you!

On a side note, i love your videos, been watching them for quite some time now! Thank you!

Most likely it is specified as non-short-circuit protected because if you for example set the output to 30v and set the CC limit to maximum, short circuiting it will destroy it. So, in this case it wouldn't be short-circuit protected.

Thanks, i will wire it up and see what will happen with a suitable resistive load. It is not that cheap (20 bucks) but i guess i will have to do some destuctive testing.

Greetings,
Peter
« Last Edit: March 29, 2016, 09:50:05 am by PeterFW »
 

Offline crazy horse

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Re: Is a CC DC-DC converter short circuit proof?
« Reply #4 on: March 29, 2016, 09:48:13 am »
If it is designed right it really should be.
 

Offline station240

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Re: Is a CC DC-DC converter short circuit proof?
« Reply #5 on: March 30, 2016, 12:51:37 pm »
If it is designed right it really should be.

I have this cheap chinese Minghe converter and the seller says that it is not short proof.

Highlighted the proof it's not designed properly.
Sadly the only way to know if these cheap chinese converters are any good is to either:
1. Reverse engineer it circuit, or find someone that did.
2. Run a few basic tests, and see if it blows up under normal working conditions.
It's best to do #1, rather than both |O
 


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