Author Topic: 5v voltage regulator gets hot with 9v  (Read 6151 times)

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Offline garriwilsonTopic starter

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5v voltage regulator gets hot with 9v
« on: July 23, 2007, 08:41:25 PM »
When I plug in my 9v to the snap connection my 5v regulator gets really hot. Is that a problem or is that supposed to happen?

Offline hgordon

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Re: 5v voltage regulator gets hot with 9v
« Reply #1 on: July 23, 2007, 08:57:46 PM »
If it's hot enough to generate smoke, you probably have a short circuit on the +5V side of your circuit.
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Offline garriwilsonTopic starter

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Re: 5v voltage regulator gets hot with 9v
« Reply #2 on: July 23, 2007, 09:00:15 PM »
After posting this I plugged it in again and it's cool no heat at all.  ???Oh well at least it works again lol 8)

Offline ed1380

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Re: 5v voltage regulator gets hot with 9v
« Reply #3 on: July 24, 2007, 07:09:57 AM »
thats normal cause it's converting 4v into heat
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Offline Brandon121233

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Re: 5v voltage regulator gets hot with 9v
« Reply #4 on: July 24, 2007, 08:20:19 AM »
You should look into using a linear voltage regulator like the MAX638. It is a whole lot more efficient.
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Offline garriwilsonTopic starter

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Re: 5v voltage regulator gets hot with 9v
« Reply #5 on: July 24, 2007, 10:59:17 AM »
Too late I already bought everything on the list. Maybe for next robot.

Offline ed1380

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Re: 5v voltage regulator gets hot with 9v
« Reply #6 on: July 25, 2007, 06:14:28 AM »
Too late I already bought everything on the list. Maybe for next robot.
you can get one from free as a sample.
not that exact one maybe, but a similar one
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Offline garriwilsonTopic starter

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Re: 5v voltage regulator gets hot with 9v
« Reply #7 on: July 25, 2007, 10:29:18 AM »
where?

Offline frank26080115

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Re: 5v voltage regulator gets hot with 9v
« Reply #8 on: July 25, 2007, 10:52:24 AM »
ST has some great stuff you can sample, I just got a few LDO regulators from them, theirrrrrrrrrrrrr great!

hope this link works
here

Offline garriwilsonTopic starter

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Re: 5v voltage regulator gets hot with 9v
« Reply #9 on: July 25, 2007, 12:36:19 PM »
is it free shipping?

Offline Robotboy86

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Re: 5v voltage regulator gets hot with 9v
« Reply #10 on: July 25, 2007, 02:57:34 PM »
It might just be me BUT

If you REALLY need to convert 9v to 5v.. perhaps put a 7v regulator in between it.  That way one is converting say 2w's out, and so it the other one..


I assume its like a 1a current..    thats the great thing about circuits..  you can run a lot of things in series or parellel and spread the job around

Offline ed1380

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Re: 5v voltage regulator gets hot with 9v
« Reply #11 on: July 25, 2007, 03:19:25 PM »
but most mcu's can't handle over 5.5v
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Offline Robotboy86

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Re: 5v voltage regulator gets hot with 9v
« Reply #12 on: July 25, 2007, 05:26:08 PM »
If they can't handle over 5.5v's then convert it to BELOW 5.5v's??

Offline ed1380

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Re: 5v voltage regulator gets hot with 9v
« Reply #13 on: July 26, 2007, 12:50:04 AM »
If they can't handle over 5.5v's then convert it to BELOW 5.5v's??

lets say you're strong enough to carry 55lb
if we gave you 56 you'd collapse.
so we give you 55 or less


I'm not good at examples
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Offline Robotboy86

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Re: 5v voltage regulator gets hot with 9v
« Reply #14 on: July 26, 2007, 05:12:52 PM »
...

so convert it to below 5.5v's?

lol.  If it fry's at 5.6v's, and needs 4v's to work, give it 5 volts

Offline ed1380

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Re: 5v voltage regulator gets hot with 9v
« Reply #15 on: July 26, 2007, 08:34:44 PM »
actually in teh datasheet it'll tell how much it needs.

IIRC the atmega8 needs 4.5-5.5v
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Offline elixier

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Re: 5v voltage regulator gets hot with 9v
« Reply #16 on: July 27, 2007, 10:31:57 AM »
Ya its a common cause that a +5v regulated power supply gets heated up
always go for a Heat Sink to dissipate extra heat from the regulator.

one problem also comes when the reulator gets extra heated up and gets automatic cutoff. this is mainly due to the fact that most of the regulators have an heat sensors inbuilt in it.
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Offline elixier

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Re: 5v voltage regulator gets hot with 9v
« Reply #17 on: July 27, 2007, 10:58:10 AM »
Again providing Heat Sink you can get the Linar voltage supply inspite of extra heating .

If you are developing the Regulated Power supply for Logic Input then why not make a variable voltage power supply and make it configurable so as to use it in any circuit as i m doing in my case.

I will give you the image of the circuit for the Voltage Regulator using IC LM317T

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